Effect of Lactic Acid Fermentation on Color, Phenolic Compounds and Antioxidant Activity in African Nightshade

Postharvest UV-B and UV-C treatments combined with fermentation enhance the quality characteristics of Capparis spinosa L. fruit, improving total phenols, flavonoids, anthocyanins, phenolic acids, and antioxidant activity

The application of UV-B and UV-C radiation may enhance the post-harvest quality of crops by delaying the ripening or aging of fruits, preventing declines in firmness, maintaining stable pH levels, increasing certain antioxidants such as phenolic compounds, and minimizing spoilage. Additionally, the fermentation process, a traditional method of food preservation, not only extends the shelf life of foods but also promotes the formation of natural bioactive components and enhances organoleptic properties. This study aimed to investigate the effects of UV radiation and fermentation on caper (Capparis spinosa L.) berries through a factorial experiment designed as a completely randomized design with three replications. Four levels of UV radiation: control (no radiation), UV-B radiation, UV-C radiation, and UV-B + C radiation were applied. Following the UV treatment, fermentation was initiated, with four sampling stages conducted throughout the fermentation period (fresh fruits or control, and days 15, 30, and 45 during fermentation). The results indicated significant increases in total phenol content, flavonoids, anthocyanins, antioxidant activity, and the activity of the enzyme phenylalanine ammonia-lyase (PAL) in caper berries treated with UV-B and, particularly, UV-C radiation. The levels of most phenolic compounds, including caffeic acid, gallic acid, p-hydroxybenzoic acid, cinnamic acid, rosmarinic acid, p-coumaric acid, m-coumaric acid, ferulic acid, protocatechuic acid, and vanillic acid, significantly increased under UV-C, UV-B, and UV-B + C exposure compared with the control (no UV application). Regardless of the UV treatment, fermentation significantly elevated the levels of phenolic acids such as caffeic acid, gallic acid, ferulic acid, m-coumaric acid, p-hydroxybenzoic acid, protocatechuic acid, rosmarinic acid, and vanillic acid, resulting in concentrations that were considerably higher in fermented fruits 45 days post-fermentation than in fresh fruits. Additionally, the total phenol and flavonoid contents in UV-treated fruits on day 45 of fermentation exceeded those in fresh fruits. In contrast, samples not exposed to UV radiation showed no significant changes in these attributes during fermentation. Overall, irrespective of the UV treatment, fermentation of the fruits up to day 30 led to increases in antioxidant activity, PAL activity, anthocyanin content, cinnamic acid, and p-coumaric acid in caper berries. However, the level of cinnamic acid decreased on day 45 compared with day 30. Ultimately, caper fruit treated with UV irradiation and fermented exhibited enhanced health potential due to their unique characteristics.

Four distinct pathways involved in a "tug-of-war" lead to the non-linear nature of phenolic chemistry during lactic acid fermentation of fruits and vegetables

Introduction Lactic acid fermentation of fruits and vegetables (F&V) is endowed with new nutrients and flavors. "Phenolics" is a hot spot in this area, which evolve irregularly during fermentation. However, the mechanism about this non-linear phenomenon has been poorly understood.Objectives This paper was aimed at decoding the mechanism about the non-linear nature of phenolic chemistry during lactic acid fermentation of F&V.Methods Mango and cress slurries were fermented by Lactiplantibacillus plantarum. Different fractions of the slurry samples were analyzed comprehensively. Four pathways relating to phenolic changes were extracted, including adsorption of free phenolics by F&V cell wall materials, microbial adsorption and biotransformation of free phenolics, destabilization of covalent bond between bound phenolics and F&V cell walls. The in-depth features of each pathway during fermentation were explored by multidisciplinary methodologies.Results Throughout both fermentation of mango and cress slurries, free phenolics and the F&V cell wall components undergo dynamic changes. Due to the reduction of pectin fraction in the F&V cell walls during fermentation, the adsorption of free phenolics by F&V cell wall materials through surface diffusion was improved. Also, microbial cells, especially in the latter stages of fermentation, were capable of adsorbing free phenolics through surface diffusion. Moreover, the padC and bglB genes encoding phenolic acid decarboxylase and β-glucosidase were expressed during fermentation, contributing to the conversion of free phenolics. Besides, bound phenolics were not released during fermentation, although its covalent was weakened. The features of the above pathways vary with the fermentation stages and the composition of F&V components, resulting in non-linear changes of free phenolics during F&V fermentation. Conclusion F&V cell wall adsorption, microbial adsorption, microbial biotransformation, and destabilization of the covalent bond of bound phenolics compete in a dynamic "tug-of-war", leading to non-linear nature of phenolic chemistry during F&V fermentation.

Microbial Ecology and Nutritional Features in Liquid Sourdough Containing Hemp Flour Fermented by Lactic Acid Bacterial Strains

Hemp seed flour (Cannabis sativa) is a non-traditional matrix alternative to wheat for baked goods production. The aim of this study was to investigate the microbiota of two liquid sourdoughs (SLs) based on hemp or a wheat-hemp mixture, before and after spontaneous or piloted fermentation (Lactiplantibacillus plantarum ITM21B or Weissella cibaria C43-11 used as starters). Culture-dependent and -independent (high-throughput sequencing of bacterial phylogenetic V3-V4 regions of the 16S rRNA gene) methods, were used to evaluate the microbial community. The effect of fermentation on the content of bioactive molecules (polyphenols, organic acids, proteins, and amino acids) was also investigated. Results indicated that the microbial community of all SLs was mainly (99.7 ÷ 100%) composed of Firmicutes and Proteobacteria, and the latter was the unique phylum before fermentation in formulations produced exclusively with hemp flour. Two PCoA plots (Test adonis with pseudo-F ratio, p > 0.05) showed no significance difference between the microbial communities of the formulations. However, the relative abundance variation at the family level in the wheat-hemp-based mixture SLs showed a significant enrichment of the Lactobacillaceae family (Kruskal-Wallis test, p = 0.04). Moreover, results confirmed hemp seed flour as a suitable fermentation substrate to obtain microbial consortia allowing for an increase in organic acids, especially lactic acid (9.12 ± 1.22 and 7.45 ± 0.75 mmol/kg with Lpb. plantarum and W. cibaria, respectively), in both piloted fermentations, and in polyphenols by 21% and amino acids by 158% in SL fermented by the C43-11 strain.

Development of a Quinoa-Based Fermentation Medium for Propagation of Lactobacillus Plantarum and Weissella Confusa in Opaque Beer Production

Product inconsistency of opaque beer has for long been a tenacious problem in the brewing industry since the current process relies on spontaneous lactic acid fermentation. In order to impede this challenge, there is a need to add lactic acid bacteria (LAB) starter cultures in opaque beer brewing to improve its organoleptic qualities. This study sought to develop a quinoa-based fermentation medium for propagation of Lactobacillus plantarum and Weissella confusa as potential starter cultures in opaque beer production. An evaluation of the stability and tolerance of the LAB under various stress conditions was also done. Fermentation wort from opaque beer brewing and different quinoa-based synthetic media with varying nutritional components was prepared for propagation of LAB. Physiochemical analyses which included pH, Brix value and total titratable acidity (TTA) of monocultured and cocultured synthetic media were measured. The measurements were done at 24 h time intervals ranging from 0 to 96 h. Tolerance studies which included the effect of heat shock, cold shock, oxidative stress and osmotic pressure on the survival rate of LAB were conducted to determine the stability of LAB. MRS with L. plantarum monoculture (MRSp) had a notable change in pH from 4.5 to 3.6 after 24 h. The cocultured (M5p + w) synthetic media and cocultured MRS (MRSp + w) also exhibited change in pH from 4.3 to 3.2 and 4.3 to 3.3, respectively, after 72 h. Brix value in all media samples decreased after 24 h except for the uninoculated MRS sample (MRS C). The synthetic and coculture medium (M5p + w) exhibited an increase in TTA (0.79% (m/v) lactic acid) within the first 24 h. Exposure to heat shock had a significance effect (p < 0.05) on the survival rate of L. plantarum and W. confusa. The W. confusa in synthetic media recorded a higher survival rate (27 ± 0.03%) upon exposure to heat shock than L. plantarum (7 ± 0.01%). In contrast, L. plantarum in MRS recorded a higher survival rate (67 ± 0.02%) upon exposure to cold shock and oxidative stress (34 ± 0.01%). The starter cultures tested survived upon exposure to the stress conditions, indicating their potential use in opaque beer production.

The Impact of Fermentation on the Antioxidant Activity of Food Products

From ancient times to the present day, fermentation has been utilized not only for food preservation but also for enhancing the nutritional and functional properties of foods. This process is influenced by numerous factors, including the type of microorganisms used, substrate composition, pH, time, and temperature, all of which can significantly alter the characteristics of the final product. Depending on the parameters, fermentation enhances the bioactive content of the products and imparts the necessary properties, such as antioxidant characteristics, for the products to be considered functional. The enhancement of these properties, particularly antioxidant activity, enriches foods with bioactive compounds and functional attributes, contributing to improved health benefits. Through a review of recent research, this study elucidates how different fermentation processes can enhance the bioavailability and efficacy of antioxidants, thereby improving the nutritional and functional qualities of foods. This study investigated the multifaceted effects of fermentation on antioxidant properties by exploring various types and conditions of fermentation. It highlights specific examples from dairy products and other food categories as well as the valorization of food waste and byproducts. The findings underscore the potential of fermentation as a sustainable method to produce health-promoting foods with elevated antioxidant activities, offering new perspectives for food science and technology.

Investigating the role of Lactiplantibacillus plantarum vs. spontaneous fermentation in improving nutritional and consumer safety of the fermented white cabbage sprouts

Brassicaceae sprouts are promising candidates for functional food because of their unique phytochemistry and high nutrient density compared to their seeds and matured vegetables. Despite being admired for their health-promoting properties, white cabbage sprouts have been least explored for their nutritional significance and behavior to lactic acid fermentation. This study aimed to investigate the role of lactic acid fermentation, i.e., inoculum vs. spontaneous, in reducing intrinsic toxicants load and improving nutrients delivering potential of the white cabbage sprouts. White cabbage sprouts with a 5-7 cm average size were processed as raw, blanched, Lactiplantibacillus plantarum-inoculated fermentation, and spontaneous fermentation. Plant material was dehydrated at 40 °C and evaluated for microbiological quality, macronutrients, minerals, and anti-nutrient contents. The results indicate L. plantarum inoculum fermentation of blanched cabbage sprouts (IF-BCS) to increase lactic acid bacteria count of the sprouts from 0.97 to 8.47 log CFU/g. Compared with the raw cabbage sprouts (RCS), inoculum fermented-raw cabbage sprouts (IF-RCS), and spontaneous fermented-raw cabbage sprouts (SF-RCS), the highest content of Ca (447 mg/100 g d.w.), Mg (204 mg/100 g d.w.), Fe (9.3 mg/100 g d.w.), Zn (5 mg/100 g d.w.), and Cu (0.5 mg/100 g d.w.) were recorded in IF-BCS. L. plantarum-led fermentation of BCS demonstrated a reduction in phytates, tannins, and oxalates contents at a rate of 42%, 66%, and 53%, respectively, while standalone lactic acid fermentation of the raw sprouts reduced the burden of anti-nutrients in a range between 32 and 56%. The results suggest L. plantarum-led lactic acid fermentation coupled with sprout blanching is the most promising way to improve the nutritional quality and safety of the white cabbage sprouts.

Impact of Lactic Acid Bacteria Fermentation Based on Biotransformation of Phenolic Compounds and Antioxidant Capacity of Mushrooms

Mushrooms contain phenolic compounds that possess health-promoting properties, including antioxidant effects. However, the low solubility and form of phenolic compounds affect their bioactivity and bioaccessibility. To overcome this limitation, our study investigates the fermentation of mushrooms to increase their free phenolic content and enhance their bioactivity. Our research focused on the impact of fermentation on both free and bound phenolic fractions (FPs and BPs, respectively) in Lentinula edodes and Lactarius deliciosus, which were successively fermented with Lactiplantibacillus plantarum LMG 17673 for 72 h. We examined the total phenolic content (TPC), phenolic profile, and antioxidant activity of both FPs and BPs. Our results showed that the TPC of BPs was higher than that of FPs in both mushrooms, with strong antioxidant capabilities. Fermentation significantly increased the TPC of FPs in both mushrooms, particularly after 24 h of fermentation. The TPC of BPs in mushrooms decreased during fermentation, indicating their release from the matrix. Additionally, we identified 30 bioactive compounds using UPLC-Q-TOF-MS/MS. Our study demonstrates for the first time that lactic acid bacteria fermentation of mushrooms with high phenolic content leads to the liberation of bound phenolics, enhancing their bioactivity and bioaccessibility.

Recent progress in promoting the bioavailability of polyphenols in plant-based foods

Polyphenols are important constituents of plant-based foods, exhibiting a range of beneficial effects. However, many phenolic compounds have low bioavailability because of their low water solubility, chemical instability, food matrix effects, and interactions with other nutrients. This article reviews various methods of improving the bioavailability of polyphenols in plant-based foods, including fermentation, natural deep eutectic solvents, encapsulation technologies, co-crystallization and amorphous solid dispersion systems, and exosome complexes. Several innovative technologies have recently been deployed to improve the bioavailability of phenolic compounds. These technologies may be utilized to increase the healthiness of plant-based foods. Further research is required to better understand the mechanisms of action of these novel approaches and their potential to be used in food production.

The Effect of Opuntia ficus Mucilage Pectin and Citrus aurantium Extract Added to a Food Matrix on the Gut Microbiota of Lean Humans and Humans with Obesity

Experimental studies have provided evidence that physicochemical interactions in the food matrix can modify the biologically beneficial effects of bioactive compounds, including their effect on gut microbiota. This work aimed to evaluate the effect of a food gel matrix with Opuntia ficus cladodes mucilage pectin and Citrus Aurantium extract on the growth of four beneficial gut bacteria obtained from the fecal microbiota of people who are lean or who have obesity after digestion in the upper digestive system. To accomplish this, a base formulation of Opuntia ficus cladodes mucilage with or without C. aurantium extract was submitted to an ex vivo fecal fermentation in an automatic and robotic intestinal system. The changes in the intestinal microbiota were determined by means of plate culture and 16S sequencing, while short-chain fatty acids (SCFA) produced in the colon were determined via gas chromatography. In the presence of the extract in formulation, greater growth of Bifidobacterium spp. (+1.6 Log10 Colonic Forming Unit, UFC) and Lactobacillus spp. (+2 Log10 UFC) in the microbiota of lean people was observed. Only the growth in Salmonella spp. (-1 Log10 UFC) from both microbiota was affected in the presence of the extract, which decreased in the ascending colon. SCFA was mainly produced by the microbiota of people who were lean rather than those who had obesity in the presence of the extract, particularly in the ascending colon. The effect of sour orange extract seems to depend on the origin of the microbiota, whether in people who have obesity (25 mM/L) or are lean (39 mM/L).

Influence of lactic acid fermentation on the phenolic profile, antioxidant activities, and volatile compounds of black chokeberry (Aronia melanocarpa) juice

Lactic acid fermentation is an effective method for improving the quality of black chokeberry. This study aimed to investigate the influence of lactic acid bacteria on the phenolic profile, antioxidant activities, and volatiles of black chokeberry juice. Initially, 107  cfu/mL of Lactiplantibacillus plantarum, Lactobacillus acidophilus, and Lacticaseibacillus rhamnosus were inoculated into pasteurized black chokeberry juice and fermented for 48 h at 37°C. All these strains enhanced the total phenolic and total flavonoid contents, with La. acidophilus showing the highest total phenolic (1683.64 mg/L) and total flavonoid (659.27 mg/L) contents. Phenolic acids, flavonoids, and anthocyanins were identified using ultrahigh-performance liquid chromatography-tandem mass spectrometry. The prevalent phenolic acid, flavonoid, and anthocyanin in the lactic-acid-fermented black chokeberry juice were cinnamic acid, rutin, and cyanidin-3-O-rutinoside, respectively. Furthermore, following fermentation, the DPPH and ABTS scavenging capacity, as well as the reducing power capacity, increased from 59.98% to 92.70%, 83.06% to 94.95%, and 1.24 to 1.82, respectively. Pearson's correlation analysis revealed that the transformation of phenolic acids, flavonoids, and anthocyanins probably contributed to enhancing antioxidant activities and color conversation in black chokeberry juice. A total of 40 volatiles were detected in the fermented black chokeberry juice by gas chromatography-ion mobility spectrometry. The off-flavor odors, such as 1-penten-3-one and propanal in the black chokeberry juice, were weakened after fermentation. The content of 2-pentanone significantly increased in all fermented juice, imparting an ethereal flavor. Hence, lactic acid fermentation can effectively enhance black chokeberry products' flavor and prebiotic value, offering valuable insights into their production. PRACTICAL APPLICATION: The application of lactic acid bacteria in black chokeberry juice not only enhances its flavor but also improves its health benefits. This study has expanded the range of black chokeberry products and offers a new perspective for the development of the black chokeberry industry.

Phenolic characterization of fermented jujube puree by HPLC-MS/MS and their release during in vitro dynamic digestion

Health benefits of fruit products fermented with probiotics are partially attributed to their increased contents of phenolic compounds. In this study, the effect of in vitro dynamic gastrointestinal digestion on the release of phenolic compounds and changes in the antioxidant activity of jujube puree fermented with Streptococcus thermophilus was investigated. Thirteen target phenolic compounds were characterized by high-performance liquid chromatography-tandem mass spectrometry. The recovery of this developed method ranged from 87.41% to 111.03%, and the limits of detection and quantification were low. Fermentation with Streptococcus thermophilus significantly increased the contents of most phenolic compounds in jujube puree. Fermentation reduced the decrease in the contents of most phenolic compounds in jujube puree during gastrointestinal digestion and, as a consequence improved the antioxidant capacity of digested fractions. These findings indicated that fermentation could increase the bioaccessibility of specific phenolics in jujube, as well as the antioxidant activity of this fruit.

Influence of Fermentation on Functional Properties and Bioactivities of Different Cowpea Leaf Smoothies during In Vitro Digestion

This study investigated the effects of Lactiplantibacillus plantarum 75 (LAB 75) fermentation at 37 °C for 48 h on the pH, total soluble solids (TSS), colour, total titratable acidity (TTA), carotenoids, and bioactivities of cowpea leaf smoothies from three cultivars (VOP 1, VOP 3, and VOP 4). Fermentation reduced the pH from 6.57 to 5.05 after 48 h. The TTA increased with the fermentation period, whilst the TSS reduced. Fermentation of the smoothies resulted in the least colour changes (∆E) in VOP 1 after 48 h. Fermentation of cowpea smoothies (VOP 1, VOP 3, and VOP 4) improved the antioxidant capacity (FRAP, DPPH, and ABTS), which was attributed to the increase in total phenolic compounds and carotenoid constituents in all of the fermented cowpea smoothies. VOP 1 was further selected for analysis due to its high phenolic content and antioxidant activity. The VOP 1 smoothie fermented for 24 h showed the lowest reduction in TPC (11%) and had the highest antioxidant (FRAP, DPPH, and ABTS) activity. Ltp. plantarum 75 was viable and survived the harsh conditions of the gastrointestinal tract, and, hence, could be used as a probiotic. VOP 1 intestinal digesta showed significantly higher glucose uptake relative to the undigested and the gastric digesta, while the gastric phase had higher levels of α-amylase and α-glucosidase compared to the undigested samples.

Consortia of lactic acid bacteria strains increase the antioxidant activity and bioactive compounds of quinoa sourdough - based biscuits

The aim of this work was to use consortia (two or three strains) of lactic acid bacteria (LAB) [Lactiplantibacillus plantarum CRL 1964 and CRL 1973, and Leuconostoc mesenteroides subsp. mesenteroides CRL 2131] to obtain quinoa sourdoughs (QS) for further manufacturing of quinoa sourdough-based biscuits (QB). Microbial grow and acidification were evaluated in QS while antioxidant activity (AOA), total phenolic compounds (TPC) and total flavonoid compounds (TFC) were determined in QS and QB. QS inoculated with LAB consortia respect to monocultures showed higher growth and acidification, AOA (7.9?42.6%), TPC (19.9?35.0%) and TFC (6.1?31.6%). QB prepared with QS inoculated by LAB consortia showed higher AOA (5.0-81.1%), TPC (22.5?57.5%) and TFC (14.0-79.9%) than biscuits inoculated by monocultures sourdoughs. These results were attributed to a synergic effect from LAB consortia. Principal component analysis showed the highest scores of the evaluated characteristics for biscuits made with consortia sourdough of two (CRL1964?+?CRL2131) and three (CRL1964?+?CRL1973?+?CRL2131) strains.

Conversion of (poly)phenolic compounds in food fermentations by lactic acid bacteria: Novel insights into metabolic pathways and functional metabolites

Lactobacillaceae are among the major fermentation organisms in most food fermentations but the metabolic pathways for conversion of (poly)phenolic compounds by lactobacilli have been elucidated only in the past two decades. Hydroxycinnamic and hydroxybenzoic acids are metabolized by separate enzymes which include multiple esterases, decarboxylases and hydroxycinnamic acid reductases. Glycosides of phenolic compounds including flavonoids are metabolized by glycosidases, some of which are dedicated to glycosides of plant phytochemicals rather than oligosaccharides. Metabolism of phenolic compounds in food fermentations often differs from metabolism in vitro, likely reflecting the diversity of phenolic compounds and the unknown stimuli that induce expression of metabolic genes. Current knowledge will facilitate fermentation strategies to achieve improved food quality by targeted conversion of phenolic compounds.

Aroma profiles of sweet cherry juice fermented by different lactic acid bacteria determined through integrated analysis of electronic nose and gas chromatography-ion mobility spectrometry

Sweet cherries are popular among consumers, with a recent explosion in sweet cherry production in China. However, the fragility of these fruits poses a challenge for expanding production and transport. With the aim of expanding the product categories of sweet cherries that can bypass these challenges, in this study, we prepared sweet cherry juice fermented by three different lactic acid bacteria (LAB; Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus GG), and evaluated the growth, physiochemical, and aroma characteristics. All three strains exhibited excellent growth potential in the sweet cherry juice; however, Lactobacillus acidophilus and Lactobacillus plantarum demonstrated more robust acid production capacity and higher microbial viability than Lactobacillus rhamnosus GG. Lactic acid was the primary fermentation product, and malic acid was significantly metabolized by LAB, indicating a transition in microbial metabolism from using carbohydrates to organic acids. The aroma profile was identified through integrated analysis of electronic nose (E-nose) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) data. A total of 50 volatile compounds characterized the aromatic profiles of the fermented juices by HS-GC-IMS. The flavor of sweet cherry juice changed after LAB fermentation and the fruity odor decreased overall. Lactobacillus acidophilus and Lactobacillus plantarum significantly increased 2-heptanone, ethyl acetate, and acetone contents, bringing about a creamy and rummy-like favor, whereas Lactobacillus rhamnosus GG significantly increased 2-heptanone, 3-hydroxybutan-2-one, and 2-pentanone contents, generating cheesy and buttery-like odors. Principal component analysis of GC-IMS data and linear discriminant analysis of E-nose results could effectively differentiate non-fermented sweet cherry juice and the sweet cherry juice separately inoculated with different LAB strains. Furthermore, there was a high correlation between the E-nose and GC-IMS results, providing a theoretical basis to identify different sweet cherry juice formulations and appropriate starter culture selection for fermentation. This study enables more extensive utilization of sweet cherry in the food industry and helps to improve the flavor of sweet cherry products.

Prospective Role of Indigenous Leafy Vegetables as Functional Food Ingredients

Indigenous leafy vegetables (ILVs) play a pivotal role in sustaining the lives of many people of low socio-economic status who reside in rural areas of most developing countries. Such ILVs contribute to food security since they withstand harsher weather and soil conditions than their commercial counterparts and supply important nutrients such as dietary fibre, vitamins and minerals. Furthermore, ILVs contain bioactive components such as phenolic compounds, flavonoids, dietary fibre, carotene content and vitamin C that confer health benefits on consumers. Several studies have demonstrated that regular and adequate consumption of vegetables reduces risks of chronic conditions such as diabetes, cancer, metabolic disorders such as obesity in children and adults, as well as cardiovascular disease. However, consumption of ILVs is very low globally as they are associated with unbalanced and poor diets, with being food for the poor and with possibly containing toxic heavy metals. Therefore, this paper reviews the role of ILVs as food security crops, the biodiversity of ILVs, the effects of processing on the bioactivity of ILVs, consumer acceptability of food derived from ILVs, potential toxicity of some ILVs and the potential role ILVs play in the future of eating.

Effects of Five Different Lactic Acid Bacteria on Bioactive Components and Volatile Compounds of Oat

In this research, oats were fermented with Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus bulgaricus and Streptococcus thermophilus for 48 h at 37 °C. The purpose of this work was to compare the growth capacities of the five lactic acid bacteria (LAB) in the oat matrix and the effects of fermentation on the contents of the bioactive components of oat, such as β-glucan, polyphenols, flavonoids and volatile compounds at different time (0, 4, 8, 12, 24, 36 and 48 h). After 48 h of fermentation, the number of living L. acidophilus in oat reached 7.05 × 10⁹ cfu/mL, much higher than that of other strains. S. thermophilus retained the greatest β-glucan content, and L. casei had increased total polyphenol and total flavonoid contents. The proportion of free and bound polyphenols and flavonoids in all samples was changed by microbial action, indicating that forms of polyphenols and flavonoids can be transformed during the fermentation process, and the changes varied with different strains. The samples with L. plantarum, L. acidophilus, and L. casei fermentation contained more alcohols, whereas those with S. thermophilus and L. bulgaricus fermentation had more aldehydes, which revealed that the composition of volatile components was related to strains. The results indicate that oat substrate is a good medium for LAB growth. This study provides a reference for the use of different strains to achieve different fermentation purposes and a theoretical basis for the further processing of oat and fermented oat beverages.

The Bioaccessibility and Antioxidant Activities of Fermented Mango Cultivar Juices after Simulated In Vitro Digestion

The purpose of this study was to investigate the bioaccessibilities of total phenolic compounds, carotenoid profile, antioxidant activity, and Lactic acid bacteria (LAB) survival in fermented mango juice (MJs) obtained from three mango cultivars after exposure to an in vitro gastrointestinal digestion model. The MJs from three cultivars ('Sabre', 'Peach', and 'Tommy Atkins') were fermented using Lactiplantibacillus plantarum 75 (L75), Leuconostoc pseudomesenteroides 56 (L56), and their combination (L56 + 75). Fermented MJs were digested and fractions: gastric (GF), intestinal (IF), and dialysis (DF) were analyzed for total polyphenolic content (TPC), antioxidant activity (FRAP), 1-diphenyl-2-picrylhydrazyl (DPPH), and 2.2-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS). In addition, the carotenoid content and the LAB population were determined from the GF and IF. After digestion, TPC decreased while fermentation improved its bioaccessibility. L75-fermented 'Sabre' MJs had the highest bioaccessible TPC in the GF (75.65%), IF (50.10%), and DF (32.52%) while L56 'Peach' MJs increased the β-carotene bioaccessibility by 1.32-fold at GF and IF (1.21-fold). When compared to the other two juices, 'Sabre' and 'Peach' MJs fermented with L75 showed the highest IC₅₀ values for DPPH and ABTS. Generally, L75-fermented 'Sabre' MJs had the highest LAB survival at both GF (7.57 Log CFU/mL) and IF (7.45 Log CFU/mL) and hold potential as probiotic juices. L56-fermented 'Sabre' MJs would ensure the delivery of four times the carotenoid recommended dietary allowance (RDA) to a target site in the body while L75-fermented 'Peach' MJs could be used to effectively counteract oxidants in the body system.

Effect of lactic acid fermentation on the nutritional quality and consumer acceptability of African nightshade

African nightshade (ANS) is among many underexploited and neglected indigenous vegetables. This study assessed the effect of lactic acid fermentation (LAF) on nutritional and sensory quality in Solanum villosum (Sv) and Solanum scabrum (Ss). Spontaneously fermented (SF) and controlled fermented (CF) conditions using Lactobacillus plantarum LP90 and Leuconostoc mesenteroides LM58 were employed for 15 days and 120 h. From the fermented pickles, relish products were prepared using cooking oil and a variety of spices. The relish products were subjected to a consumer acceptability test. Results show a significant drop in pH to <3.5, increasing titratable acidity (TTA) to around 0.6 after 120 h and 15 days of CF and SF, respectively. LAF resulted in a 2.6-5 and 1.6-4.8-fold significant rise in β-carotene in pickles and their relish products. All pickles and relish products exhibited a significant decrease (p < .05) in vitamin C by 88.33%-95.90%. LAF significantly reduced total phenolic (26%- 43%) and Chlorophyll (16.45%-39.25%). On the other hand, LAF showed improvement in minerals content (P, Ca, Fe, and Zn) and reduction of tannin (76.27%-92.88%) and oxalate (77.33%-90%) levels. LAF relish products were highly preferred by the consumers, with S. villosum controlled fermented relish (SvCFR) leading. All fermented relishes were stable at ambient (27°C) and refrigeration (4°C) temperatures after 6 months of storage. Generally, LAF is an effective method for ANS preservation, with improved nutritional quality and safety. LAF can therefore be recommended to small-scale farmers, processors, and households for ANS preservation. Ultimately, this method enhances the nutrition and sensory quality, safety, and livelihood.

Lentil-Based Yogurt Alternatives Fermented with Multifunctional Strains of Lactic Acid Bacteria-Techno-Functional, Microbiological, and Sensory Characteristics

A milk-alternative produced from lentil protein isolate was fermented with three multifunctional strains of lactic acid bacteria, Leuconostoc citreum TR116, Leuconostoc pseudomesenteroides MP070, and Lacticaseibacillus paracasei FST 6.1. As a control, a commercial starter culture containing Streptococcus thermophilus was used. The metabolic performance of these strains and the techno-functional properties of the resulting yogurt alternatives (YA) were studied. Microbial growth was evaluated by cell counts, acidification, and carbohydrate metabolization. The structure of the YA was investigated by textural and rheological analyses and confocal laser scanning microscopy (CLSM). Production of antifungal compounds, the influence of fermentation on the content of FODMAPs, and typical metabolites were analyzed, and a sensory analysis was performed. The results revealed an exponential microbial growth in the lentil base substrate supported by typical acidification, which indicates a suitable environment for the selected strains. The resulting YA showed a gel-like texture typical for non-stirred yogurts, and high water holding capacity. The tested strains produced much higher levels of antifungal phenolic compounds than the commercial control and are therefore promising candidates as adjunct cultures for shelf-life extension. The Leuconostoc strains produced mannitol from fructose and could thus be applied in sugar-reduced YA. Preliminary sensory analysis showed high acceptance for YA produced with Lacticaseibacillus paracasei FST 6.1, and a yogurt-like flavor not statistically different to that produced by the control. Overall, each tested strain possessed promising functionalities with great potential for application in fermented plant-based dairy-alternatives.

Fate of Bioactive Compounds during Lactic Acid Fermentation of Fruits and Vegetables

Consumption of lactic acid fermented fruits and vegetables has been correlated with a series of health benefits. Some of them have been attributed to the probiotic potential of lactic acid microbiota, while others to its metabolic potential and the production of bioactive compounds. The factors that affect the latter have been in the epicenter of intensive research over the last decade. The production of bioactive peptides, vitamins (especially of the B-complex), gamma-aminobutyric acid, as well as phenolic and organosulfur compounds during lactic acid fermentation of fruits and vegetables has attracted specific attention. On the other hand, the production of biogenic amines has also been intensively studied due to the adverse health effects caused by their consumption. The data that are currently available indicate that the production of these compounds is a strain-dependent characteristic that may also be affected by the raw materials used as well as the fermentation conditions. The aim of the present review paper is to collect all data referring to the production of the aforementioned compounds and to present and discuss them in a concise and comprehensive way.

Influence of Lactic Acid Bacterium Strains on Changes in Quality, Functional Compounds and Volatile Compounds of Mango Juice from Different Cultivars during Fermentation

The effects of lactic acid fermentation using Lactiplantibacillus plantarum 75 (L75), Leuconostoc pseudomesenteroides 56 (L56) and its combination (L56 + 75) on the quality, bioactive and volatile compounds of mango juices (MJ) from three cultivars (‘Peach’, ‘Sabre’ and ‘Tommy Atkins’) were investigated. Fermented and unfermented MJ were evaluated for LAB growth, physicochemical parameters, volatile compounds, antioxidants activities (DPPH, ABTS, FRAP methods), total phenolic content (TPC) and sensory properties. The unfermented juices served as a control. Twenty-four-hour fermentation was ideal for MJ based on LAB growth profiles. Generally, titratable acidity, TPC, FRAP, DPPH and ABTS scavenging activities significantly increased with fermentation by the L75 strain and were highest in the L75-fermented ‘Sabre’ MJ, while L75-fermented ‘Peach’ MJ had higher ABTS activity (p < 0.05). In contrast, the L56 strain enhanced β-carotene retention, with improved colour properties in L56-fermented ‘Peach’ MJ. Fermentation with L75 in ‘Sabre’ and ‘Peach’ MJ aided the synthesis of new volatile compounds (alcohols, esters, ketones and aldehydes). A PLS-DA scatter plot showed two clusters separating the ‘Peach’ and ‘Sabre’ mango juice fermented with L75 from the rest. Based on the variable importance of the projection value (VIP) scores, pentadecane, 8-hexyl and butyl isobutyrate were shown as marker candidates to distinguish ‘Peach’ and ‘Sabre’ MJ fermented with L75 from the other treatments, whereas ethyl octanoate and isobutyl acetate differentiated the ‘Sabre’ MJ fermented with L75 from the other treatments. ‘Sabre’ and ‘Peach’ MJ fermented with L75 and L56 could provide antioxidants, meeting the recommended daily requirements for ascorbic acid and carotenoids in adults and teenagers. Hence, lactic acid fermentation of these local cultivars is a way to benefit consumers.

Evolution of microbial communities and nutritional content of fermented Amaranthus sp. leaves

Amaranth (Amaranthus sp.) is a promising indigenous leafy vegetable plant capable of contributing to food security in sub-Saharan Africa, thanks to its adaptability to diverse soils and its drought tolerance. Its edible parts such as leaves are characterized by high nutrient content. Food losses along the supply chain due to spoilage, however, especially of fresh produce is a challenge facing most of the sub-Saharan African countries in tackling food insecurity in the region. This calls for innovative yet inexpensive solutions such as natural fermentation to preserve the quality and safety of the commodity. To demonstrate the feasibility of natural fermentation in the preservation of vegetable amaranth, leaves were submerged (1:0.5 w/v) in distilled water with 3% sucrose and 3% NaCl dissolved. Control batches were prepared using only distilled water (1:0.5 w/v) with amaranth leaves. Samplings of both treated leaves and controls occurred at 0, 24, 48, 72, and 168 h to measure the pH and determine microbial population changes using culture and molecular-based techniques. Furthermore, the effects of treatment on nutritional content were assayed at the end of the process to determine the levels of B-group vitamins, β-carotene, lutein, and anti-nutrient phytic acid from unfermented fresh air-dried and 3% sucrose and 3% NaCl treated amaranth leaves. Finally, a visive and olfactive analysis was carried out to evaluate the acceptability of the final product. The significant drop of pH and the correct growth of Lactobacillaceae occurred only in treated batches, although Lactococcus was found in both treated and control samples. Furthermore, mean counts observed on selective media for controls and molecular high-throughput sequencing (HTS) analyses confirmed that in control samples, the undesired bacteria represented more than 60% of the microbial population. In treated amaranth leaves the amount of thiamin, riboflavin, vitamin B₆, β-carotene and lutein content were higher compared to the fresh unfermented air-dried leaves, and phytic acid content diminished after 7-days treatment. These findings suggest that treatment of amaranth leaves using 3% sucrose and 3% NaCl does not only preserve the commodity by arresting the growth of undesired microorganisms involved in spoilage and fosters the lactic acid bacteria but also improves the nutritional content of the fermented end product that has been warmly welcomed by panelists.

Submerged fermentation improves bioactivity of mulberry fruits and leaves

Objective

Mulberry (Morus spp.) fruits and leaves have been proven to possess nutraceutical properties. Due to its fast and easy growing characteristics, mulberry fruits (MF) and leaves (ML) potentially emerge as a great source of functional foods. This study aims to enhance bioactivities (antioxidant, anti-inflammation, and hypoglycemic activity) of MF and ML via submerged fermentation using bacteria (Lactobacillus plantarum TAR 4), yeast (Baker’s yeast and red yeast) and fungi (Tempeh and Tapai starter).

Methods

In this study, 25% (mass to volume ratio) of MF and ML were fermented (48 h) with 1% (mass to volume ratio) of different microbial cultures, respectively. Effects of different fermentations on MF and ML were determined based on the changes of total phenolics (TPC), flavonoids (TFC), anthocyanins, total sugar, DPPH activity, ferric reducing antioxidant power (FRAP), albumin denaturation inhibition activity (ADI), anti-lipoxygenase activity and α-amylase inhibition activity (AI).

Results

Generally, ML had higher AI than MF. However, MF exhibited higher DPPH, FRAP and anti-lipoxygenase activity than ML. After all forms of fermentation, DPPH and AI activity of MF and ML were increased significantly (P < 0.05). However, the effects of fermentation on TPC, FRAP, ADI and anti-lipoxygenase activity of MF were in contrast with ML. TPC, FRAP and anti-lipoxygenase activity of ML were enhanced, but reduced in MF after fermentation. Although the effects exerted by different microorganisms in MF and ML fermentation were different, the bioactivities of MF and ML were generally improved after fermentation. Fermentation by Tempeh starter enhanced TPC (by 2-fold), FRAP (by 2.3-fold), AI (at 10% increment) and anti-lipoxygenase activity (by 5-fold) of ML, whereas Tapai fermentation effectively enhanced the DPPH (at 17% increment) and ADI (by 2-fold) activity of MF.

Conclusion

Findings of this study provide an insight into the future process design of MF and ML processing into novel functional foods.

African nightshades (Solanum nigrum complex): The potential contribution to human nutrition and livelihoods in sub-Saharan Africa

Achieving zero hunger in sub-Saharan Africa (SSA) without minimizing postharvest losses of agricultural products is impossible. Therefore, a holistic approach is vital to end hunger, simultaneously improving food security, diversity, and livelihoods. This review focuses on the African nightshades (ANS) Solanum spp. contribution to improving food and nutrition security in SSA. Different parts of ANS are utilized as food and medicine; however, pests and diseases hinder ANS utilization. African nightshade is rich in micronutrients such as β-carotene, vitamins C and E, minerals (iron, calcium, and zinc), and dietary fiber. The leaves contain a high amount of nutrients than the berries. Proper utilization of ANS can contribute to ending hidden hunger, mainly in children and pregnant women. Literature shows that ANS contains antinutritional factors such as oxalate, phytate, nitrate, and alkaloids; however, their quantities are low to cause potential health effects. Several improved varieties with high yields, rich in nutrients, and low alkaloids have been developed in SSA. Various processing and preservation techniques such as cooking, drying, and fermentation are feasible techniques for value addition on ANS in SSA; moreover, most societies are yet to adopt them effectively. Furthermore, promoting value addition and commercialization of ANS is of importance and can create more jobs. Therefore, this review provides an overview of ANS production and challenges that hinder their utilization, possible solutions, and future research suggestions. This review concludes that ANS is an essential nutritious leafy vegetable for improving nutrition and livelihoods in SSA.

Fermentation of Jamaican Cherries Juice Using Lactobacillus plantarum Elevates Antioxidant Potential and Inhibitory Activity against Type II Diabetes-Related Enzymes

Jamaican cherry (Muntinga calabura Linn.) is tropical tree that is known to produce edible fruit with high nutritional and antioxidant properties. However, its use as functional food is still limited. Previous studies suggest that fermentation with probiotic bacteria could enhance the functional properties of non-dairy products, such as juices. In this study, we analyze the metabolite composition and activity of Jamaican cherry juice following fermentation with Lactobacillus plantarum FNCC 0027 in various substrate compositions. The metabolite profile after fermentation was analyzed using UPLC-HRMS-MS and several bioactive compounds were detected in the substrate following fermentation, including gallic acid, dihydrokaempferol, and 5,7-dihydroxyflavone. We also found that total phenolic content, antioxidant activities, and inhibition of diabetic-related enzymes were enhanced after fermentation using L. plantarum. The significance of its elevation depends on the substrate composition. Overall, our findings suggest that fermentation with L. plantarum FNCC 0027 can improve the functional activities of Jamaican cherry juice.

Changes in Phenols, Polysaccharides and Volatile Profiles of Noni (Morinda citrifolia L.) Juice during Fermentation

The change in phenols, polysaccharides and volatile profiles of noni juice from laboratory- and factory-scale fermentation was analyzed during a 63-day fermentation process. The phenol and polysaccharide contents and aroma characteristics clearly changed according to fermentation scale and time conditions. The flavonoid content in noni juice gradually increased with fermentation. Seventy-three volatile compounds were identified by solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC-MS). Methyl hexanoate, 3-methyl-3-buten-1-ol, octanoic acid, hexanoic acid and 2-heptanone were found to be the main aroma components of fresh and fermented noni juice. A decrease in octanoic acid and hexanoic acid contents resulted in the less pungent aroma in noni juice from factory-scale fermentation. The results of principal component analysis of the electronic nose suggested that the difference in nitrogen oxide, alkanes, alcohols, and aromatic and sulfur compounds, contributed to the discrimination of noni juice from different fermentation times and scales.

Influence of Fermentation of Pasteurised Papaya Puree with Different Lactic Acid Bacterial Strains on Quality and Bioaccessibility of Phenolic Compounds during In Vitro Digestion

This study describes the impact of utilising different strains of lactic acid bacteria (LAB) for the fermentation of papaya puree and their effect on the quality parameters and bioaccessibility of phenolic compounds during simulated in vitro gastrointestinal digestion. Papaya was processed into puree; pasteurised and fermented at 37 °C for 2 days; and stored for 7 days at 4 °C using LAB strains Lactiplantibacillus plantarum 75 (L75*D2; L75*D7), Weissella cibaria64 (W64*D2; W64*D7) and Leuconostoc pseudomesenteroides 56 (L56*D2; L56*D7), respectively. Non-fermented samples at 0 (PPD0), 2 (PPD2) and 7 days (PPD7) served as controls. pH was reduced with fermentation and was lowest in L56*D2 (3.03) and L75*D2 (3.16) after storage. The colour change (ΔE) increased with the fermentation and storage of purees; L75*D7 showed the highest ΔE (13.8), and its sourness reduced with storage. The fermentation by W64*D7 and L75*D7 increased the % recovery of chlorogenic, vanillic, syringic, ellagic, ferulic acids, catechin, epicatechin and quercetin in the intestinal fraction compared to the L56*D7 and PPD7. Fermentation by W64*D7 and L75*D7 significantly improved the antioxidant capacity of the dialysed fraction compared to the L56*D7 or PPD7. L56*D7-fermented papaya puree showed the highest inhibitory effect of α-glucosidase activity followed by L75*D7. L75*D7 had a significantly higher survival rate. LAB fermentation affected the bioacessibilities of phenolics and was strain dependent. This study recommends the use of Lpb. plantarum 75 for fermenting papaya puree.

Editorial for Special Issue "Lactic Acid Bacteria, Biopreservation Agents for Fruit and Vegetables"

Amongst the microbial diversity in the food chain, lactic acid bacteria (LAB) are in the front row for their positive roles [...].

Physicochemical Parameters and Bioaccessibility of Lactic Acid Bacteria Fermented Chayote Leaf (Sechium edule) and Pineapple (Ananas comosus) Smoothies

In this study, popularly consumed traditional chayote leaves and locally produced pineapple fruit were used to develop a fermented smoothie using lactic acid bacteria (LAB) strains: Lactobacillus plantarum (L75), Weissella cibaria (W64), and their combination (LW64 + 75). The physicochemical parameters [pH, total soluble solids (TSS), and color], total phenols, and carotenoid contents of the smoothies fermented for 48 h and stored for 7 days at 4°C were compared with the unfermented (control) smoothies. Results indicated that LAB fermentation reduced the pH from 3.56 to 2.50 after 48 h (day 2) compared with the non-fermented smoothie at day 2 (pH 3.37). LAB strain L75 significantly reduced the TSS content of the smoothies to 13.06°Bx after 2 days of fermentation. Smoothies fermented by L75 showed overall acceptability after 7 days of storage compared with the non-fermented puree on day 0. The LW64 + 75 significantly reduced the color change (ΔE), which was similar to the control. L75 increased the phenolic content, and W64 enhanced the total carotenoid content of the smoothies after 2 days of fermentation compared with other treatments. The use of an in vitro model simulating gastrointestinal (GI) digestion showed that fermentation with L75 improved the total phenol recovery by 65.96% during the intestinal phase compared with the control. The dialysis phase mimicked an epithelial barrier, and 53.58% of the recovered free soluble are bioavailable from the L75 fermented smoothies compared with the control. The antioxidant capacity of dialyzable fraction of the L75 fermented smoothie was significantly higher than that of the control and smoothies fermented with W64 or LW64 + 75.

Evaluation of Semi-Solid-State Fermentation of Elaeocarpus serratus L. Leaves and Black Soymilk by Lactobacillus plantarum on Bioactive Compounds and Antioxidant Capacity

Elaeocarpus serratus L. leaves (EL) containing phenolic compounds and flavonoids, including myricitrin with pharmacological properties, could be valorized as nutritional additive in foods. In this study, the semi-solid-state fermentation of EL and black soymilk (BS) by Lactobacillus plantarum BCRC 10357 was investigated. Without adding EL in MRS medium, the β-glucosidase activity of L. plantarum quickly reduced to 2.33 ± 0.15 U/mL in 36 h of fermentation; by using 3% EL, the stability period of β-glucosidase activity was prolonged as 12.94 ± 0.69 U/mL in 12 h to 13.71 ± 0.94 in 36 h, showing positive response of the bacteria encountering EL. Using L. plantarum to ferment BS with 3% EL, the β-glucosidase activity increased to 23.78 ± 1.34 U/mL in 24 h, and in the fermented product extract (FPE), the content of myricitrin (2297.06 μg/g-FPE) and isoflavone aglycones (daidzein and genistein, 474.47 μg/g-FPE) at 48 h of fermentation were 1.61-fold and 1.95-fold of that before fermentation (at 0 h), respectively. Total flavonoid content, myricitrin, and ferric reducing antioxidant power in FPE using BS and EL were higher than that using EL alone. This study developed the potential fermented product of black soymilk using EL as a nutritional supplement with probiotics.

Phytochemical and Nutritional Quality Changes During Irrigation and Postharvest Processing of the Underutilized Vegetable African Nightshade

Underutilized or traditional leafy vegetables are grown in the wild and cultivated. They are consumed as nutritional accompaniments to staples, either raw (fresh), cooked, or in a dried form, through custom, habit, and tradition. These traditional leafy vegetables are natural rich sources of phytochemicals and nutritional compounds. Over time, the keenness for consumption of traditional vegetables has become less popular. Poor nutrient diets are the main cause of mortality and morbidity, especially in developing countries, where the problem is predominant due to poverty. Consumption of traditional vegetables can assist in the prevention of chronic disease development, as they contain various bioactive compounds that exhibit multiple health benefits. Traditional leafy vegetables play a vital role in combatting hunger, food insecurity, and malnutrition, and most are suitable for food intervention programs. African nightshade (Solanum family) is one such commonly consumed traditional leafy vegetable. During dry seasons, communities often face shortages of vegetables; thus, the preservation of edible leaves is one strategy to help overcome this problem. The adoption of solar drying and fermentation are traditional methods to extend the availability of African nightshade vegetables. Additionally, the agronomy practices and postharvest processing methods affect the phytochemicals and nutritional compounds of African nightshade accessions. This mini-review provides information on changes in phytochemicals, nutrition, and antinutritive compounds with different postharvest processing methods and irrigation. The review provides the justification to promote the cultivation for consumption, by identifying the potential African nightshade accessions that are rich in phytonutritional compounds. This mini-review summarizes and discusses the major information on (i) the micro- and macronutrients present in Solanum retroflexum, the most commonly consumed nightshade species compared with other traditional vegetables in Southern Africa, (ii) the composition of phytochemical compounds present in different nightshade accessions, (iii) the impact of irrigation on phytochemical composition in different nightshade species, and (iv) the impact of postharvest processing on phytochemicals and antinutritive compounds in S. retroflexum. Inclusion of African nightshade, especially S. retroflexum, with the main staple foods can improve protein, iron, and calcium levels in daily diets, which will help to improve people's health and well-being.