Bound phenolics in foods, a review

Comparative analysis of the morphological property and chemical composition of soluble and insoluble dietary fiber with bound phenolic compounds from different algae

The morphological, physicochemical, and biochemical properties of soluble and insoluble dietary fiber from seven types of algae were investigated. The soluble dietary fiber (SDF) contents (6.48 to 60.90% of the total fiber) in most of the investigated algae were significantly lower than the insoluble dietary fiber (IDF) contents (39.10 to 93.52% of the total fiber). It can be inferred from the infrared and UV-Vis spectra that the SDF and IDF of algae may contain cellulose, hemicellulose, various monosaccharides, phenolic compounds, and quinone pigments. The bound phenolic in the seven algae varied widely in contents (3.76 to 14.08 mg GAE/g in IDF and 1.94 to 8.61 mg GAE/g in SDF), whose antioxidant activities in the IDF were stronger than those in SDF because of different phenolic compositions. The HPLC-mass spectrometry (MS)/MS results showed that the IDF may contain methyl-8α-hydroxy-grindelate-7β-O-7'β-ether hydrate, hydroxydecanoic acid, and malyngic acid. PRACTICAL APPLICATION: Polysaccharides of high content in algae cannot be digested by humans, hence regarded as dietary fibers. A large amount of bound phenolic compounds in dietary fibers can add to the biological activities of dietary fibers. These topics are important to the development of seaweed-based functional foods.

Processing Factors Affecting the Phytochemical and Nutritional Properties of Pomegranate (Punica granatum L.) Peel Waste: A Review

Pomegranate peel has substantial amounts of phenolic compounds, such as hydrolysable tannins (punicalin, punicalagin, ellagic acid, and gallic acid), flavonoids (anthocyanins and catechins), and nutrients, which are responsible for its biological activity. However, during processing, the level of peel compounds can be significantly altered depending on the peel processing technique used, for example, ranging from 38.6 to 50.3 mg/g for punicalagins. This review focuses on the influence of postharvest processing factors on the pharmacological, phytochemical, and nutritional properties of pomegranate (Punica granatum L.) peel. Various peel drying strategies (sun drying, microwave drying, vacuum drying, and oven drying) and different extraction protocols (solvent, super-critical fluid, ultrasound-assisted, microwave-assisted, and pressurized liquid extractions) that are used to recover phytochemical compounds of the pomegranate peel are described. A total phenolic content of 40.8 mg gallic acid equivalent (GAE)/g DM was recorded when sun drying was used, but the recovery of the total phenolic content was higher at 264.3 mg TAE/g when pressurised liquid extraction was performed. However, pressurised liquid extraction is costly due to the high initial investment costs and the limited possibility of carrying out selective extractions of organic compounds from complex peel samples. The effects of these methods on the phytochemical profiles of pomegranate peel extracts are also influenced by the cultivar and conditions used, making it difficult to determine best practice. For example, oven drying at 60 °C resulted in higher levels of punicalin of 888.04 mg CE/kg DM compared to those obtained 40 °C of 768.11 mg CE/kg DM for the Wonderful cultivar. Processes that are easy to set up, cost-effective, and do not compromise the quality and safety aspects of the peel are, thus, more desirable. From the literature survey, we identified a lack of studies testing pretreatment protocols that may result in a lower loss of the valuable biological compounds of pomegranate peels to allow for full exploitation of their health-promoting properties in potentially new value-added products.

Effect of Baking Time and Temperature on Nutrients and Phenolic Compounds Content of Fresh Sprouts Breadlike Product

Sprouting has received increasing attention because of the enhanced nutritional values of the derived products. Baking affects the nutrient availability of the end products. The aim of this study was to evaluate how different baking time and temperature affect the nutritional values of bakery products derived from fresh wheat sprouts. Results indicate that the breadlike products showed comparable total polyphenol content and the thermal processes affected the free and bound fractions. Low temperature and high exposure time appear to promote the availability of the free polyphenols and sugars, while high temperature and low exposure time appear to preserve bound polyphenols and starch. Sugar profiles were influenced by baking programs with a higher simple sugar content in the samples processed at low temperature. Phenolic acids showed a strong decrease following processing, and free and bound phenolic acids were positively influenced by high baking temperatures, while an opposite trend was detected at low temperatures. Significant differences in phenolic acid profiles were also observed with a redistribution of hydroxycinnamic acids among the bound and free fractions. It may be concluded that grain type, germination conditions, and the baking programs play a fundamental role for the production of high-nutritional-value bakery products.

BY-PRODUCTS OF PROCESSING CAROB MOLASSES AS SOURCES OF DIETARY FIBRE AND POLYPHENOLS

Dietary fibre and polyphenols have been widely used to increase the functionality of some foods because of their potential  effects on human health. In this study, extraction of dietary fibre and polyphenols from pomace obtained as a by-product of processing carob molasses has been studied. The dietary fibre and polyphenol extracts were prepared separately. The amount of dietary fibre in the carob molasses pomace was evaluated with two assays: the Association of Official  Analytical Chemists’ enzymatic-gravimetric method and the enzymatic-chemical method. The methods were compared, each having been preceded by conventional extraction and ultrasound-assisted extraction of carob  molasses pomace. It has been found that when the enzymatic-gravimetric method and the ultrasound-assisted extraction method were used, the total dietary fibre contents were significantly higher than after using the enzymatic-chemical method and the conventional extraction method. Conventional extraction of polyphenols from carob molasses pomace has shown a relatively higher polyphenol content and antioxidant activity than ultrasound-assisted extraction. Ultrasound-assisted extraction  took  less time than conventional extraction did. The polyphenol profile was characterised by means of a high-performance liquid-chromatography diode array detector using 10 phenolic standards. Six compounds, i.e. caffeic, syringic, -epicatechin, trans-cinnamic  acid,  myricetin,  and naringin were determined with the high-performance liquid chromatography-diode array detector using both conventional extraction and the ultrasound-assisted extraction. Our results suggest that carob molasses pomace can be used to prepare low-calorie, high-fibre, and antioxidant-rich foods, nutraceuticals, and pharmaceuticals.

Regulation of phenolic release in corn seeds (Zea mays L.) for improving their antioxidant activity by mix-culture fermentation with Monascus anka, Saccharomyces cerevisiae and Bacillus subtilis

In this study, mix-culture fermentation (MF) with M. anka, S. cerevisiae and B. subtilis to regulate phenolic release in corn seeds was investigated. Results showed the adding strategy of S. cerevisiae and B. subtilis significantly (p < 0.05) influenced the total phenolic content (TPC) of corn seeds, and the highest TPC in MF was 22.56-fold rise than that of unfermented control. Moreover, the phenolic compounds in corn seeds were shifted after MF. SDS-PAGE revealed some enzymes produced by microorganisms were regulated, and the α-amylase and FPase activities were changed to improvement in MF. SEM micrographs of corn seeds in MF varied markedly with the cell walls structure destroyed, so as to release of the phenolic fractions in corn seeds. Based on the phenolic mobilization, DPPH and ABTS⁺ radical scavenging abilities of phenolic fractions from corn seeds were improved in MF. This paper provides a prospect fermentation process for improving the phenolic release in corn cereals.

Optimization of Extraction Conditions to Improve Phenolic Content and In Vitro Antioxidant Activity in Craft Brewers' Spent Grain Using Response Surface Methodology (RSM)

Extraction temperature, extraction time and liquid (water) to solid ratio were optimized in order to extract antioxidant phenolic compounds from brewers’ spent grain (BSG). The extracts were analysed for their total phenol content (TPC) and antioxidant activity was measured using three different methods: 2,2-diphenyl-2-picrylhydrazyl (DPPH) free radical, 2,2′-azino-bis(3-ethylbenothiazoline-6-sulphonic acid) (ABTS), and reducing power (RP) assays. All the parameters except extraction time promoted different efficiencies for the extraction of antioxidant phenolic compounds. TPC extraction was higher at lower temperatures and lower liquid/solid ratios up to a certain point. In this sense, a decrease in TPC with increasing liquid/solid ratios took place until a 16:1 ratio and a plateau was reached beyond that ratio. The highest DPPH activity was reported for 30–35 °C and 60–90 min extraction and 60–90 min extraction with a 25 mL/g ratio. ABTS values increased as the liquid to solid ratio decreased, being positively correlated with TPC (R = 0.788; p < 0.01). The highest RP was achieved at 30–33 °C extraction temperature and 10–14 mg/mL v/w ratio and at 116–120 min extraction and 16–17 mg/mL ratio. Gallic acid accounted for the majority of the phenolic compounds found, followed by hydroxyphenylacetic acid, epicatechin, and protocatechuic acid. Sinapic, 4-hydroxy benzoic, and syringic acids were also found in lower quantities. Coumaric, vanillic, ferulic, and caffeic acids were present in very small amounts. All the extracts contained phenolics and showed in vitro antioxidant activity, but the extracts obtained by using 30 °C, 121.9 min, and 10 mL/g liquid/solid ratio exhibited the highest content in TPC and antioxidant potential. The aqueous extraction of a potentially bioactive extract from BSG was demonstrated to be an efficient and simple method to recover these value-added compounds.

Comparative assessment of functional properties, free and bound phenolic profile, antioxidant activity, and in vitro bioaccessibility of rye bran and its insoluble dietary fiber

In cereals, 95% of dietary fiber is associated with phenolic compounds. The present study examined the functional properties, phenolic composition, antioxidant activity, and in vitro bioaccessibility of phenolics and flavonoids present in rye bran (RB) and its insoluble dietary fiber (IDF). Compared to RB, higher functional properties (WHC, WRC, and OHC) were represented by IDF due to its porous structure. The IDF contained lower free but higher bound phenolics and flavonoids content as compared to RB, whereas highest total phenolics (556.6 mg GAE/100 g) and flavonoids (378.3 mg RE/100 g) content were observed in IDF. Results had identified significant differences (p < .05) in phenolic acids composition between RB and IDF determined by HPLC-MS and the total phenolic acids were higher in IDF. The antioxidant capacity of IDF was higher than RB in DPPH, FRAP, ABTS, and reducing power assay. However, the in vitro phenolics and flavonoids bioaccessibility of IDF was much lower because of its high content of bound phenolics and flavonoids. PRACTICAL APPLICATIONS: A successful comparative study between RB and its IDF has been conducted in this research work that edifies the health benefits associated with the phytochemicals linked with RB and IDF. The present study also carries rich information regarding the cereal chemistry of RB that truly facilitates the food developers to specifically focus on the bioaccessibility of phenolic compounds present in IDF and RB. The findings about the functional properties and antioxidant capacities of RB and its IDF can also open new research horizons when dealing with food product development tasks, specifically related to therapeutic and medically tailored meals for the targeted customers.

Main bioactive phenolic compounds in marine algae and their mechanisms of action supporting potential health benefits

Given the growing tendency of consumers to choose products with natural ingredients, food industries have directed scientific research in this direction. In this regard, algae are an attractive option for the research, since they can synthesize a group of secondary metabolites, called phenolic compounds, associated with really promising properties and bioactivities. The objective of this work was to classify the major phenolic compounds, compare the effectiveness of the different extractive techniques used for their extraction, from traditional systems (like heat assisted extraction) to the most advance ones (such as ultrasound, microwave or supercritical fluid extraction); the available methods for identification and quantification; the stability of the enriched extract in phenolic compounds and the main bioactivities described for these secondary metabolites, to offer an overview of the situation to consider if it is possible and/or convenient an orientation of phenolic compounds from algae towards an industrial application.

Acetic acid buffer as extraction medium for free and bound phenolics from dried blackcurrant (Ribes nigrum L.) skins

The aim of this study was to investigate the effects of different solvent and extraction temperatures on the free and bound phenolic compounds and antioxidant activity of dried blackcurrant skins (DBS). Apart from acetic acid buffer solution, different solvent systems, including water, methanol, and mixtures of methanol/water, were also employed and the effects of solvent and temperature (30 and 50 °C) on the free and bound forms of anthocyanins, hydroxycinnamic acids, and flavonols yield were assessed. The results showed that among all solvents, acetic acid buffer resulted in the highest free anthocyanin content (1,712.3 ± 56.1 mg/100 g) (P < 0.05) after 2 hr extraction at 50 °C from DBS, while lower amounts of bound anthocyanins and anthocyanidins were detected after acid hydrolysis. Acetic acid buffer extracts exhibited the highest free hydroxycinnamic acid content (268.0 ± 4.5 mg/100 g), total phenolic content (3702.2 ± 259.3 mg GAE/100 g), and DPPH activity (60.7 ± 2.0% of inhibition). However, their free flavonol content was slightly lower (60.2 ± 0.8 mg/100 g) compared to 100% methanol at 30 and 50 °C (71.4 ± 1.5 mg/100 g and 71.5 ± 6.2 mg/100 g, respectively). Two-way ANOVA indicated interactions between solvent and temperature (P < 0.05), which suggested that the relationship between solvent and phenolic compounds depends on the extraction temperature. PRACTICAL APPLICATION: Overall, acetic acid buffer is more environmental friendly, efficient, and cost effective than other solvents, thus, offering an improved extraction method for phytochemicals as valuable ingredients for nutraceutical applications, from underutilized dried blackcurrant skins (DBS).

Development of arrowroot flour fermented by kefir grains

The present study aims to produce arrowroot flour fermented by kefir grains, in addition to assessing the physicochemical, nutritional, and microbiological characteristics. Fermented arrowroot flour was produced at room temperature (approximately 25 to 28 °C). Fermentation was conducted in batch (6 kg of the substrate and 10% of kefir grains were added with homogenization every 3 hr). Samples were evaluated every 12 hr for both fermentation processes (fermentation process 1: 24 hr and fermentation process 2: 48 hr). The flours were evaluated for physicochemical, nutritional, and microbiological qualities, using a completely randomized design, considering only the variation in the duration of both fermentation processes (from 24 to 48 hr). The fermentation process positively modified the physicochemical, nutritional, and microbial characteristics of the flours. An increase in antioxidant activity (IC₅₀ : control flour [CF] = 18.9 ± 0.13; arrowroot kefir flour [24 hr of fermentation; AKF1] = 15.36 ± 0.14; and arrowroot kefir flour [48 hr of fermentation; AKF2] = 13.84 ± 0.15), protein percentage (CF = 3.08 ± 0.12; AKF1 = 4.87 ± 0.33; and AKF2 = 6.00 ± 0.07), and organic acid (lactic, acetic, and propionic acids) production was observed, as well as modification in color (browning), the conformation of starch structures, and carbohydrate reduction. These results suggested that the "arrowroot kefir flours" open a new perspective for introduction in the market as a new product that can be used as food in nature or food ingredient for making bread, biscuits, pasta, and others, showing microbiological safety and functions properties. PRACTICAL APPLICATION: The fermented flours present improved nutritional characteristics due to the fermentation process, such as higher antioxidant activity and protein levels. Regarding the population growth and societal demand for healthier food, one possibility is to provide a fermented flour with added nutritional value and raise knowledge about the arrowroot. Thus, these flours can be used in various food items or as an ingredient in food preparations for consumers that desire a healthy diet.

Comprehensive profiling of phenolic compounds by HPLC-DAD-ESI-QTOF-MS/MS to reveal their location and form of presence in different sorghum grain genotypes

In this study, comprehensive profiling of the phenolic compounds in sorghum grain was achieved by analysing the free and bound extracts of sorghum bran and kernel fractions from five Australian sorghum genotypes (1 white, 2 red, 1 brown and 1 black coloured), using HPLC-DAD-ESI-QTOF-MS/MS. A total of 110 phenolic compounds were annotated, out of which 56 were reported for the first time in sorghum grain. Compounds with matched authentic standards were quantified/semi-quantified. Multiple factor analysis (MFA) was performed and heatmaps generated, which provided direct visualisation of the distribution of individual phenolic compounds/subclasses between the sorghum samples. The results indicated that phenolic compounds were concentrated on the bran, and free and bound extracts had different phenolic composition. The phenolic compound/subclass profile varied greatly among sorghum genotypes. Brown sorghum genotype (IS131C) had the highest concentration of total phenolic contents, and the bran fraction of brown sorghum had the most abundant and diverse phenolic composition among all tested samples. This study provides the most comprehensive phenolic profile of Australian representative sorghum grains up to date.

Enzyme-assisted extraction of bioactive non-extractable polyphenols from sweet cherry (Prunus avium L.) pomace

Sweet cherries processing produces big amounts of wastes mainly constituted by cherry pomace that can be a source of bioactive polyphenols. However, during the extraction process, an important fraction called non-extractable polyphenols (NEPs) remains retained in the extraction residue. This work describes the development of an enzyme-assisted extraction (EAE) method to obtain NEPs from sweet cherry pomace employing three different enzymes. Box-Behnken experimental designs were employed to select the optimal conditions of extraction time, temperature, enzyme concentration, and pH. The total phenolic and proanthocyanidin contents and the antioxidant and antihypertensive capacities were measured. Optimal EAE conditions extracted higher content of proanthocyanidins and with higher bioactivity from extraction residue than alkaline and acid hydrolysis. Moreover, there were higher amounts of bioactive phenolics in the extraction residue than in the sweet cherry pomace extract. The estimation of NEPs molecular weight distribution by HPLC-SEC demonstrated that EAE extracted NEPs with high molecular weight.

Total phenolics, flavonoids and antioxidant activity following simulated gastro-intestinal digestion and dialysis of banana (Musa acuminata, AAB) as affected by induced ripening agents

The present study was conducted to evaluate effect of ethephon and acetylene treatments on phenolics, flavonoids and antioxidant activity of banana flesh and their bioaccessibility. Total phenolics, flavonoids and antioxidant activity (DPPH, ABTS, FRAP) were measured at different phases of simulated gastrointestinal digestion of banana treated with 1000 ppm ethephon and 1000 ppm acetylene against natural ripening. The results revealed that inducing ripening lowers the content of phenolics, flavonoids and antioxidant activity considerably in the fresh fruit. Bioavailability of phenolics, flavonoids and FRAP activity were increased significantly (p < 0.05) after gastric digestion regardless of the treatment. The release of polyphenols and flavonoids during gastric digestion in treated banana was more significant than in naturally ripened banana. Recovery of polyphenols after dialysis was significantly high in naturally ripened banana. Dialyzable flavonoids, DPPH and ABTS activities of dialyzed fractions were not significantly affected by ethephon or acetylene treatments.

Low Phytate Peas (Pisum sativum L.) Improve Iron Status, Gut Microbiome, and Brush Border Membrane Functionality In Vivo (Gallus gallus)

The inclusion of pulses in traditional wheat-based food products is increasing as the food industry and consumers are recognizing the nutritional benefits due to the high protein, antioxidant activity, and good source of dietary fiber of pulses. Iron deficiency is a significant global health challenge, affecting approximately 30% of the world's population. Dietary iron deficiency is the foremost cause of anemia, a condition that harms cognitive development and increases maternal and infant mortality. This study intended to demonstrate the potential efficacy of low-phytate biofortified pea varieties on dietary iron (Fe) bioavailability, as well as on intestinal microbiome, energetic status, and brush border membrane (BBM) functionality in vivo (Gallus gallus). We hypothesized that the low-phytate biofortified peas would significantly improve Fe bioavailability, BBM functionality, and the prevalence of beneficial bacterial populations. A six-week efficacy feeding (n = 12) was conducted to compare four low-phytate biofortified pea diets with control pea diet (CDC Bronco), as well as a no-pea diet. During the feeding trial, hemoglobin (Hb), body-Hb Fe, feed intake, and body weight were monitored. Upon the completion of the study, hepatic Fe and ferritin, pectoral glycogen, duodenal gene expression, and cecum bacterial population analyses were conducted. The results indicated that certain low-phytate pea varieties provided greater Fe bioavailability and moderately improved Fe status, while they also had significant effects on gut microbiota and duodenal brush border membrane functionality. Our findings provide further evidence that the low-phytate pea varieties appear to improve Fe physiological status and gut microbiota in vivo, and they highlight the likelihood that this strategy can further improve the efficacy and safety of the crop biofortification and mineral bioavailability approach.

Secondary Bioactive Metabolites from Plant-Derived Food Byproducts through Ecopharmacognostic Approaches: A Bound Phenolic Case Study

The climate emergency and the risks to biodiversity that the planet is facing nowadays, have made the management of food resources increasingly complex but potentially interesting. According to FAO, one-third of the edible parts of food produced throughout the whole food supply chain gets lost or wasted globally every year. At the same time, demographic growth makes it necessary to change course toward sustainable economic development in order to satisfy market demands. The European Union supported the idea of a Circular Economy from 2015 and arranged annual Action Plans toward a greener, climate-neutral economy. Following the biorefinery concept, food waste becomes byproducts that can be recovered and exploited as high added-value materials for industrial applications. The use of sustainable extraction processes to manage food byproducts is a task that research has to support through the development of low environmental impact strategies. This review, therefore, aims to take stock of the possibilities of extracting molecules from food waste biomass following ecopharmacognostic approaches inspired by green chemistry guidelines. In particular, the use of innovative hybrid techniques to maximize yields and minimize the environmental impact of processes is reviewed, with a focus on bound phenolic extractions.

Antioxidant Activity of Lactobacillus plantarum DY-1 Fermented Wheat Germ Extract and Its Influence on Lipid Oxidation and Texture Properties of Emulsified Sausages

The nutrient compositions and in vitro antioxidant activities of water-soluble extract from Lactobacillus plantarum DY-1 fermented wheat germ and its effect on the lipid oxidation and texture properties of emulsified sausages were investigated. The optimal hydroxyl radical scavenging capacity of 72.8 ± 2.9% was demonstrated for fermented wheat germ extract (FWGE) by terms of the fermentation conditions as follows: fermentation time of 26 h, fermentation temperature of 35°C, initial pH of 3.0, solid to liquid ratio of 1/10, and inoculum amount of 0.48 g. The enhancement in FWGE content could improve the oxidation stability of emulsified sausages by retarding the formation of thiobarbituric acid-reactive substances (TBARSs) during 7 days of storage at 4°C. However, a higher FWGE content (2.14%) resulted in 78% of increase in cooking loss (p<0.05) and 41.4% of decrease in hardness (p<0.05) of emulsified sausages. It was suggested that the biotransformation of wheat germ with lactic acid bacteria could improve its nutritional quality and functional properties.

Antimicrobial, antioxidant, volatile and phenolic profiles of cabbage-stalk and pineapple-crown flour revealed by GC-MS and UPLC-MSE

Unconventional parts of vegetables represent a rich source of health-promoting phytochemicals. The phenolic profile of cabbage-stalk flour (CSF), pineapple-crown flour (PCF), and their essential oils were characterized via UPLC-ESI-QTOF-MS^E and GC-FID/MS. Antimicrobial activity was tested against five strains, and antioxidant activities were determined in free and bound extracts. Globally, 177 phenolics were tentatively identified in PCF (major p-coumaric acid, ferulic acid, and 4-hydroxybenzaldehyde) and 56 in CSF (major chlorogenicacid, quercetin 3-O-glucuronide, and p-coumaric acid). PCF exhibited a distinguished profile (lignans, stilbenes) and antioxidant capacity, especially in bound extracts (1.3 g GAE.100 g^-1; 0.6 g catechin eq.100 g^-1; DPPH: 244.7; ABTS: 467.8; FRAP: 762.6 µg TE.g^-1, ORAC: 40.9 mg TE.g^-1). The main classes of volatile compounds were fatty acids, their esters, and terpenes in CSF (30) and PCF (41). A comprehensive metabolomic approach revealed CSF and PCF as a promising source of PC, showing great antioxidant and discrete antimicrobial activities.

Preparation and α-Glucosidase Inhibitory Activity of Gallic Acid-Dextran Conjugate

Phenolic acid-polysaccharide conjugates, produced in plant food and medicine processing, are thought to account for the α-glucosidase inhibitory activity of the final products. However, this speculation lacks experimental support because of the complexity of the plant system and the polysaccharide structure. In this study, with dextran (average molecular weight, 1000) as the skeleton, a gallic acid-dextran conjugate was synthesized and confirmed by ultraviolet, infrared, and nuclear magnetic resonance spectroscopic analysis for the first time. Furthermore, this gallic acid-dextran conjugate showed inhibition of α-glucosidase due to galloyl groups in a mixed competitive and noncompetitive inhibition mode, whose performance was superior to that of acarbose.

The outer influences the inner: Postharvest UV-B irradiation modulates peach flesh metabolome although shielded by the skin

UV-B-driven modulation of secondary metabolism in peach fruit by enhancing the biosynthesis of specific phenolic subclasses, is attracting interest among consumers. However, current literature explored the UV-B-induced metabolic changes only in peach skin subjected to direct UV-B irradiation. Accordingly, this study aimed to understand whether UV-B radiation penetrates the fruit skin and is able to induce metabolic changes also within the inner flesh. Peaches were UV-B-irradiated either 10 or 60 min, and the flesh was sampled after 24 and 36 h. Non-targeted metabolomics revealed that UV-B has a strong impact on peach flesh metabolome, determining an initial decrease after 24 h, followed by an overall increase after 36 h, particularly for terpenoids, phenylpropanoids, phytoalexins and fatty acids in the 60 min UV-B-treated samples (+150.02, +99.14, +43.79 and +25.44 log₂FC, respectively). Transmittance analysis indicated that UV-B radiation does not penetrate below the skin, suggesting a possible signalling pathway between tissues.

Non-Extractable Polyphenols from Food By-Products: Current Knowledge on Recovery, Characterisation, and Potential Applications

Non-extractable polyphenols (NEPs), or bound polyphenols, are a significant fraction of polyphenols that are retained in the extraction residues after conventional aqueous organic solvent extraction. They include both high molecular weight polymeric polyphenols and low molecular weight phenolics attached to macromolecules. Current knowledge proved that these bioactive compounds possess high antioxidant, antidiabetic, and other biological activities. Plant-based food by-products, such as peels, pomace, and seeds, possess high amount of NEPs. The recovery of these valuable compounds is considered an effective way to recycle food by-products and mitigate pollution, bad manufacturing practice, and economic loss caused by the residues management. The current challenge to valorise NEPs from plant-based by-products is to increase the extraction efficiency with proper techniques, choose appropriate characterising methods, and explore potential functions to use in some products. Based on this scenario, the present review aims to summarise the extraction procedure and technologies applied to recover NEPs from plant-based by-products. Furthermore, it also describes the main techniques used for the characterisation of NEPs and outlines their potential food, pharmaceutical, nutraceutical, and cosmetic applications.

The Application of Metabolomics for the Study of Cereal Corn (Zea mays L.)

Corn (Zea mays L.) is an important cereal crop indigenous to the Americas, where its genetic biodiversity is still preserved, especially among native populations from Mesoamerica and South America. The use of metabolomics in corn has mainly focused on understanding the potential differences of corn metabolomes under different biotic and abiotic stresses or to evaluate the influence of genetic and environmental factors. The increase of diet-linked non-communicable diseases has increased the interest to optimize the content of bioactive secondary metabolites in current corn breeding programs to produce novel functional foods. This review provides perspectives on the role of metabolomics in the characterization of health-relevant metabolites in corn biodiversity and emphasizes the integration of metabolomics in breeding strategies targeting the enrichment of phenolic bioactive metabolites such as anthocyanins in corn kernels.

Potential of grape byproducts as functional ingredients in baked goods and pasta

Wine making industry generates high quantities of valuable byproducts that can be used to enhance foods in order to diminish the environmental impact and to obtain more economic benefits. Grape byproducts are rich in phenolic compounds and dietary fiber, which make them suitable to improve the nutritional value of bakery, pastry, and pasta products. The viscoelastic behavior of dough and the textural and the sensory characteristics of baked goods and pasta containing grape byproducts depend on the addition level and particle size. Thus, an optimal dose of a finer grape byproducts flour must be found in order to minimize the negative effects such as low loaf volume and undesirable sensory and textural characteristics they may have on the final product quality. In the same time, an enrichment of the nutritional and functional value of the product by increasing the fiber and antioxidant compounds contents is desired. The aim of this review was to summarize the effects of the chemical components of grape byproducts on the nutritional, functional, rheological, textural, physical, and sensory characteristics of the baked goods and pasta. Further researches about the impact of foods enriched with grape byproducts on the human health, about molecular interactions between components, and about the effects of grape pomace compounds on the shelf life of baked goods and pasta are recommended.

New Advances in the Determination of Free and Bound Phenolic Compounds of Banana Passion Fruit Pulp (Passiflora tripartita, var. Mollissima (Kunth) L.H. Bailey) and Their In Vitro Antioxidant and Hypoglycemic Capacities

Banana passion fruit (Passiflora tripartite L.H. Bailey) is a lesser known species of the genus Passiflora. This fruit typically grows in the Andean region of Ecuador and it is locally known as tumbo, taxo or curuba. The juice of this fruit is highly appreciated in South America. Extracts of banana passion fruit were characterized for their content levels of free and bound phenolic compounds by high performance liquid chromatography coupled to high resolution mass spectrometry detector (HPLC-ESI-TOF-MS). A total of 82 polar compounds classified as phenolic acid derivatives, organic acids, benzophenones, flavan-3-ols, flavonols and flavones were detected in the extracts. The total phenolic content was 2356 mg 100 g^-1 dry matter, with the bound phenolic fraction representing 37.7% of total amounts. Flavan-3-ols, such as (epi)catechin, (epi)azfelechin and their derivatives, were the main phenolic compounds in the free phenolic fraction; however, phenolic acids represented the most abundant class of bound phenolic extracts. The antioxidant and hypoglycemic capacities reported for banana passion fruit were higher than for other fruits. To our knowledge, this is the first time that bound phenolic compounds have been described in banana passion fruit pulp.

Bioaccessibility and gut metabolism of phenolic compounds of breads added with green coffee infusion and enzymatically bioprocessed

This study aimed at investigating two strategies to enhance the bioaccessibility of phenolic compounds from whole-wheat breads: enzymatic bioprocessing and addition of green coffee infusion. Although both strategies had a significant effect on increasing the contents of total soluble phenolic compounds in breads, the addition of green coffee infusion was much more relevant (19.1-fold) than enzymatic bioprocessing (1.8-fold). The phenolic compounds present as soluble forms were completely released from all breads' matrix already at the oral phase of digestion. While gastric digestion did not promote the release of insoluble phenolic compounds, intestinal conditions led to a slight release. All bread samples showed maximum phenolic compounds bioaccessibility after 4 h of gut fermentation. Upon the end of in vitro digestion and gut fermentation, the difference between the strategies was that enzymatic bioprocessing accelerated ferulic acid release, while the addition of green coffee infusion increased 10.4-fold the overall phenolic compounds bioaccessibility.

Feruloylated oligosaccharides and ferulic acid alter gut microbiome to alleviate diabetic syndrome

Gut microbiome has been proven to be involved in the development of type 2 diabetes (T2D). Additionally, increasing evidence showed that the composition of gut microbiome is highly associated with the outcome of T2D therapy. Previously we demonstrated that feruloylated oligosaccharides (FOs) and ferulic acid (FA) alleviated diabetic syndrome in rats, but the detailed mechanism has not been explored yet. In this study we strived to characterize how FOs and FA altered the gut microbiome and related metabolome in diabetic rats by using high-throughput sequencing of 16S rRNA and gas chromatography (GC). Our results showed that FOs reduced the abundance of Lactobacillus, Ruminococcus, Oscillibacter, and Desulfovibrio, but increased the abundance of Akkermansia, Phascolarctobacterium and Turicibacter. The structure of gut microbiome in FOs treated rats was similar with healthy rats rather than diabetic rats. Likewise, FA decreased the portion of Lactobacillus, Ruminococcus, but promoted the growth of Bacteroides, Blautia, Faecalibacterium, Parabacteroides and Phascolarctobacterium. Additionally, the short-chain fatty acids (SCFAs) and branched-chain fatty acids (BCFAs), the main bacterial lipid metabolites in gut mediating host glucose metabolism, was dramatically elevated along with FOs and FA treatment. Our findings indicated that FOs and FA attenuated diabetic syndrome in rats most likely by modulating the composition and metabolism of gut microbiome. The study gives new insight into the mechanism underlying the anti-diabetes effect of functional foods as well as facilitates the development of dietary supplements for diabetic patients.

Biliaderis C. Fermented Cereal-based Products: Nutritional Aspects, Possible Impact on Gut Microbiota and Health Implications

Fermentation, as a process to increase the security of food supply, represents an integral part of food culture development worldwide. Nowadays, in the evolving functional food era where new sophisticated technological tools are leading to significant transformations in the field of nutritional sciences and science-driven approaches for new product design, fermentation technology is brought to the forefront again since it provides a solid foundation for the development of safe food products with unique nutritional and functional attributes. Therefore, the objective of the present review is to summarize the most recent advances in the field of fermentation processes related to cereal-based products. More specifically, this paper addresses issues that are relevant to nutritional and health aspects, including their interrelation with intestinal (gut) microbiome diversity and function, although clinical trials and/or in vitro studies testing for cereal-based fermented products are still scarce.

Phytochemical Compounds and Antioxidant Activity Modified by Germination and Hydrolysis in Mexican Amaranth

Amaranth (Amaranthus spp.) grains have become essential for human health and nutrition; due to the presence of bioactive compounds that have shown some biological activities. This study aimed to evaluate the effect of germination, enzymatic hydrolysis, and its combination on the phytochemical compounds and antioxidant activity in Mexican amaranth. Germinated amaranth flours (GAF) exhibited increases in the concentrations of soluble protein (SP), total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC) and antioxidant activity (AOX) by 35.7, 17.2, 163.0, 1472.2, and 54.3%, respectively, compared with ungerminated amaranth flours (UAF). In SDS-PAGE, both hydrolysates of UAF and GAF exhibited low molecular weight bands (< 10 kDa). The hydrolysates of UAFH and GAFH had the highest degree of hydrolysis at 205 min of sequential hydrolysis (pepsin with pancreatin) time with 73.4 and 60.3%, respectively. Both hydrolysates obtained from GAF and UAF released significantly SP, TPC, TFC after sequential enzymatic hydrolysis (up 205 min), which led to a remarkable improvement of AOX when compared to nonhydrolyzed amaranth samples. The UAFH and GAFH had the best AOX at 270 min of enzymatic hydrolysis with 983.1 and 1304.9 μmol TE/mg SP, respectively. Hence, the combination of germination and enzymatic hydrolysis could be used to produce functional ingredients for food product development.

Effect of Extrusion Processing Conditions on the Phenolic Compound Content and Antioxidant Capacity of Sorghum (Sorghum bicolor (L.) Moench) Bran

Sorghum is a cereal with little use in human diet; however, this grain can provide several nutrients and, additionally, has a high content of phenolic compounds concentrated in bran, which could be beneficial to human health due to its high antioxidant capacity. However, these bioactive compounds are bound within the cell wall matrix; it is necessary to release these compounds to take advantage of their antioxidant properties. The extrusion process increases the accessibility of bound phenolic compounds, breaking their bonds from the bran matrix. The aim of this study was to determine the optimal extrusion conditions for maximizing the phenolic compound content and antioxidant capacity of sorghum bran extrudate. The extrusion process factors evaluated were feed moisture (FM) from 25 to 35% and the fourth extrusion zone temperature (T) in the range of 140-180 °C. Analysis of variance and response surface analysis were used in the evaluation. The prediction coefficient, (FM)², (T)² and their interaction (FM)(T) significantly affected the free total phenolic compounds. The antioxidant capacity of the free total phenolic compounds was significantly affected by (FM)² and (T)². The optimal extrusion conditions were FM = 30% and T = 160 °C, which provided free total phenolic compounds with a value of 7428.95 μg GAE/g (predicted value: 7810.90 μg GAE/g) and antioxidant capacity with a value of 14.12 μmol TE/g (predicted value: 14.85 μmol TE/g). Results confirmed that extrusion process optimization was useful to increase the content of phenolic compounds and improved the antioxidant capacity of sorghum bran.

Fluidized-bed drying of black rice grains: Impact on cooking properties, in vitro starch digestibility, and bioaccessibility of phenolic compounds

This study evaluated the influence of different fluidized-bed drying temperatures (20, 60, and 100 °C) on the cooking properties, in vitro starch digestibility, and phenolic bioaccessibility of black rice. The results indicated that the formation of fissures in the grains dried at or above 60 °C reduced the physical integrity of the grains after cooking, increasing the starch digestion and the rehydration ratio, and reduced the cooking time, the hardness and adhesiveness. Due to the higher digestibility of grains dried at higher temperatures, an increase in the bioaccessibility of ferulic acid, which was previously associated with the polysaccharides, was observed. Caffeic acid was the only phenolic compound whose levels decreased when the drying temperature increased. At high temperatures and in the gastric phase, cyanidin chalcones were formed due to the deglycosylation of cyanidin-3-O-glucoside. PRACTICAL APPLICATION: The results of this study provide information to the food industry about the effects of different fluidized-bed drying temperatures on the rice structure after cooking and that, consequently, affect the availability of bioactive compounds after digestion and the glycemic index of black rice.

Effect of Moringa oleifera L. Leaf Powder Addition on the Phenolic Bioaccessibility and on In Vitro Starch Digestibility of Durum Wheat Fresh Pasta

Fresh pasta was formulated by replacing wheat semolina with 0, 5, 10, and 15 g/100 g (w/w) of Moringa oleifera L. leaf powder (MOLP). The samples (i.e., M0, M5, M10, and M15 as a function of the substitution level) were cooked by boiling. The changes in the phenolic bioaccessibility and the in vitro starch digestibility were considered. On the cooked-to-optimum samples, by means of ultra-high-performance liquid chromatography-quadrupole time-of-flight (UHPLC-QTOF) mass spectrometry, 152 polyphenols were putatively annotated with the greatest content recorded for M15 pasta, being 2.19 mg/g dry matter (p < 0.05). Multivariate statistics showed that stigmastanol ferulate (VIP score = 1.22) followed by isomeric forms of kaempferol (VIP scores = 1.19) and other phenolic acids (i.e., schottenol/sitosterol ferulate and 24-methylcholestanol ferulate) were the most affected compounds through the in vitro static digestion process. The inclusion of different levels of MOLP in the recipe increased the slowly digestible starch fractions and decreased the rapidly digestible starch fractions and the starch hydrolysis index of the cooked-to-optimum samples. The present results showed that MOLP could be considered a promising ingredient in fresh pasta formulation.

Effects of steam explosion pretreatment on the composition and biological activities of tartary buckwheat bran phenolics

Steam explosion (SE) is an efficient technology to disrupt materials for improving their quality. In this study, SE was applied to release phenolics and improve the roughening of tartary buckwheat bran. The results showed that SE promoted the dissolution of phenolics, particularly, the content of the bound fraction was nearly increased by two times (0.36 vs. 0.99 mg GAE per g DW). The analysis of the phenolic composition showed that SE improved the liberation of bound pyrogallic acid, protocatechuic acid and caffeic acid. The biological activity tests indicated that SE effectively enhanced the oxygen radical absorbance capacity (ORAC) in vitro of the extract of bound phenolics by 270%. It also improved the cellular antioxidant activity (CAA) in vitro of the extract of free phenolics by 215%. Furthermore, SE showed potential in improving the antiproliferative activity of the total phenolic extract against Caco-2 cells as well as the bound phenolic extract against HepG2 cells in vitro.