Effect of freeze-drying and oven-drying on volatiles and phenolics composition of grape skin

Insights into the key odorants in fresh and dried Amomum tsaoko using the sensomics approach

To identify the key odorants in Amomum tsaoko (AT), volatiles in fresh AT (FAT) and dried AT (DAT) were investigated using molecular sensory science. In addition to this, the sensomics approach was used to confirm the presence of the compound in FAT that contributed the most to its aroma profile. A total of 49 odor-active compounds (43 in FAT and 42 in DAT) with flavor dilution (FD) factors ranging from 1 to 6561 were identified, with eucalyptol exhibiting the highest FD factor of 6561. Odorants with FD factors ≥ 27 were quantitated, and 23 and 20 compounds in FAT and DAT, respectively, with odor activity value ≥ 1 were determined as key odorants. Recombination and omission experiment further indicated that (E)-2-dodecenal, geranial, octanal, (E)-2-octenal, (E)-2-decenal, and eucalyptol contributed significantly to the overall aroma profile of FAT. After drying of FAT, the concentrations of aldehydes decreased significantly, whereas those of terpene hydrocarbons increased. Multivariate statistical analysis revealed that 26 FAT and 23 DAT odorants were biomarker compounds.

Rosmarinic Acid and Flavonoids of the Seagrass Zostera noltei: New Aspects on Their Quantification and Their Correlation with Sunlight Exposure

Seagrasses are plants adapted to the marine environment that inhabit shallow coastal waters, where they may be exposed to direct sunlight during low tides. These plants have photoprotection mechanisms, which could include the use of phenolic secondary metabolites. In this study, rosmarinic acid (RA) and the flavonoids of Zostera noltei from the Bay of Cadiz (Spain) have been analyzed, first to define suitable conditions of leaves (i.e., fresh, dried, or frozen) for quantitative analysis, and then to explore the potential correlation between the phenolic profile of the leaves and sunlight exposure using an in situ experimental approach. Compared with fresh leaves, the contents of RA and flavonoids were significantly lower in air-dried and freeze-dried leaves. Freezing caused highly variable effects on RA and did not affect to flavonoid levels. On the other hand, the content of RA was significantly higher in plants that emerged during low tides than in plants permanently submerged, while plants underneath an artificial UV filter experienced a progressive reduction in RA content. However, the major flavonoids did not show a clear response to sunlight exposure and were unresponsive to diminished UV incidence. The results showed a positive correlation of RA with direct sunlight and UV exposure of leaves, suggesting that this compound contributes to the photoprotection of Z. noltei.

Improvement of textural and sensory characteristics of aged rice using hydrothermal treatment with xanthan gum

Aged rice (AR) was mildly heated in aqueous dispersions containing different amounts of xanthan gum (Xan) at 60 °C for 1 h, and then dried in a humidity chamber (50 °C, 80% RH) for 12 h. The AR kernels treated without Xan showed a coarse surface with many pores after cooking, whereas the same rice treated with Xan showed a smooth and uniform surface. Prior to the treatment, the cooked AR was harder and less sticky than the cooked fresh rice (FR). The hydrothermal treatment softened the cooked AR although did not change its adhesiveness. The same treatment in the presence of Xan could increase the adhesiveness of AR, making the textural characteristics of AR similar to those of FR. Sensory evaluation revealed that the mild heat treatment in the presence of Xan restored the eating quality and acceptability of cooked AR which had been lost by aging.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01306-0.

Stability of polyphenols in food processing

In recent years, polyphenols have attracted considerable attention due to their diverse potential health-beneficial effects on humans. Polyphenols are widely distributed in natural plants, and therefore play an important role in human food. Thermal processing, irradiation, fermentation, high pressure, microwave, and drying are several popular food processing methods. However, polyphenols are instable in food processing, which easily degrade and react with other components because of their polyhydroxy characteristic. Traditional and advanced technologies have been used to characterize the stability of polyphenols. The main influence factors of stability of polyphenols such as pH, temperature, light, oxygen, enzymes, metal ions, as well as macromolecules, are summarized. Besides, thermal processing greatly promoted the degradation of polyphenols. Thermal degradation mechanisms and products of some polyphenols, such as quercetin and rutin, have been intensively demonstrated. Nevertheless, the structural changes of polyphenols caused by food processing, may lead to different bioactivities from the obtained results based on unprocessed polyphenols. Therefore, to maximize the beneficial effects of polyphenols ingested by human from processed food, the stability of polyphenols in food processing must be thoroughly investigated to assess their real bioactivities. In addition, some available technologies for improving the stability of polyphenols in food processing have been proposed.

Construction of Genetic Linkage Map and Mapping QTL Specific to Leaf Anthocyanin Colouration in Mapping Population 'Allahabad Safeda' × 'Purple Guava (Local)' of Guava (Psidium guajava L.)

In the present investigation, F1 hybrids were developed in guava (Psidium guajava L.) by crossing high leaf-anthocyanin reflective-index (ARI1) content cultivars purple guava (local) 'PG', 'CISH G-1' and low leaf-ARI1 content cultivar Seedless 'SL' with Allahabad Safeda 'AS'. On the basis of phenotypic observations, high ARI1 content was observed in the cross 'AS' × 'PG' (0.214). Further, an SSR-markers-based genetic linkage map was developed from a mapping population of 238 F1 individuals derived from cross 'AS' × 'PG'. The linkage map comprised 11 linkage groups (LGs), spanning 1601.7 cM with an average marker interval distance of 29.61 cM between adjacent markers. Five anthocyanin-content related gene-specific markers from apple were tested for parental polymorphism in the genotypes 'AS' and 'PG'. Subsequently, a marker, viz., 'MdMYB10F1', revealed a strong association with leaf anthocyanin content in the guava mapping population. QTL (qARI-6-1) on LG6 explains much of the variation (PVE = 11.51% with LOD = 4.67) in levels of leaf anthocyanin colouration. This is the first report of amplification/utilization of apple anthocyanin-related genes in guava. The genotypic data generated from the genetic map can be further exploited in future for the enrichment of linkage maps and for identification of complex quantitative trait loci (QTLs) governing economically important fruit quality traits in guava.

Analisis Senyawa Aktif Trigeminal Andaliman dengan Variasi Metode Pengeringan dengan Pendekatan GC-MS

Sanshool compounds are the trigeminal active compounds in andaliman (Zanthoxylum acantho-podium DC) with a numbing and tingling sensation. The analysis of such compounds is usually done through HPLC approach; however, limited studies have reported that the analysis of such compounds could be conducted with Gas Chromatography-Mass Spectrometry (GC-MS). This method could save research time and funding by analyzing both sanshools and volatiles simultaneously, which would describe the complete profile of andaliman flavor compounds. This study aimed to confirm the potency of GC-MS in analyzing sanshool compounds and to utilize this method in studying the impact of different drying methods towards andaliman trigeminal active compounds. Andaliman was dried with five drying methods (sun, sunshade, air, oven, and freeze-drying) and was macerated with chloroform, concentrated, and analyzed with GC-MS. The results of this study showed that GC-MS was able to analyze sanshool compounds efficiently. Drying had no statistically significant impact on sanshool quantities extracted from andaliman. Fresh andaliman contained 0.69 % (dry weight basis) of α-sanshool, the main sanshool in andaliman. On the other hand, dried andaliman contained 0.80-1.08% of α-sanshool (dry weight basis). As oven drying managed to produce andaliman with a similar concentration of α-sanshool at a faster time and more affordable cost than other drying methods, oven drying was suggested as the ideal drying method to extend the shelf life of andaliman.

Advances in drying techniques for retention of antioxidants in agro produces

Antioxidants are compounds that are essential for the human body which prevents cell from disease causing free radicals. Antioxidants are present in a wide range of fruits, vegetables, and spices. However, a considerable amount of antioxidants is lost during the post-harvest drying operation of agro produces for their shelf-life enhancement. Hence, retention of antioxidants becomes utmost importance in preserving the nutritional aspects of fruits and vegetables. Compared to conventional hot air drying, methods like freeze drying, vacuum drying, and dehumidified drying helps in the retention of antioxidants. However, the drawbacks prevalent in current drying practices, such as high-power consumption and high capital cost, could be eliminated by adopting novel drying mechanisms. This review focuses on various pretreatment methods like ultra-sonication, high pressure processing, pulsed electric field and ethanol treatment prior to drying operation helps in enhancing the drying efficiency with maximum retention of antioxidants. In addition, hybrid drying technologies such as microwave assisted drying, IR-radiated drying and electro-magnetic assisted drying methods also could significantly improve the retention of antioxidants.HIGHLIGHTSDrying is the most commonly adopted unit operation for enhancing the shelf life of perishable agro produces.However, drying is accompanied by loss of bioactive, color, texture, and sensory attributes.Compared to conventional drying techniques like hot air drying, methods like freeze drying, vacuum drying and dehumidified drying helps in the retention of antioxidants present in agro/food produces.Pretreatment methods like Ozonation, ultra-sonication, and UV radiation prior to drying are also found to improve the drying performance with good retention of antioxidants.Recent developments like microwave-assisted and IR-assisted drying methods perform well in the retention of antioxidants with less energy consumption.

Impact of drying methods on natural antioxidants, phenols and flavanones of immature dropped Citrus sinensis L. Osbeck fruits

Citrus fruits are famous for nutritional value and studies are there for extraction of secondary metabolites from citrus waste. An attempt was made to quantify antioxidants, flavonoids and phenols from dropped fruits of 8–24 mm size, to find the impact of freeze and hot-air oven drying techniques on extraction. Flavonoids (hesperidin, narirutin/isonaringin, diosmin and didymin/neoponcirin) were quantified through high performance liquid chromatography (HPLC) and total phenols (TPC) were estimated by Folin-Ciocalteu method. Antioxidant capacity was adjudged by azino-bis [3-ethylbenzthiazoline-6-sulfonic acid] (ABTS), 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric Reducing Antioxidant Power (FRAP). Freeze dried fruits of 10 mm and 12 mm retained maximum hesperidin content (22.383% and 21.560%) in comparison to hot-air oven counterparts (18.377% and 15.090%). Narirutin/isonaringin (1.343% and 1.191%), diosmin (5.293% and 3.234%) and didymin/neoponcirin (1.187% and 1.113%) content were found higher in 8 mm and 10 mm freeze dried fruits. The antioxidant capacity (7.548–11.643 mmol L⁻¹ Trolox, 8.164–14.710 mmol L⁻¹ Trolox, 4.008–5.863 mmol L⁻¹ Trolox by ABTS, DPPH and FRAP assays) and TPC were found higher in freeze dried samples. Significant correlation was found between antioxidant capacity, TPC and flavonoids at p < 0.01. Freeze drying technique can be adopted for retaining and quality extraction of bioactive compounds from immature dropped fruits for further use in nutraceutical industries.

Effects of ultrasound, heat, ascorbic acid and CaCl2 treatments on color enhancement and flavor changes of freeze-dried carrots during the storage period

Discoloration and unpleasant flavor were observed in freeze-dried carrots (FDC) during shelf life. This study aimed to investigate the effects of thermal/non-thermal pre-treatments and storage temperatures on the color and flavor of FDC during the 120-day storage. Results showed that terpenes and sulfur-containing organics were the main volatiles sensitive to the 60 °C treatment (p < 0.05). Nonenzymatic browning of FDC happened during storage, which was significantly positively related to moisture content (r = 0.63) and water activity (r = 0.84), while negatively correlated with total carotenoid content (TCC, r = -0.62). However, redness (29.66%), chroma (16.59%) and TCC (3.40%) of FDC at 120-day (25 °C) was effectively improved after the combination treatment of ultrasound (40 kHz, 100 W, 10 min) and ascorbic acid (2%, w/v)-CaCl₂ (1%, w/v) solution (UAA-CaCl₂), showing that carrots pre-treated with UAA-CaCl₂ and preserved at 25 °C facilitated the FDC storage.

Incorporation of phenolic-rich ingredients from integral valorization of Isabel grape improves the nutritional, functional and sensory characteristics of probiotic goat milk yogurt

This study elaborated different probiotic goat milk yogurt formulations with addition of a low-calorie Isabel "Precoce" grape preparation and flour from derived solid by-products. Physicochemical characteristics, probiotic counts, phenolic and protein/peptide molecular weight profile, antioxidant capacity (AC) and sensory acceptance of different yogurt formulations were evaluated. Yogurts with Isabel grape ingredients (IGI) had high nutritional value, distinct phenolic profile and high AC. High counts of probiotic Lactobacillus acidophilus La-05 were found in yogurts during storage. AC of yogurts with IGI increased during a simulated gastrointestinal digestion with breakdown of high molecular weight proteins and release of protein-bound phenolics. AC of yogurts with IGI should be linked to goat milk peptides and Isabel grape phenolics. Yogurts with IGI had enhanced sensory acceptance. Incorporation of Isabel grape preparation and derived by-product flour into probiotic goat milk yogurt resulted in an added-value product with multifunctional characteristics and improved sensory characteristics.

Effects of High Hydrostatic Pressure Combined with Vacuum-Freeze Drying on the Aroma-Active Compounds in Blended Pumpkin, Mango, and Jujube Juice

A combination process of completely non-thermal processing methods involving high hydrostatic pressure (HHP) and vacuum-freeze drying (VFD) for producing a new snack from fruit and vegetable blends was developed, and the effect of the process on flavor quality was investigated. The HHP-VFD treatment did not significantly reduce volatile compound contents compared to single HHP or VFD. Gas chromatography-olfactometry showed that HHP-VFD raised the contents of floral-like volatile compounds (e.g., β-ionone) compared to the untreated sample. Sensory evaluation analysis confirmed that the overall liking was unchanged after the HHP-VFD treatment. The HHP-VFD combined treatment is effective in maintaining the flavor and extending shelf life, and is convenient for the portability and transportation of ready-to-drink juice.

Pressurized Extraction as an Opportunity to Recover Antioxidants from Orange Peels: Heat treatment and Nanoemulsion Design for Modulating Oxidative Stress

Orange peel by-products generated in the food industry are an important source of value-added compounds that can be potentially reused. In the current research, the effect of oven-drying (50–70 °C) and freeze-drying on the bioactive compounds and antioxidant potential from Navelina, Salustriana, and Sanguina peel waste was investigated using pressurized extraction (ASE). Sixty volatile components were identified by ASE-GC-MS. The levels of terpene derivatives (sesquitenenes, alcohols, aldehydes, hydrocarbons, and esters) remained practically unaffected among fresh and freeze-dried orange peels, whereas drying at 70 °C caused significative decreases in Navelina, Salustriana, and Sanguina peels. Hesperidin and narirutin were the main flavonoids quantified by HPLC-MS. Freeze-dried Sanguina peels showed the highest levels of total-polyphenols (113.3 mg GAE·g⁻¹), total flavonoids (39.0 mg QE·g⁻¹), outstanding values of hesperedin (187.6 µg·g⁻¹), phenol acids (16.54 mg·g⁻¹ DW), and the greatest antioxidant values (DPPH•, FRAP, and ABTS^•+ assays) in comparison with oven-dried samples and the other varieties. Nanotechnology approaches allowed the formulation of antioxidant-loaded nanoemulsions, stabilized with lecithin, starting from orange peel extracts. Those provided 70–80% of protection against oxidative UV-radiation, also decreasing the ROS levels into the Caco-2 cells. Overall, pressurized extracts from freeze-drying orange peel can be considered a good source of natural antioxidants that could be exploited in food applications for the development of new products of commercial interest.

Chemosensory approach supported-analysis of wintering radishes produced in Jeju island by different processing methods

The purpose of this study was to investigate sensory characteristics in radishes, processed through different methods, using chemosensory-assisted instruments. For electronic tongue (E-tongue) analysis, freeze-dried radish was high in the sensor values of sourness, umami, and sweetness, however, the saltiness was the lowest. In particular, the sensor values of taste freeze-dried radish have changed more than that of thermally processed radishes. Unlike the results of E-tongue, volatiles of freeze-dried radish have changed less than that of thermally processed radishes. In detail, amounts of sulfur-containing compound (thiophene) in freeze-dried radish were relatively higher than thermally processed radishes by an electronic nose. For gas chromatography-mass spectrometry and GC-olfactometry, the amount of sulfur-containing compounds in freeze-dried radish were also relatively higher than thermally processed radishes, and odor active compounds were also high in freeze-dried radish.

Impact of Drying Processes on the Nutritional Composition, Volatile Profile, Phytochemical Content and Bioactivity of Salicornia ramosissima J. Woods

Salicornia ramosissima J. Woods is a halophyte plant recognized as a promising natural ingredient and will eventually be recognized a salt substitute (NaCl). However, its shelf-life and applicability in several food matrices requires the use of drying processes, which may have an impact on its nutritional and functional value. The objective of this study was to evaluate the effect of oven and freeze-drying processes on the nutritional composition, volatile profile, phytochemical content, and bioactivity of S. ramosissima using several analytical tools (LC-DAD-ESI-MS/MS and SPME-GC-MS) and bioactivity assays (ORAC, HOSC, and ACE inhibition and antiproliferative effect on HT29 cells). Overall, results show that the drying process changes the chemical composition of the plant. When compared to freeze-drying, the oven-drying process had a lower impact on the nutritional composition but the phytochemical content and antioxidant capacity were significantly reduced. Despite this, oven-dried and freeze-dried samples demonstrated similar antiproliferative (17.56 mg/mL and 17.24 mg/mL, respectively) and antihypertensive (24.56 mg/mL and 18.96 mg/mL, respectively) activities. The volatile composition was also affected when comparing fresh and dried plants and between both drying processes: while for the freeze-dried sample, terpenes corresponded to 57% of the total peak area, a decrease to 17% was observed for the oven-dried sample. The oven-dried S. ramosissima was selected to formulate a ketchup and the product formulated with 2.2% (w/w) of the oven-dried plant showed a good consumer acceptance score. These findings support the use of dried S. ramosissima as a promising functional ingredient that can eventually replace the use of salt.

Quantification of Flavonoids, Phenols and Antioxidant Potential from Dropped Citrus reticulata Blanco Fruits Influenced by Drying Techniques

Physiologically dropped immature Citrus reticulata Blanco fruits are regarded as waste and discarded in the citrus orchard but are a good source of bioactive compounds including flavonoids, antioxidants and total phenols. A study was undertaken to identify and quantify these bioactive compounds and to investigate the influence of different drying techniques, namely freeze drying and hot air oven drying, on flavonoids namely flavanone glycosides, antioxidant potential and total phenol content in immature dropped fruits of Citrus reticulata Blanco. Flavonoids were quantified in high-performance liquid chromatography (HPLC). The antioxidant activity were investigated with three assays azino-bis [3-ethylbenzthiazoline-6-sulfonic acid]) (ABTS), 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), Ferric Reducing Ability of Plasma (FRAP) and total phenol content was determined. Freeze dried samples of 12 and 14 mm size retained maximum hesperidin flavonoid content (27.03% and 27.20%) as compared to the hot air dried samples (17.99%) and retained higher phenolic content ranged from 50.54-54.19 mg GAEL^-1. The antioxidant activity in freeze dried fruits was from 12.21-13.55 mM L^-1 Trolox and 15.27-16.72 mM L^-1 Trolox with ABTS, DPPH assay and FRAP values ranging from 7.31-9.07 mM L^-1 Trolox. Significant positive correlation was found between the flavonoid hesperidin with antioxidant assays and total phenolic content (TPC). The results showed that waste citrus fruits can act as potential source of bioflavonoids, especially hesperidin, and antioxidants for pharmaceutical as well as nutraceutical industry.

Changes in volatiles and aroma profile of andaliman (Zanthoxylum acanthopodium DC.) upon various drying techniques

Andaliman is a highly perishable Indonesian spice that could be preserved by drying. As the drying influence on andaliman volatiles and aroma profile has not been reported, this study aimed to determine the impact of five drying processes on them and the critical volatiles correlated with favorable aroma attributes. Limonene, geranial, α-pinene, sabinene, β-myrcene, (E)-2-hexenal tended to decrease while geranyl acetate, citronellal, neral tended to increase upon drying. Limonene, andaliman major volatiles, was lost considerably from 28093 µg/g solids (fresh) to 19299-21857 µg/g solids (dried). Drying significantly altered citrus, orange peel, green, warm, and lime leaf aroma. Citronellal, limonene, (Z)-β-ocimene, (E)-β-ocimene, β-citronellol, sabinene, and geranial, played substantial roles in andaliman sensory acceptability due to significant correlation to the favorable aroma attributes (citrus, orange peel, acidic). Oven drying was proposed as the ideal drying method because of its short duration, low water activity, superior overall liking, and high volatile content.

Effect of Freeze Drying and Simulated Gastrointestinal Digestion on Phenolic Metabolites and Antioxidant Property of the Natal Plum (Carissa macrocarpa)

Natal plums (Carissa macrocarpa) are a natural source of bioactive compounds, particularly anthocyanins, and can be consumed as a snack. This study characterized the impact of freeze drying and in vitro gastrointestinal digestion on the phenolic profile, antioxidant capacity, and α-glucosidase activity of the Natal plum (Carissa macrocarpa). The phenolic compounds were quantified using high performance liquid chromatography coupled to a diode-array detector HPLC-DAD and an ultra-performance liquid chromatograph (UPLC) with a Waters Acquity photodiode array detector (PDA) coupled to a Synapt G2 quadrupole time-of-flight (QTOF) mass spectrometer. Cyanidin-3-O-β-sambubioside (Cy-3-Sa) and cyanidin-3-O-glucoside (Cy-3-G) were the dominant anthocyanins in the fresh and freeze-dried Natal plum powder. Freeze drying did not affect the concentrations of both cyanidin compounds compared to the fresh fruit. Both cyanidin compounds, ellagic acid, catechin, epicatechin syringic acid, caffeic acid, luteolin, and quercetin O-glycoside from the ingested freeze-dried Natal plum powder was quite stable in the gastric phase compared to the small intestinal phase. Cyanidin-3-O-β-sambubioside from the ingested Natal plum powder showed bioaccessibility of 32.2% compared to cyanidin-3-O-glucoside (16.3%). The degradation of anthocyanins increased the bioaccessibility of gallic acid, protocatechuic acid, coumaric acid, and ferulic acid significantly, in the small intestinal digesta. The ferric reducing antioxidant power (FRAP), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) activities, and inhibitory effect of α-glucosidase activity decreased in the small intestinal phase. Indigenous fruits or freeze-dried powders with Cy-3-Sa can be a better source of anthocyanin than Cy-3-G due to higher bioaccessibility in the small intestinal phase.

Authentication Using Volatile Composition: A Proof-of-Concept Study on the Volatile Profiles of Fourteen Queensland Ciders

Although relatively small, the Australian cider industry has experienced significant growth in recent years. One of the current challenges in the industry is the lack of research specific to Australian ciders. Establishing baseline volatile organic compound (VOC) profiles of Australian cider is paramount to developing a better understanding of the industry. This understanding may ultimately be utilized for both the categorization and authentication of existing ciders, and the targeted modification of cider volatiles for the development and improvement of cider quality. This study utilized gas chromatography, coupled with mass spectrometry, to identify key VOCs present in 14 ciders sourced from four different manufacturers in Queensland, Australia. A total of 40 VOCs were identified across the ciders, with significant variation depending on the flavor and manufacturer. Principal component analysis indicated that the ciders were well-separated based on the manufacturer, supporting the prospect of using the volatile composition to discriminate between cider manufacturers. Furthermore, hierarchical cluster analysis highlighted the commonalities and differences in cider composition between different manufacturers, which may be indicative of the varying ingredients and manufacturing processes used to create the ciders. Future studies profiling the volatile composition of larger numbers of Australian ciders are recommended to support the use of this analytical technique for authentication purposes. Likewise, exploration of the relationship between specific processes and VOCs is recommended to fortify an understanding of how to optimize cider production to improve consumer satisfaction.

High-Temperature Semi-Dry and Sweet Low Alcohol Wine-Making Using Immobilized Kefir Culture

Low alcohol wines (≤10.5% vol) represent novel wine products steadily gaining the commercial market interest. Considering the technological advancements of immobilized systems in association with the drastic reduction of industrial operational costs in high-temperature wine-making in regions with tropical climate or hot summer periods, the aim of the present study was to assess the fermentation efficiency of both wet and freeze-dried immobilized kefir culture on natural supports in low alcohol wine production at high temperatures (>30 °C). Immobilized kefir culture was evaluated and compared to free cells in repeated batch fermentations for 3 months, indicating high operational stability, and found suitable for simultaneous alcoholic and malolactic low alcohol wine fermentation at temperatures up to 45 °C. High ethanol productivity [up to 55.3 g/(Ld)] and malic acid conversion rates (up to 71.6%), which could be adopted by the industrial sector, were recorded. Principal Component Analysis (PCA) revealed that the state of the cells rather than the nature of kefir culture affected significantly the content of minor volatiles determined by Head Space Solid-Phase Microextraction (HS-SPME) Gas Chromatography–Mass Spectrometry (GC/MS) analysis. Notably, all new products were of high quality and approved by the sensory panel. The results suggested a high industrial potential of the proposed technology in semi-dry low alcohol wine-making at 37 °C and in developing novel wine products with a sweet (liquoreux) character at 45 °C.

Spray-Dried Formulations Rich in Malvidin from Tintorera Grape Wastes: Characterization, Stability, and Storage

This research was focused on developing means of Tintorera grape (Vitis vinifera L.) waste recovery, devising new value-added uses for that material and optimizing of anthocyanin-rich formulations by spray-drying in order to obtain novel ingredients, all for food industry use. First, the identification of phenolic compounds in Tintorera grape extracts by HPLC-DAD-ESI-MSn enabled characterization of the raw material’s health-promoting characteristics. Maintaining the spray-dried products for 4 weeks’ storage enabled study of the formulation’s loss of anthocyanins and antioxidant properties due to drying process temperatures as well as analysis of the retention and stability of such compounds under different conditions (20 and 40 °C). Tintorera grapes presented a significant amount of Malvidin 3-O-hex (5.66 mg g−1 DW). Anthocyanins in spray-dried formulations were stable for 4 weeks. Optimal conditions in the spray-dryer facilitated the products’ antioxidant capacity; for instance, using 10% maltodextrin (w:v) at 90 °C inlet temperature had a little influence on the reduction in encapsulated malvidin 3-O-hex (15%) and presented 3.35 mg GAE g−1 DW of total polyphenol contents, 98.62 µmol Trolox (FRAP assay), and 39.97 µmol Trolox (DPPH assay). Principal component analyses (PCA) showed a high degree of dependence between anthocyanin content and maintenance of antioxidant capacity during storage. These results offer a promising alternative for the industrial management of wine-making wastes in order to implement a sustainable protocol for development of Tintorera grape extracts rich in bioactive compounds for new beverages and functional foods.

Functional Ingredients from Agri-Food Waste: Effect of Inclusion Thereof on Phenolic Compound Content and Bioaccessibility in Bakery Products

Reducing food loss and waste is among the efforts to relieve the pressure on natural resources and move towards more sustainable food systems. Alternative pathways of food waste management include valorization of by-products as a source of phenolic compounds for formulation of functional foods. Bakery products may act as an optimal carrier of phenolic compounds upon fortification. The aim of this paper is to present and discuss the effect that the inclusion of functional ingredients from agri-food waste can have on phenolic content and bioaccessibility in bakery products. To this aim, methods for the recovery of phenolic compounds from agri-food waste are presented, and fortification of bakery products by waste from fruits, vegetables, and seed crops is discussed. Bioaccessibility studies on fortified food products are considered to identify gaps and needs in developing sustainable healthy foods. Fruit and vegetable by-products are among the food wastes mostly valorized as functional ingredients in bakery product formulation. Agri-food waste inclusion level has shown to correlate positively with the increase in phenolic content and antioxidant capacity. Nevertheless, further studies are required to assess bioaccessibility and bioavailability of phenolic compounds in enriched food products to estimate the potential of agri-food waste in promoting human health and well-being.

Effects of drying methods on plant lipid compounds and bulk isotopic compositions

RATIONALE

Plant lipid biomarkers, such as plant waxes and terpenoids, and the stable isotopic composition of bulk leaves are widely used in both modern and paleoclimate studies for tracking vegetation and climate. However, the effects of different drying methods on the preservation of plant lipid biomarkers and the stable isotopic compositions of leaves are less explored. Here, we investigated various drying methods for the measurement of plant lipid concentrations and bulk leaf isotopic compositions.

METHODS

Leaves from four tree species (Acer rubrum, Pinus sylvestris, Platanus occidentalis, and Taxodium distichum) were collected and dried using air, an oven, a freeze-dryer, and a microwave. We compared concentrations of leaf waxes and terpenoids and carbon (δ¹³ C) and nitrogen (δ¹⁵ N) isotopic compositions of leaves by different drying methods.

RESULTS

The air, oven, freeze-dryer, and microwave drying methods did not affect lipid concentrations significantly, and only a few homologues differed (38.1% or 41.8 μg/g on average) possibly due to biological variations or enhanced extraction efficiencies. The δ¹³ C values were not affected by drying methods, whereas the δ¹⁵ N values in oven-dried leaves in some species were higher by 0.2-0.7‰ than those obtained by other methods. Though small, we attribute these patterns to loss of leaf compounds with lower isotope ratios during oven-drying.

CONCLUSIONS

Based on our results, each drying technique yielded equivalent results for all plant wax and terpenoid concentrations and bulk leaf δ¹³ C values; however, oven-drying modified the δ¹⁵ N values.

Recent advances in postharvest technology of the wine grape to improve the wine aroma

Postharvest techniques are widely used for the handling and storage of fresh horticultural crops. Some of these techniques are interesting for use with wine grapes to improve the quality of wine. In this review, we consider the postharvest techniques that are already commercially used in the wine sector and others that may be significant in inducing or extracting the aroma from grapes to produce high-quality wines. Precooling consists of rapidly lowering the grape temperature, which allows the preservation/increase of volatile organic compounds (VOCs). We also discuss sustainability. Partial dehydration consists of the partial removal of water from grapes, and if a suitable environment is adopted it can be used to produce and extract berry VOCs. As a solid, carbon dioxide is used in wine processing for the rapid cooling of grapes and, as a gas, it is used for carbonic maceration. Ozone has been used for sanitation purposes in wineries for a long time, but more recently it has been used to produce wine without sulfite addition and to increase the aromatic quality of wine grapes. Ethylene application is not used commercially for wine grapes, but promising results in terms of phenolic extraction and aromatic changes in grapes are discussed. A comparison among the proposed techniques is reported in terms of grape aromatic quality and process features. The proposed techniques could help a winemaker to maintain or induce aromatic compounds in grape berries before the vinification process. The choice depends on the desired wine and economic consistency. © 2018 Society of Chemical Industry.

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.

Characterization of dried horseradish leaves pomace: phenolic compounds profile and antioxidant capacity, content of organic acids, pigments and volatile compounds

Horseradish (Armoracia rusticana) leaves pomace, which contains high-value bioactive compounds, is the product resulting from pressing horseradish leaves for juice production. The aim of the current research was to investigate the effect of convective, microwave-vacuum and freeze-drying on the content of bioactive compounds in horseradish leaves pomace. Convective hot air-drying was performed at 40, 60 and 80 °C. The total phenolic content (TPC), total flavonoid content (TFC), total flavan-3-ol content, total phenolic acid content, total flavonol content, chlorophylls and total carotenoids, and antioxidant activity were determined by spectrophotometric methods. Individual profiles of phenols and organic acids are estimated by high-performance liquid chromatography (HPLC), but volatile compounds are estimated by gas chromatography (GC). Totally, 14 individual phenolic compounds, 8 organic acids, and 49 volatile compounds were analysed in the studied samples. The main phenolic compound identified in horseradish leaves pomace was rutin (3231 mg/100 g DW), among organic acids—quinic and malic acids, and volatile compounds—allyl isothiocyanate, 3-butenenitrile and benzyl alcohol. In the drying process, the content of some (total flavan-3-ols, total carotenoids content) compounds increased, but others (TPC, total organic acids content) decreased, and it was drying method-dependent. Freeze-drying caused the reduction of TPC by 29%, whereas convective drying by 53–59%. Fresh pomace contains such isothiocyanates as allyl isothiocyanate and butyl isothiocyanate, which were completely lost in the drying process. Freeze-drying allowed the best retention of various phenolic and volatile compounds in horseradish leaves pomace.

Changes in volatile flavor compounds of peppers during hot air drying process based on headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS)

BACKGROUND

Flavor plays a critical role in defining sensory and consumer acceptance of dried pepper, and it can be affected by temperature and moisture content during hot air drying (HAD). Thus, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was used to analyze changes in volatile compounds of pepper during the HAD process with different drying temperatures.

RESULTS

A total of 45 volatile flavor compounds were identified, including 11 esters, 11 aldehydes, nine alcohols, five ketones, three furans, three acids, two pyrazines, and one ether. The results showed that with the loss of moisture during drying, aldehydes and alcohols decreased, esters initially increased and then decreased. However, propyl acetate, 2,3-butanediol, 2-acetylfuran, and 2-methylpyrazine increased. Moreover, drying temperature was closely related to the change of volatile flavor compounds. Aldehydes, alcohols, and some other volatile flavor compounds (methyl salicylate, ethyl acetate, 2-methylpyrazine, dipropyl disulfide) decreased with an increase of temperature (60-80 °C) at the same moisture content, while high temperature could promote the formation of ethyl octanoate, methyl octanoate, benzaldehyde, furfurol, acetal, 5-methylfurfural, and 2-acetylfuran. Based on principal components analysis and heat map clustering analysis, peppers dried at 70 or 80 °C presented similar composition, and the loss of volatile flavor compounds was more than samples died at 60 °C during the HAD process.

CONCLUSION

Overall, the flavor quality of peppers dried at 60 °C was better than that of other treatments during the HAD process. HS-GC-IMS was a reliable and effective means of analyzing volatile flavor compounds in peppers during the drying process. © 2020 Society of Chemical Industry.

Toward a standardised protocol for the stable isotope analysis of scleractinian corals

RATIONALE

The stable isotope analysis of carbon and nitrogen is a powerful tool in many ecological studies, but different sample treatments may affect stable isotope ratios and hamper comparisons among studies. The goal of this study was to determine whether treatments that are commonly used to prepare scleractinian coral samples for stable isotope analysis yield different δ¹⁵ N and δ¹³ C values, and to provide guidelines toward a standardised protocol.

METHODS

The animal tissues and Symbiodiniaceae of two symbiotic scleractinian coral species (Stylophora pistillata and Porites lutea) were divided into subsamples to test the effects of the drying method, lipid extraction, acidification treatment and water washing. All the subsamples were analysed for their δ¹⁵ N and δ¹³ C values, using continuous flow elemental analyser/isotope ratio mass spectrometry.

RESULTS

The drying method and lipid extraction treatment had no substantial effects on the δ¹⁵ N and δ¹³ C values of Symbiodiniaceae and animal tissues. Acid treatment did cause significant differences in δ¹³ C values (mean differences ≤0.5‰, with individual samples becoming up to 2.0‰ more negative), whereas no ecologically significant differences were observed in δ¹⁵ N values. Animal tissue δ¹³ C values may vary depending on whether samples are washed or not.

CONCLUSIONS

To move towards a standardised protocol in coral research, we recommend using an available drying method (as they are equally acceptable) for the stable isotope analysis of scleractinian corals, examining the need for lipid extraction on a case-by-case basis, performing a direct acidification of Symbiodiniaceae and animal tissues, and avoiding washing animal tissue with distilled water.

Changes in soil water availability in vineyards can be traced by the carbon and nitrogen isotope composition of dried wines

The grapevine is one of the most important edible fruit plants cultivated worldwide, and it is highly sensitive to changes in the soil water content. We studied the total carbon and nitrogen contents and stable isotope compositions (C/N_WSR, δ¹³C_WSR and δ¹⁵N_WSR values) of the solid residues obtained by freeze-drying wines produced from two white grapevine cultivars (Vitis vinifera L. cv Chasselas and Petite Arvine) field grown under different soil water regimes while maintaining other climatic and ecopedological conditions identical. These experiments simulated the more frequent and extended climate change-induced periods of soil water shortage. The wines were from the 2009-2014 vintages, produced using the same vinification procedure. The plant water status, reflecting soil water availability, was assessed by the predawn leaf water potential (Ψ_pd), monitored in the field during the growing seasons. For both wine varieties, the δ¹³C_WSR values are highly correlated with Ψ_pd values and record the soil water availability set by soil water holding capacity, rainfall and irrigation water supply. These relationships were the same as those observed for the carbon isotope composition of fruit sugars (i.e., must sugars) and plant water status. In Chasselas wines, the nitrogen content and δ¹⁵N_WSR values decreased with soil water deficit, indicating control of the flux of soil-water soluble nutrients into plants by soil water availability. Such a correlation was not found for Petite Arvine, probably due to different N-metabolism processes in this genetically atypical cultivar. The results presented in this study confirm and generalize what was previously found for red wine (Pinot noir); the carbon isotope composition of wine solid residues is a reliable indicator of the soil and the plant water status and thus can be used to trace back local climatic conditions in the vineyard's region. In most wines (except Petite Arvine) the C/N_WSR and δ¹⁵N_WSR values are indicators of the origin of the nitrogen supplied to the plant's fruit (grape) that can be used to assess the N dynamics in the soil-water-plant system.

Effects of Dietary Fibre from the Traditional Indonesian Food, Green Cincau (Premna oblongifolia Merr.) on Preneoplastic Lesions and Short Chain Fatty Acid Production in an Azoxymethane Rat Model of Colon Cancer

Green cincau (Premna oblongifolia Merr.) is a traditional food of Indonesia and provides a natural source of dietary fibre and antioxidants. This study evaluated the ability of green cincau, and other dietary fibres with or without the addition of anti-oxidant, epigallocatechin-3-gallate (EGCG), to prevent colorectal cancer in a 12 week azoxymethane (AOM) rat model. While all dietary treatments stimulated short chain fatty acid production (SCFA) in the digesta and faeces, no one treatment was able to significantly protect against aberrant crypt formation (ACF), when compared to the control diet. However, feeding green cincau leaves or extracts did not result in an increase in ACF compared to the control diet. Unexpectedly, when the dietary fibre source was pectin, 0.1% EGCG increased proliferative activity and liver lipid peroxidation when compared to the control diet containing cellulose. Examination of faecal microbial communities identified the presence of short chain acid producing bacteria, but a distinct community profile was not observed from any individual diet group. Overall, this research implies that combining dietary fibre with an antioxidant does not automatically equate to a beneficial response. Further work is required to investigate the health-promoting properties of green cincau.

Thermal inactivation kinetics and effects of drying methods on the phenolic profile and antioxidant activities of chicory (Cichorium intybus L.) leaves

The thermal inactivation kinetics of enzymes, including polyphenol oxidase (PPO) and peroxidase (POD), in chicory (Cichorium intybus L.) leaves were evaluated. In addition, the influences of different drying techniques (shade drying, hot air drying and freeze drying) on the phenolic profiles and antioxidant activities of chicory leaves were determined. The antioxidant activities of chicory leaves were evaluated on the basis of their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, reducing power, and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity. The results showed that the activation energy for PPO and POD inactivation were 123.00 kJ/mol and 78.99 kJ/mol, respectively. Preliminary treatment with hot water for 3 min at 90 °C was beneficial for preserving the phenolics present in fresh leaves. Hot air drying was better for the phenolics preservation. The hot air-dried and freeze-dried leaves possessed good antioxidant activities. The leaves with higher phenolics contents had better antioxidant activities, which indicated that the preservation of the phenolics was important for maintaining the antioxidant activity of chicory leaves.