Characterization of Organic Acids and Phenolic Compounds of Cereal Vinegars and Fruit Vinegars in China

Fruit vinegar as a promising source of natural anti-inflammatory agents: an up-to-date review

OBJECTIVES

Fruit vinegar is one of the most famous fruit byproducts worldwide with several unique properties. There are two types of fruit vinegar, artisanal and industrial, for consumers to choose from. This review aims to assess for the first time the phytochemistry of fruit vinegar and its anti-inflammatory effects.

METHOD

The present work was conducted based on a literature search that selected the relevant papers from indexed databases such as Scopus, Science Direct, MDPI, PubMed, Hindawi, and Web of Science. We used numerous terms to assure a good search in different databases, including fruit vinegar, phytochemistry, bioavailability and bioaccessibility, and anti-inflammatory effect. All articles were selected based on their relevance, quality, and problematic treatment.

RESULTS

Literature data have shown that vinegar has a long medicinal history and has been widely used by different civilizations, due to its richness in bioactive molecules, vinegar plays an important role in the prevention and treatment of various inflammatory diseases, including atopic dermatitis, mastitis, asthma, arthritis, acute pancreatitis, and colitis. Fruit vinegar consumption benefit is highly dependent on its chemical composition, especially organic acids and antioxidants, which can act as nutraceuticals.

CONCLUSION

Fruit vinegar has a rich chemical composition, including organic acids that can be transformed in the digestive system into compounds that play an important role in health-promoting features such as anti-inflammatory effects throughout the control of intestinal microbiota and pro-inflammatory cytokine production.

Exploring the Bioactive Compounds in Some Apple Vinegar Samples and Their Biological Activities

Apple vinegar is highly recommended for nutrition due to its health benefits and bioactive components. However, the apple cultivar greatly influences the quality of the vinegar. In this research, our focus was on examining the impact of four different apple cultivars on the physicochemical attributes, chemical composition, as well as biological properties-including antidepressant and anti-inflammatory activities-of vinegar. Interestingly, the physicochemical properties of vinegar and the contents of acetic acid and polyphenols depend on the apple cultivars. HPLC chromatographic analysis showed that citric acid (820.62-193.63 mg/100 g) and gallic acid (285.70-54.40 µg/g) were mostly abundant in the vinegar samples. The in vivo results showed that administration of Golden Delicious apple vinegar (10 mL/kg) to adult Wistar rats reduced carrageenan-induced inflammation by 37.50%. The same vinegar sample exhibited a significant antidepressant effect by reducing the rats' immobility time by 31.07% in the forced swimming test. Due to its high acidity, Golden Delicious vinegar was found to be more effective against bacteria, particularly Bacillus subtilis and Candida albicans, resulting in a MIC value of 31.81 mg/mL. Furthermore, the antioxidant activity of various vinegar samples was found to be powerful, displaying optimal values of IC50 = 65.20 mg/mL, 85.83%, and 26.45 AAE/g in the DPPH, β-carotene decolorization and TAC assays, respectively. In conclusion, the apple cultivars used in this study impact the chemical composition and biological activities of vinegar, which may help demonstrate the importance of raw material selection for the production of vinegar.

Protective mechanism of fruit vinegar polyphenols against AGEs-induced Caco-2 cell damage

Accumulation of advanced glycation end products (AGEs) is linked with development or aggravation of many degenerative processes or disorders. Fruit vinegars are rich in polyphenols that can be a good dietary source of AGEs inhibitors. In this study, eight kinds of vinegars were prepared. Among them, the highest polyphenol and flavonoid content were orange vinegar and kiwi fruit vinegar, respectively. Ferulic acid, vanillic acid, chlorogenic acid, p-coumaric acid, caffeic acid, catechin, and epicatechin were main polyphenols in eight fruit vinegars. Then, we measured the inhibitory effect of eight fruit vinegars on fluorescent AGEs, and found that orange vinegar had the highest inhibitory rate. Data here suggested that orange vinegar and its main components catechin, epicatechin, and p-coumaric acid could effectively reduce the level of ROS, RAGE, NADPH and inflammatory factors in Caco-2 cells. Our research provided theoretical basis for the application of orange vinegar as AGEs inhibitor.

Characterization of Fruit Vinegars via Bioactive and Organic Acid Profile Using Chemometrics

Vinegar has been known as a traditional remedy since ancient times. In addition to being used as a flavoring and aroma enhancer in world cuisines, it has attracted more and more attention due to its bioactive potential and health properties. Although the most common use is apple cider vinegar together with grape vinegar, vinegar produced from red fruits has come to the fore due to their health purposes. Rosehip, pomegranate, fig, guelder-rose, blackberry, raspberry, and blueberry vinegars were evaluated regarding the organic acid content, phenolic compound content, and bioactive potential to assess their health potential and associated contents. Acetic acid, citric acid, succinic acid, and malic acid were determined as prominent organic acids in the vinegar samples. In contrast, gallic acid, vanillic acid, protocatechuic acid, and ferulic acid were dominant regarding phenolic compounds. Raspberry, guelder-rose, and pomegranate vinegars came forth regarding their bioactive content and potential. The discriminative parameters of the vinegar samples were pH, total acidity, dL-isocitric acid, gallic acid, and hydroxybenzoic acid. Fruit vinegars were determined to have a notable bioactive content compared to apple and grape vinegars. The use of these vulnerable bioactive materials in vinegar fermentation could provide an effective way for nutrition and raw material resourcing.

Sugar and acid profile of loquat (Eriobotrya japonica Lindl.), enzymes assay and expression profiling of their metabolism-related genes as influenced by exogenously applied boron

Soluble sugars and organic acids are the most abundant components in ripe fruits, and they play critical roles in the development of fruit flavor and taste. Some loquat cultivars have high acid content which seriously affect the quality of fruit and reduce the value of commodity. Consequently, studying the physiological mechanism of sugar-acid metabolism in loquat can clarify the mechanism of their formation, accumulation and degradation in the fruit. Minerals application has been reported as a promising way to improve sugar-acid balance of the fruits. In this study, loquat trees were foliar sprayed with 0.1, 0.2 and 0.3% borax, and changes in soluble sugars and organic acids were recorded. The contents of soluble sugars and organic acids were determined using HPLC-RID and UPLC-MS, respectively. The activities of enzymes responsible for the metabolism of sugars and acids were quantified and expressions of related genes were determined using quantitative real-time PCR. The results revealed that 0.2% borax was a promising treatment among other B applications for the increased levels of soluble sugars and decreased acid contents in loquats. Correlation analysis showed that the enzymes i.e., SPS, SS, FK, and HK were may be involved in the regulation of fructose and glucose metabolism in the fruit pulp of loquat. While the activity of NADP-ME showed negative and NAD-MDH showed a positive correlation with malic acid content. Meanwhile, EjSPS1, EjSPS3, EjSS3, EjHK1, EjHK3, EjFK1, EjFK2, EjFK5, and EjFK6 may play an important role in soluble sugars metabolism in fruit pulp of loquat. Similarly, EjPEPC2, EjPEPC3, EjNAD-ME1, EjNAD-MDH1, EjNAD-MDH5-8, EjNAD-MDH10, and EjNAD-MDH13 may have a vital contribution to malic acid biosynthesis in loquat fruits. This study provides new insights for future elucidation of key mechanisms regulating soluble sugars and malic acid biosynthesis in loquats.

Dynamics of Physicochemical Properties, Functional Compounds and Antioxidant Capacity during Spontaneous Fermentation of Lycium ruthenicum Murr. (Qinghai–Tibet Plateau) Natural Vinegar

Functional fermented fruit drinks are known worldwide for their health-promoting potential. Black wolfberry (BW) has high nutritional value, and its relative product development can be enriched through fermentation technology, so that its market might be broadened. Total acid, sugars, proteins, enzymes, anthocyanins, flavonoids, polyphenols, organic acids and DPPH free radical scavenging ability (DPPH) were tracked and determined by colorimetric method and HPLC during spontaneous fermentation of BW vinegar. The antioxidant capacity in vitro of BW vinegar was evaluated based on the dynamics of antioxidant contents and DPPH. The results showed that total acid continuously increased during fermentation, yet total sugar and reducing sugar shared a similar decreasing trend. The composition of samples differed in terms of total anthocyanins, total flavonoid, total polyphenol, total protein, superoxide dismutase (SOD), amylase, organic acids and DPPH through spontaneous fermentation. Functional compounds including total polyphenol, total flavonoid and three organic acids (γ-aminobutyric acid, lactic acid and gallic acid) played the main roles in antioxidation. Unexpectedly, SOD and ascorbic acid as antioxidants did not correlate with DPPH, but they were rich in the final products at 754.35 U/mL and 3.39 mg/mL, respectively. Generally, the quality of BW vinegar has been improved based on analyzing dynamics on functional compounds, organic acids and antioxidant capacity, which proves that BW vinegar obtained by spontaneous fermentation should be a potential source of fermented food with antioxidant effects for consumers.

Contribution to the Evaluation of Physicochemical Properties, Total Phenolic Content, Antioxidant Potential, and Antimicrobial Activity of Vinegar Commercialized in Morocco

Vinegar is a natural product widely used in food and traditional medicine thanks to its physicochemical properties and its richness in bioactive molecules. However, its direct use by consumers can have complications and undesirable effects. Therefore, this study contributes to investigating the physicochemical and biological properties of eleven vinegars marketed in Morocco. Determination of pH, acetic acid, conductivity, total soluble solids and alcohol content in vinegar was carried out. The polyphenols (TP), flavonoids (TF), and condensed tannins (CT) content was determined, and their antioxidant activities were evaluated using 2,2-diphenyl-1-picryl Hydrazyl (DPPH), Ferric Reducing Antioxidant Power (FRAP) and Phosphomolybdenum Reduction Assay (TAC). Then, the antimicrobial activity was studied against four pathogenic bacteria and two fungal strains, using the disk diffusion and the microdilution method. This study showed a wide range of acetic acid values from 0.65 ± 0.29 to 5.15 ± 0.20%. The high value of TP, TF, and CT in our samples V10, V9, and V4 was 655.00 ± 22.2 µgGAE/mL, 244.53 ± 11.32 µgQE/mL and 84.63 ± 1.00 µgTAE/mL, respectively. The tested strains showed variable sensitivities to the different samples with inhibition zones ranging from 6.33 ± 2.08 to 34.33 ± 0.58 mm. The lowest minimum inhibition concentrations were recorded against Staphylococcus aureus ATCC29213 ranging from 1.95 to 7.81 µL/mL. While Aspergillus niger ATCC16404 showed resistance against all of the analyzed samples. In general, vinegar commercialized in Morocco presents a variable range of products with variable properties. Indeed, must take into account this diversity when using it. A future study is needed to identify the phytochemical composition that will further the comprehension of this variability and contribute to its valorization.

Fruits Vinegar: Quality Characteristics, Phytochemistry, and Functionality

The popularity of fruits vinegar (FsV) has been increased recently as a healthy drink wealthy in bioactive compounds that provide several beneficial properties. This review was designed in the frame of valorization of fruits vinegar as a by-product with high value added by providing overall information on its biochemical constituents and beneficial potencies. It contains a cocktail of bioactive ingredients including polyphenolic acids, organic acids, tetramethylperazine, and melanoidins. Acetic acid is the most abundant organic acid and chlorogenic acid is the major phenol in apple vinegar. The administration of fruits vinegar could prevent diabetes, hypercholesterolemia, oxidative stress, cancer, and boost immunity as well as provide a remarkable antioxidant ability. The production techniques influence the quality of vinegar, and consequently, its health benefits.

Fast monitoring total acids and total polyphenol contents in fermentation broth of mulberry vinegar using MEMS and optical fiber near-infrared spectrometers

This study evaluated the potential of Micro-Electro-Mechanical System (MEMS) and optical fiber Near-Infrared (NIR) spectrometers as a rapid method for monitoring total acids (TA) and total polyphenol content (TPC) in the fermentation process of mulberry vinegar. The NIR spectrometers Digital Light Processing (DLP) NIRscan Nano EVM (MEMS instrument) were used for this purpose, and another NIR spectrometer NIRQuest 512 was used for comparison. The standard Normal Variate (SNV) was selected as the best method used to pre-process spectra, and the competitive adaptive reweighted sampling (CARS) was applied to optimize wavelength variables, which were then subjected to partial least squares (PLS) regression. The results showed that TA and TPC could be determined. For TA, NIRQuest 512 provided a good predictive performance with the root-mean-square error of prediction set (RMSEP) of 0.22% and the R-squared of prediction set (R²_P) of 0.977, whiles DLP NIRscan Nano EVM obtained the RMSEP of 0.32% and R²p of 0.950. For TPC, the NIRQuest 512 provided a predictive performance with the RMSEP of 8.11 mgGAE/L (mg gallic acid equivalent/L) and R²_P of 0.820, and DLP NIRscan Nano EVM had the RMSEP of 8.22 mg GAE/L and R²p of 0.800. In conclusion, the low-price MEMS NIR instruments DLP NIRscan Nano EVM can be applied to monitor TA and TPC in the fermentation broth of mulberry vinegar.

Strategies to Improve the Potential Functionality of Fruit-Based Fermented Beverages

It is only recently that fermentation has been facing a dynamic revival in the food industry. Fermented fruit-based beverages are among the most ancient products consumed worldwide, while in recent years special research attention has been granted to assess their functionality. This review highlights the functional potential of alcoholic and non-alcoholic fermented fruit beverages in terms of chemical and nutritional profiles that impact on human health, considering the natural occurrence and enrichment of fermented fruit-based beverages in phenolic compounds, vitamins and minerals, and pro/prebiotics. The health benefits of fruit-based beverages that resulted from lactic, acetic, alcoholic, or symbiotic fermentation and specific daily recommended doses of each claimed bioactive compound were also highlighted. The latest trends on pre-fermentative methods used to optimize the extraction of bioactive compounds (maceration, decoction, and extraction assisted by supercritical fluids, microwave, ultrasound, pulsed electric fields, high pressure homogenization, or enzymes) are critically assessed. As such, optimized fermentation processes and post-fermentative operations, reviewed in an industrial scale-up, can prolong the shelf life and the quality of fermented fruit beverages.

Antioxidants, inhibits the growth of foodborne pathogens and reduces nitric oxide activity in LPS-stimulated RAW 264.7 cells of nipa palm vinegar

Nipa palm vinegar (NPV) made from the sap of nipa palm (Nypa fruticans Wurmb.) has long been used as a local food seasoning and folk medicine. This study compared the bioactive compounds, antioxidant, in vitro anti-inflammatory and antimicrobial activities of three NPVs obtained from different plantations based on varied soil and water salinity levels, including fresh water NPV, brackish water NPV and saline water NPV. The analysis results revealed that total phenolic content of saline water NPV had statistically significantly lower than both fresh water and brackish water NPV (p < 0.0001). Furthermore percentage of acetic acid in brackish water NPV had statistically significantly lower than both fresh water and saline water. NPV (p = 0.002). Nevertheless, total flavonoid and pH, were not significantly different (p = 0.144 and 0.066, respectively). The antioxidant activities using three ABTS, DPPH and FRAP methods displayed similar patterns, in which saline water NPV showed the highest antioxidant activities, followed by brackish water and fresh water NPV, respectively. Antimicrobial activity was examined for seven enteropathogenic bacteria. The tested NPVs were found inhibitive against all test cultures with a minimum inhibitory concentration (MIC) of ≤ 7.8 µL/mL. The cytotoxicity of the NPV obtained from different plantations by MTT assay revealed low cytotoxicity. Anti-inflammatory activity was also carried out through the inhibition of nitric oxide production. The fresh water NPV exhibited the highest anti-inflammatory activity with IC50 17.59 ± 0.17 µL/mL, followed by saline and brackish water NPV with IC50 18.12 ± 0.49 and 28.29 ± 2.64 µL/mL, respectively. The findings indicated that NPV from different soil salinities could potentially be natural functional food and developed to antimicrobial and anti-inflammatory medicinal agents with safety.

Novel Yeasts Producing High Levels of Conjugated Linoleic Acid and Organic Acids in Fermented Doughs

Traditional fermented foods are obtained by a complex consortium of autochthonous microorganisms producing a wide variety of bioactive compounds, thus representing a reservoir of strains with new functional properties. Here, doughs obtained using five different wholegrain flours were singly fermented with selected yeast strains, which were evaluated for their functional traits. Lactate, volatile fatty acids and conjugated linoleic acid isomers produced by fermented doughs were detected by HPLC, while dough anti-inflammatory capacity was measured on human peripheral blood mononuclear cells by flow cytometry. Yeast potential probiotic activity was assessed by evaluating their resistance to simulated gastric and intestinal fluids. For the first time we report evidence of yeast strains producing high levels of the conjugated linoleic acid (CLA) isomer CLA 10-12tc and propionic acid, which are known for their specific health benefits. Moreover, such yeast strains showed an anti-inflammatory capacity, as revealed by a significantly decreased production of the strongly pro-inflammatory cytokine IL-1β. All our Saccharomyces cerevisiae strains were remarkably resistant to simulated gastric and intestinal fluids, as compared to the commercial probiotic strain. The two strains S. cerevisiae IMA D18Y and L10Y showed the best survival percentage. Our novel yeast strains may be exploited as valuable functional starters for the industrial production of cereal-based innovative and health-promoting fermented foods.

Elucidation and Regulation of Polyphenols in the Smoking Process of Shanxi Aged Vinegar

Polyphenols (PPs) are the main contributors to the health functions of Shanxi aged vinegar (SAV) and are mainly produced during the smoking process. This study aimed to explore the feasibility of regulating the accumulation of total water-soluble PPs (TWSP) by changing environmental factors based on the distribution of PPs. A total of eleven PPs, such as vanillin, vanillic acid, and (e)-ferulic acid, were detected during the smoking process. During the smoking process, the content of TWSP gradually increased and was accompanied by changes in environmental factors. Spearman correlation analysis and verification experiments showed that temperature, amino acids, and reducing sugars, as the main influencing factors, promoted the accumulation of TWSP. The in situ regulation strategy of changing environmental factors significantly increased the accumulation of TWSP by 12.24%.

Polyphenols Extracted from Shanxi-Aged Vinegar Inhibit Inflammation in LPS-Induced RAW264.7 Macrophages and ICR Mice via the Suppression of MAPK/NF-κB Pathway Activation

Shanxi-aged vinegar, a traditional Chinese grain-fermented food that is rich in polyphenols, has been shown to have therapeutic effects on a variety of diseases. However, there has been no comprehensive evaluation of the anti-inflammatory activity of polyphenols extracted from Shanxi-aged vinegar (SAVEP) to date. The anti-inflammatory activities of SAVEP, both in RAW 264.7 macrophages and mice, were extensively investigated for the potential application of SAVEP as a novel anti-inflammatory agent. In order to confirm the notion that polyphenols could improve inflammatory symptoms, SAVEP was firstly detected by gas chromatography mass spectrometry (GC-MS). In total, 19 polyphenols were detected, including 12 phenolic acids. The study further investigated the protective effect of SAVEP on lipopolysaccharide-induced inflammation in RAW264.7 macrophages and ICR mice. The results showed that compared with those of the model group, SAVEP could remarkably recover the inflammation of macrophage RAW264.7 and ICR mice. SAVEP can normalise the expression of related proteins via the suppression of MAPK/NF-κB pathway activation, inhibiting the expression of iNOS and COX-2 proteins, and consequently the production of inflammatory factors, thus alleviating inflammatory stress. These results suggest that SAVEP may have a potential function against inflammation.

GC × GC-MS analysis and hypolipidemic effects of polyphenol extracts from Shanxi-aged vinegar in rats under a high fat diet

Oxidative stress, inflammation and gut microbiota disorders can be induced by long-term high-fat diets (HFD). In order to confirm that polyphenols can improve these symptoms, polyphenols from Shanxi-aged vinegar (SAVEP) were extracted, and the components were detected by Comprehensive two-dimensional gas chromatography mass spectrometry (GC × GC-MS). 41 polyphenols include 18 phenolic acids and 17 polyphenols, which have not been reported. The mechanism of SAVEP on oxidative stress and inflammatory stress induced by HFD in rats and its regulating effect on intestinal flora disorder were studied. The results showed that SAVEP could significantly improve the lipid, inflammatory stress and oxidative stress related indicators compared with the Model group ("Model" refers to the group that successfully constructed a hyperlipidemia model by feeding HFD without any drugs or SAVEP in subsequent experiments.). In addition, SAVEP decreased the Firmicutes/Bacteroidetes ratio compared with the Model group, and elevated the relative abundance of beneficial bacteria. Conclusively, SAVEP can alleviate the oxidative stress and inflammatory stress caused by HFD, improving intestinal microbial disorders. The Spearman's correlation analysis revealed that Desulfovibrio, Lactobacillus and Akkermansia were correlated negatively with all of the inflammatory indicators, whereas Ruminococcus was the opposite. These results suggest that SAVEP may be a novel strategy against oxidative stress and inflammation, restoring the normal microbial community ecology of the gut and the treatment of metabolic syndromes.

Health Promoting Properties of Cereal Vinegars

Vinegar has been used for its health promoting properties since antiquity. Nowadays, these properties are investigated, scientifically documented, and highlighted. The health benefits of vinegar have been associated with the presence of a variety of bioactive components such as acetic acid and other organic acids, phenolic compounds, amino acids, carotenoids, phytosterols, vitamins, minerals, and alkaloids, etc. These components are known to induce responses in the human body, such as antioxidant, antidiabetic, antimicrobial, antitumor, antiobesity, antihypertensive, and anti-inflammatory effects. The diversity and levels of bioactive components in vinegars depend on the raw material and the production method used. Cereal vinegars, which are more common in the Asia-Pacific region, are usually made from rice, although other cereals, such as millet, sorghum, barley, malt, wheat, corn, rye, oats, bran and chaff, are also used. A variety of bioactive components, such as organic acids, polyphenols, amino acids, vitamins, minerals, alkaloids, melanoidins, butenolides, and specific compounds such as γ-oryzanol, tetramethylpyrazine, γ-aminobutyric acid, etc., have been associated with the health properties of cereal vinegars. In this work, the bioactive components and the related health effects of cereal vinegars are reviewed, and the most recent scientific literature is presented and discussed.

Changes of Physicochemical, Bioactive Compounds and Antioxidant Capacity during the Brewing Process of Zhenjiang Aromatic Vinegar

Zhenjiang aromatic vinegar (ZAV) is a kind of traditional fermented food worldwide. In this study, the changes of physicochemical properties, total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant activity (TAA) were evaluated during the brewing process of ZAV. In addition, the correlation between phenolic compound contents and antioxidant activities was investigated during the aging process (AP) of ZAV. The results showed that total acids, non-volatile acids, and amino nitrogen increased gradually during the brewing process. Reducing sugar decreased sharply at the early fermentation stage and then increased during the AP. Meanwhile, TPC, TFC, and TAA kept a very low level at the stage of alcohol fermentation (AF), and increased to the highest level at the sixth year of the AP. TAA has a high positive correlation with TPC and TFC during the brewing process of ZAV. In addition, the contents of p-hydroxybenzoic acid, vanillic acid, and catechin were higher than other phenolic compounds and reached the highest level at the sixth year of the AP, and were the main composition of phenolic compounds during the AP. Moreover, gallic acid, ferulic acid, and sinapic acid had the higher contribution at the early stage of the AP, and then declined to a lower level. Catechin, vanillic acid, and syringic acid had a higher contribution during the AP. These findings would be helpful in controlling the quality of vinegar and improving its functional properties.

Nutritional properties and biological activities of kiwifruit (Actinidia) and kiwifruit products under simulated gastrointestinal in vitro digestion

BACKGROUND

Kiwifruit is one of the most commercialized fruits on the international market, which has notable high nutritional and medicinal value with many health benefits. In addition to being consumed fresh, numerous kiwifruit products are popular, such as kiwifruit juice, vinegar, dried slices, jam, wine, yogurt, and jelly. Although many studies have described the nutritional properties of kiwifruit, investigations on the nutritional properties of kiwifruit products remain limited, especially for kiwifruit products made from raw kiwifruit.

METHODS

Nutritional properties and biological activities of kiwifruit and kiwifruit products, as well as the digestive and absorption characteristics of their nutritional substances, were investigated.

RESULTS

Kiwifruit, juice, wine, and vinegar were observed to be rich in vitamin C (VC) and polyphenol and exhibited high biological activities, whereas dried kiwifruit slices and jam showed higher amounts of mineral elements. During oral digestion, VC and polyphenol showed similar absorption characteristics, while mineral elements exhibited a number of different trends. A good release rate of all nutritional substances was observed during stomach digestion, while the release rate decreased in serum-available, colon-available, and post-colonic fractions. Eating dried slices and jam supplied high amounts of mineral elements, while eating kiwifruit supplied the most comprehensive nutritional substances. The biological activities detected in raw foodstuffs were much higher than those detected after in vitro digestion. Furthermore, kiwifruit and wine showed the highest biological activities, while dried kiwifruit slices showed the lowest biological activities.

CONCLUSION

These results increased our understanding of the nutritional properties of kiwifruit and its products, providing new information and scientific recommendations to consumers for kiwifruit consumption and to producers for kiwifruit production.

Antioxidant Activities, Phenolic Profiles, and Organic Acid Contents of Fruit Vinegars

Fruit vinegars are popular condiments worldwide. Antioxidants and organic acids are two important components of the flavors and health benefits of fruit vinegars. This study aimed to test the antioxidant activities, phenolic profiles, and organic acid contents of 23 fruit vinegars. The results found that the 23 fruit vinegars varied in ferric-reducing antioxidant power (FRAP, 0.15⁻23.52 μmol Fe(II)/mL), Trolox equivalent antioxidant capacity (TEAC, 0.03⁻7.30 μmol Trolox/mL), total phenolic content (TPC, 29.64⁻3216.60 mg gallic acid equivalent/L), and total flavonoid content (TFC, 2.22⁻753.19 mg quercetin equivalent/L) values. Among the 23 fruit vinegars, the highest antioxidant activities were found in balsamic vinegar from Modena (Galletti), Aceto Balsamico di Modena (Monari Federzoni), red wine vinegar (Kühne), and red wine vinegar (Galletti). In addition, polyphenols and organic acids might be responsible for the antioxidant activities of fruit vinegars. The most widely detected phenolic compounds in fruit vinegars were gallic acid, protocatechuic acid, chlorogenic acid, caffeic acid, and p-coumaric acid, with tartaric acid, malic acid, lactic acid, citric acid, and succinic acid the most widely distributed organic acids. Overall, fruit vinegars are rich in polyphenols and organic acids and can be a good dietary source of antioxidants.

Evaluation of Nutritional Compositions, Bioactive Compounds, and Antioxidant Activities of Shanxi Aged Vinegars During the Aging Process

Shanxi aged vinegar (SAV) is known as famous fermented food in China. During the brewing process, a large number of nutritional substances and bioactive compounds are produced, which have beneficial effects on human body. In this study, the contents of nutritional compositions including proteins, fats, carbohydrates, organic acids, and amino acids were determined in SAV samples. The antioxidant compounds and properties of SAV with different aging time were also evaluated. The results showed that the contents of proteins, crude fats, and carbohydrates in SAV were not changed with the aging time. Moreover, Alanine was the main component of amino acids in SAV, and the total contents of amino acids were increased with the aging time. Acetic acid and lactic acid were the predominant organic acids in SAV. The contents of acetic acid and lactic acid accounted for more than 90% of the total organic acids in SAV, which were increased during the aging process of 5 years. Furthermore, total phenols, flavonoids contents, and browning index in SAV were also increased during the aging time. These antioxidant compounds showed a high correlation with the antioxidant activities of SAV measured by ferric reducing antioxidant power and 2,2'-azino-bis(3-ethylbenzthi azoline-6-sulfonic acid) assays. The contribution of polyphenolic fractions and high molecular weight melanoidins to total antioxidant activities was similar (about 49% and 48%, respectively). Our findings would provide new insights to further explore the development of new vinegar-based functional foods.

PRACTICAL APPLICATION

The analysis of nutritional compositions, bioactive compounds, and antioxidant capacities in vinegars provides a theoretical basis for the function of SAV. It also provides references for further explore the development of new-type functional and healthy vinegars.

Bioactive Compounds in Cornelian Cherry Vinegars

We analyzed the effect of Cornelian cherry varieties differing in fruit color ('Yantaryi'-yellow fruits, 'Koralovyi'-coral fruits, 'Podolski'-red fruits) and the production method on the physicochemical and antioxidative properties of Cornelian cherry vinegars, and on their content of iridoids and polyphenols. Acetic fermentation was conducted by two methods: I) single-stage (spontaneous) acetic fermentation, without inoculation with microorganisms, and II) two-stage fermentation in which the first stage involved the use of Saccharomyces bayanus-Safspirit fruit yeast for alcoholic fermentation, and the second one included spontaneous acetic fermentation. Acetic acid, glycerol, individual iridoids, phenolic acids, flavonols, and anthocyanins were quantified by a high-performance liquid chromatography (HPLC) method. The antioxidative activity was determined based on the following tests: 2,2-Diphenyl-2-picryl-hydrazyl (DPPH•), 2,2'-Azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS•+), and ferric reducing antioxidant power (FRAP), while the total polyphenols content was determined using the Folin-Ciocialteu (F-C) reagent test. Both the Cornelian cherry variety and vinegar production method affected the antioxidative properties as well as concentrations of iridoids and polyphenols in the finished product. The concentration of total polyphenols (F-C) in vinegars ranged from 326.60 to 757.27 mg gallic acids equivalents (GAE)/100 mL vinegar, whereas the antioxidative activity assayed with the DPPH• and FRAP methods was the highest in the vinegars produced from the coral and red varieties of Cornelian cherry with the two-stage method. Loganic acid predominated among the identified iridoids, reaching a concentration of 185.07 mg loganic acid (LA)/100 mL in the vinegar produced in the two-stage fermentation from the coral-fruit variety. Caffeoylquinic acid derivatives were the main representatives among the identified phenolic compounds. The results of this study demonstrate Cornelian cherry vinegars to be rich sources of biologically-active iridoids and phenolic compounds with antioxidative properties.