•Pronase and Viscozyme treatment changed the ratio of soluble to insoluble-bound phenolics.•Viscozyme was more effective than Pronase in releasing phenolic compounds.•Procyanidin dimer B was ...extracted with Viscozyme but not upon Pronase treatment.•Phenolics served as inhibitors of alpha-glucosidase and lipase.•Phenolics may act in prevention and/or management of diabetes and obesity.
Phenolics in food and agricultural processing by-products exist in the soluble and insoluble-bound forms. The ability of selected enzymes in improving the extraction of insoluble-bound phenolics from the starting material (experiment I) or the residues containing insoluble-bound phenolics (experiment II) were evaluated. Pronase and Viscozyme improved the extraction of insoluble-bound phenolics as evaluated by total phenolic content, antioxidant potential as determined by ABTS and DPPH assays, and hydroxyl radical scavenging capacity, reducing power as well as evaluation of inhibition of alpha-glucosidase and lipase activities. Viscozyme released higher amounts of gallic acid, catechin, and prodelphinidin dimer A compared to Pronase treatment. Furthermore, p-coumaric and caffeic acids, as well as procyanidin dimer B, were extracted with Viscozyme but not with Pronase treatment. Solubility plays an important role in the bioavailability of phenolic compounds, hence this study may assist in better exploitation of phenolics from winemaking by-products as functional food ingredients and/or supplements.
Free, esterified, etherified and insoluble-bound phenolics from three samples, namely meal from whole peanuts (MWP), meal from dry-blanched peanuts (MDBP) and peanut skin (PS) were evaluated for ...their total phenolic content (TPC), and phenolic profile using HPLC–DAD–ESI–MS
n
. The TPC was in the order of PS > MWP > MDBP. Among 37 compounds identified 10 were reported for peanuts for the first time. Proanthocyanidins were detected in peanut skin and MWP, but not in MDBP. The presence of peanut skin in MWP rendered up to 9.8-fold higher scavenging activity towards the DPPH radical as compared with MDBP. Phenolics from all samples and fractions showed inhibition of alpha-glucosidase and lipase activities, which are key enzymes involved in the absorption of glucose and triacylglycerols, respectively. Therefore, their antioxidant properties as well as their potential role in the management of diabetes and obesity makes them worthy of further consideration as functional food ingredients.
Bioactive compounds belonging to phenolic acids, flavonoids, and proanthocyanidins of grape juice and winemaking byproducts were identified and quantified by HPLC-DAD-ESI-MS n . The concentration of ...phenolic compounds in different grape cultivars was in the order Tempranillo > Cora > Syrah > Isabel. The insoluble-bound fraction was most prominent, contributing 63 and 79% to the total for Isabel and Tempranillo, respectively. Juice-processing byproducts had a higher content of free than esterified phenolics, but the opposite was noted for winemaking byproducts. Insoluble-bound phenolics were up to 15 and 10 times more effective as antioxidants than those of free and esterified fractions, respectively, as evaluated by the DPPH, ABTS, and H2O2 scavenging activities and reducing power determinations. In general, insoluble-bound phenolics (100 ppm) were more effective in inhibiting copper-induced human LDL-cholesterol oxidation than free and esterified phenolics, exhibiting equal or higher efficacy than catechin. Phenolic extracts from all fractions inhibited peroxyl radical-induced DNA strand breakage. These findings shed further light for future studies and industrial application of grape byproducts, which may focus not only on the soluble phenolics but also on the insoluble-bound fraction.
Plant foods, their products and processing by-products are well recognized as important sources of phenolic compounds. Recent studies in this field have demonstrated that food processing by-products ...are often richer sources of bioactive compounds as compared with their original feedstock. However, their final application as a source of nutraceuticals and bioactives requires addressing certain hurdles and challenges. This review discusses recent knowledge advances in the use of plant food processing by-products as sources of phenolic compounds with special attention to the role of genetics on the distribution and biosynthesis of plant phenolics, as well as their profiling and screening, potential health benefits, and safety issues. The potentialities in health improvement from food phenolics in animal models and in humans is well substantiated, however, considering the emerging market of plant food by-products as potential sources of phenolic bioactives, more research in humans is deemed necessary.
•Gamma irradiated peanut skins were microbiologically safe.•Free, esterified and insoluble-bound phenolics in peanut skin were identified and quantified.•Free phenolics and proanthocyanidins were the ...major phenolics in peanut skin.•Gamma-irradiation improved the antioxidant activity of the free phenolic fraction.•Molecular conversion, depolymerization, and cross-linking may explain the changes in the phenolics present.
The effects of gamma-irradiation on the microbial growth, phenolic composition, and antioxidant properties of peanut skin were evaluated. Gamma-irradiation at 5.0 kGy decreased the microbiological count of the product. Total phenolic and proanthocyanidin contents, ABTS radical cation, DPPH radical, H2O2, and hydroxyl radical scavenging capacities as well as the reducing power of the sample were increased upon gamma-irradiation in both the free and insoluble-bound phenolic fractions. However, a decrease in the esterified phenolics was noticed. The bioactivity of the free phenolics against in vitro human LDL-cholesterol oxidation and copper induced DNA strand breakage was improved upon gamma-irradiation. Phenolic acids, flavonoids, and proanthocyanidins were positively or tentatively identified by HPLC-DAD-ESI-MSn and their distribution was in the decreasing order of free > esterified > insoluble-bound forms. Procyanidin dimer A was increased in all phenolic fractions, whereas procyanidin dimer B decreased. Gamma-irradiation induced changes may be explained by molecular conversion, depolymerization, and cross-linking.
While biodiesel from jatropha oil is oxidation-sensitive and fluid, palm oil-biodiesel is more stable, but with sub-optimal fluid dynamics. Mixing these oils before reaction could be advantageous for ...reducing steps in production while generating biodiesel with desired cold-flow and stability properties. Here, we performed central composite designs to optimize the transesterification of jatropha and palm oil mixtures via conventional alkaline (CT) and ultrasound-assisted transesterification (UT), assessing the physicochemical properties of the biodiesel. Acid esterification of oil mixtures was followed by transesterification with NaOH and ethanol. The two-step conversion of jatropha and palm oil binary mixtures was successful. UT resulted in 93%-time reduction (4 min) in comparison to CT (60 min). The increased presence of jatropha oil improved the fluid dynamics of biodiesel. UT is a promising technology for synthesizing biodiesel in less time. The transesterification of binary mixtures is a direct and simple approach for reducing steps in biodiesel production.
The oxidative changes of peanuts subjected to the dry-blanching process were evaluated and compared with those of their in-shell counterparts. In general, the fatty acid profile was not influenced. ...The content of α-tocopherol decreased, but the remaining tocopherol homologs were unaffected. Nonanal, an oxidation product of oleic acid, increased. However, the contents of several volatile compounds with potential antioxidant properties were also increased. The higher oxidative stability of dry-blanched peanuts was demonstrated by accelerated tests as evaluated by peroxide value, thiobarbituric acid reactive substances (TBARS) and the induction period of cold-pressed oils and this was confirmed by the higher antioxidant properties of oils from such sample as evaluated by the DPPH radical scavenging activity. These results were further confirmed during long-term storage of dry-blanched and in-shell peanuts. The decrease of tocopherols in peanuts due to dry-blanching did not negatively influence their oxidative stability. In fact, dry-blanched peanuts showed higher stability as compared with in-shell peanuts; therefore, we suggest that loss of tocopherol might be less important than the generation of several volatile antioxidant compounds as well as possibly Maillard reaction products upon the dry-blanching process. These results may be of practical interest to the peanut and peanut oil industries.
Due to the strong bitter taste, sacha inchi seeds are usually consumed after roasting, which also contributes to the elimination of antinutrients. Sacha inchi plants fully adapted to cultivation ...under sub-tropical climate conditions were produced in southeastern Brazil. Our main goal was to evaluate the effect of dry heating (roasting) on the antinutrient content of these seeds. We also investigated the effects of the applied roasting treatments on the antioxidant activity, proximate composition and oxidative stability of the seeds. To the best of our knowledge, this is the first report on antinutrients of sacha inchi seeds cultivated under sub-tropical conditions, outside their native tropical environment. Except for saponins, which are not heat-labile compounds, the contents of all assessed antinutrients continually reduced with the increase in roasting temperature. Roasting improved antioxidant activity and phenolic content in the seeds at the highest temperature. Oxidation changes occurred in the seed oil, and they increased with temperature. However, maximum peroxide value was within the acceptable consumption limits. As a conclusion, roasting treatments can be applied to minimize the antinutrient potential in sacha inchi seeds. Knowledge on the composition and proper processing of sacha inchi cultivated under sub-tropical conditions may support future efforts focused on the development of new production areas.
Soybean oil is industrially obtained upon hexane extraction. In biodiesel production, soybean oil is submitted to phospholipid removal in order to improve its quality before transesterification. An ...extraction process was employed to produce ethanolic oil-rich miscella, which can be directly transesterified to produce biodiesel without prior refining. We assessed the oxidative stability of the miscella and three other soybean oils, namely degummed, alkali-refined, and refined–bleached–deodorized (RBD) oil.
In vitro
antioxidant assays as well as the identification and quantification of tocopherols and isoflavones were also performed. Although hexane-extracted oils showed higher tocopherol contents than miscella, this latter sample and its direct biodiesel demonstrated superior stability in accelerated tests. Miscella also outperformed hexane-extracted oils in all
in vitro
assays. This behavior can be explained by the presence of phenolic compounds with higher affinity to ethanol than hexane, which was confirmed by the identification of isoflavones glycitein, genistein, and acetyldaidzin, found only in miscella. This study showed that the ethanolic extraction of soybean oil generated a highly stable lipid feedstock for biodiesel manufacture.
•Phenolics of peanut skin (PS) and meal from dry-blanched peanuts (MDBP).•PS phenolics showed higher antiradical activity and reducing power than MDBP.•Phenolics of PS and MDBP showed antimicrobial ...activity against nine bacteria tested.•Phenolics of MDBP may serve better than those of PS as antimicrobial compounds.
Peanut skin (PS) and meal from dry-blanched peanuts (MDBP) were evaluated as sources of phenolic compounds. PS rendered the highest total phenolic content, antioxidant capacity towards ABTS radical cation, DPPH and hydroxyl radicals as well as reducing power. Phenolic acids were present in PS and MDBP whereas proanthocyanidins and monomeric flavonoids were found only in PS as identified by HPLC-DAD-ESI-MSn. Procyanidin-rich extracts prevented oxidation in non-irradiated and gamma-irradiated fish model system. Both extracts inhibited the growth of gram-positive (Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Geobacillus stearothermophilus) and gram-negative bacteria (Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella Enteritidis, Salmonella Typhimurium, Escherichia coli). Regardless of the strain, phenolic acid-rich extracts showed the lowest minimum inhibitory capacity (MIC); therefore presenting higher antibacterial effect. The MIC of phenolic acid-rich extracts (24–49μgphenolics/mL) was higher but comparable to Ampicillin (10μg/mL). Thus, phenolics in PS and MDBP may serve as antioxidants and antimicrobial compounds.
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