Autoxidation Of Linoleic Acid Research Articles

Formation of Lipid-Derived Flavors in Dry-Cured Mackerel (Scomberomorus niphonius) via Simulation of Autoxidation and Lipoxygenase-Induced Fatty Acid Oxidation.

In this study, lipoxygenase (LOX) extracted from dry-cured mackerel was purified, resulting in a 4.1-fold purification factor with a specific activity of 493.60 U/min·g. LOX enzymatic properties were assessed, referring to its optimal storage time (1-2 days), temperature (30 °C), and pH value (7.0). The autoxidation and LOX-induced oxidation of palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:2n9c), linoleic acid (C18:2n6c), arachidonic acid (C20:4), EPA (C20:5), and DHA (C22:6n3) were simulated to explore the main metabolic pathways of key flavors in dry-cured mackerel. The results showed that the highest LOX activity was observed when arachidonic acid was used as a substrate. Aldehydes obtained from LOX-treated C18:1n9c and C18:2n6c oxidation, which are important precursors of flavors, were the most abundant. The key flavors in dry-cured mackerel were found in the oxidative products of C16:0, C18:0, C18:1n9c, C18:2n6c, and C20:4. Heptanaldehyde could be produced from autoxidation or LOX-induced oxidation of C18:0 and C18:1n9c, while nonal could be produced from C18:1n9c and C18:2n6c oxidation. Metabolic pathway analysis revealed that C18:1n9c, C18:2n6c, EPA, and DHA made great contributions to the overall flavor of dry-cured mackerel. This study may provide a relevant theoretical basis for the scientific control of the overall taste and flavor of dry-cured mackerel and further standardize its production.

Antiproliferative Fatty Acids Isolated from the Polypore Fungus Onnia tomentosa.

Onnia tomentosa is a widespread root rot pathogen frequently found in coniferous forests in North America. In this study, the potential medicinal properties of this wild polypore mushroom collected from north-central British Columbia, Canada, were investigated. The ethanol extract from O. tomentosa was found to exhibit strong antiproliferative activity. Liquid-liquid extraction and bioactivity-guided fractionation, together with HPLC-MS/MS and 1D/2D NMR analyses of the ethanol extract of O. tomentosa, led to the identification of eight known linoleic oxygenated fatty acids (1.1-1.4 and 2-5), together with linoleic (6) and oleic acids (7). The autoxidation of linoleic acid upon isolation from a natural source and compound 5 as an autoxidation product of linoleic acid are reported here for the first time. GC-FID analysis of O. tomentosa, Fomitopsis officinalis, Echinodontium tinctorium, and Albatrellus flettii revealed linoleic, oleic, palmitic, and stearic acids as the major fatty acids. This study further showed that fatty acids were the major antiproliferative constituents in the ethanol extract from O. tomentosa. Linoleic acid and oleic acid had IC50 values of 50.3 and 90.4 µM against human cervical cancer cells (HeLa), respectively. The results from this study have implications regarding the future exploration of O. tomentosa as a possible edible and/or medicinal mushroom. It is also recommended that necessary caution be taken when isolating unstable fatty acids from natural sources and in interpreting the results.

Low-molecular-weight peptides as related to antioxidant properties of chicken essence

Different antioxidant measurements, including the inhibition of linoleic acid autoxidation, scavenging effect on α,α-diphenyl-β-picrylhydrazyl free radical, reducing power, and chelating abilities of metal ions Cu2+ and Fe2+, showed that the extract of chicken essence possessed antioxidant activities. The antioxidant activity increased with increasing concentration. Chicken essence contained a considerable amount of free amino acids, of which taurine was the predominant compound. Low-molecular-weight peptides were also present in a large quantity. An extraordinary feature was that the product contained high levels of potent antioxidants, anserine and carnosine. Three antioxidant peptide fractions of chicken essence were separated by size exclusion chromatography. The peptide with molecular weight of approximately 1400 Da possessed the strongest antioxidant activity, followed by peptides with 900 and 500 Da. Two antioxidant peptides were further isolated and identified, and their amino acid sequences were His-Val-Thr-Glu-Glu and Pro-Val-Pro-Ala-Glu-Gly-Val, respectively.

Antioxidant activities of carnosine, anserine, some free amino acids and their combination

For the evaluation of antioxidant activities of dipeptides (carnosine, anserine), and free amino acids (histidine, 1-methylhistidine, taurine, glycine, alanine, β-alanine), four methods were used, including the analysis of the inhibition of linoleic acid autoxidation, scavenging effect on α,α-diphenyl-β-picrylhydrazyl free radical, reducing power, and chelating ability of Cu2+. Results showed that carnosine and anserine were antioxidants preventing lipid peroxidation in linoleic acid systems. They also possessed effective abilities as free radical scavengers, reducing agents, and copper ion chelators. The activities increased with increasing concentration. However, the constituent amino acids of dipeptides, β-alanine, histidine and 1-methylhistidine, were not as effective in inhibiting oxidation regardless of individual or combined usage. Taurine, glycine, alanine and β-alanine showed much weaker antioxidant activities than carnosine, anserine, histidine and 1-methylhistidine. No synergistic effects on antioxidation were found among compounds used in combination. The results suggested that histidine-containing compounds were related to antioxidation abilities, and the peptide linkage between β-alanine, histidine and 1-methylhistidine was involved in the antioxidant activities of carnosine and anserine.

Antioxidant activity of aqueous extract fractions of velvet antler (Census elaphus Linnaeus)

Velvet antler is believed to have body strengthening, immunomodulatory and anti-aging effects. It is used in Chinese commercial functional foods and nutraceuticals. The antioxidant activity of the aqueous extract of velvet antler (AEVA) from Cervus elaphus Linnaeus was evaluated with DPPH-radical scavenging, FRAP, Fe2+-chelating and inhibition of linoleic acid autoxidation assays. AEVA showed antioxidant activity in all four assays. After removal of protein from AEVA, the antioxidant activity was significantly elevated. A semi-preparative HPLC equipped with a C18 column was used for further separation of the non-protein components (AEVA-S). Identification of the most active fraction (AEVA-SII) of AEVA-S was accomplished by LC/MS, HPLC and UV/Vis analyses. The HPLC chromatogram showed five main peaks identified as nucleotides (3′-CMP, 2′-CMP, 3′-UMP and 2′-UMP) and hypoxanthine. Nucleotides in AEVA-SII exhibited no free-radical scavenging and ferric-reducing activity. Only UMP exhibited Fe2+-chelating activity which accounted for 34.75% of the total Fe2+-chelating activity of AEVA-SII. The results indicated that other unidentified components with antioxidant activity were present in AEVA-SII.

Antioxidant activities of the water-soluble fractions of glandless and glanded cottonseed protein

To promote application of cottonseed protein products in food industry, this work measured antioxidant activities of two water soluble protein samples (Gl-L and Gd-L) isolated in a lab scale from glandless and common glanded cottonseed meal, respectively, and one soluble protein samples (Gd-P) in a pilot scale from glanded cottonseed meal. SDS-gel electrophoresis showed that the distribution patterns of the peptide fragments in Gl-L and Gd-L were similar, but more fragments and higher molecular mass bands were observed in the Gd-P gel image. While Gd-P showed the highest activities, Gl-L and Gd-L exhibited comparable 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical-scavenging activities in most cases. In contrast, Gd-P showed lower capability of inhibition of linoleic acid autoxidation than Gl-L and Gd-L. It would be of great interest in further research on these protein fractions in food products and processes (such as roasting) involved in the protective effects of food spoilage.

Effect of Sterilization Process and Storage on the Antioxidative Properties of Runner Bean.

In this study, we investigated the effect of standard preservation of bean seeds on changes in contents and activity of their selected components: dry matter, ash, different forms of nitrogen, composition of protein fractions; total phenolics and condensed tannins; ability to chelate iron(II) ions; antiradical activity against ABTS•+ and DPPH•; and capability for inhibiting autoxidation and enzymatic oxidation of linoleic acid. The conducted technological process caused various changes in contents of nitrogen forms and partial loss of phenolic compounds. The antiradical and antioxidative activity of the extracts decreased significantly, while an increase was observed in their ability to chelate Fe(II). These changes were due to the migration of active compounds to the brine, and to their structural transformations and degradation. Longer storage of the sterilized product caused restoration of part of the antiradical activity of the seeds.

Anti- and Pro-Oxidative Effect of α-Eleostearic Acid on the Autoxidation of Linoleic Acid

Anti- and Pro-Oxidative Effect of α-Eleostearic Acid on the Autoxidation of Linoleic Acid

Anti- and Pro-Oxidative Effect of α-Eleostearic Acid on the Autoxidation of Linoleic Acid

In this study, fatty acid composition of tung oil and the remaining fatty acid contents after oxidation were determined.Moreover, the oxidative stability of α-ESA was compared with linoleic acid (LA), linolenic acid (LnA), ara�chidonicacid (AA) and ecosapentaenoic acid (EPA) during auto-oxidation in the dark at 40°C. The results indicated that α-ESA content of tung oil was 79.45%. It was observed that the contents of remaining α-ESA, LA, LnA, AA and EPA after 24 h. were 0, 72.7, 53, 13 and 8.2%, respectively. Comparison between conjugated and non-conjugated fatty acids with the same number of double bonds showed that the conjugated fatty acid (CFA) declined more rapidly and fatty acid with more double bonds also degraded faster. The hydroperoxide content at 0.1, 0.2, 1 and 5% of α-ESA were 673, 762, 828 and 916 mM at 8 days and 40°C, respectively. Meanwhile, the peroxide content of methyl linoleate without α-ESA (control) was 563 mM at 8 days and 40°C.

Profiling of anthocyanins in transgenic purple-fleshed sweet potatoes by HPLC-MS/MS.

Anthocyanins in purple-fleshed sweet potato (PSP) are beneficial to human health. The leaf color (Lc) gene is a transcription factor involved in regulating anthocyanin biosynthesis. The anthocyanin profiles of wild-type PSP of Ayamurasaki and its three Lc-transgenic lines were investigated by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). In vitro antioxidant activities of wild-type and Lc-transgenic lines, including reducing power activity, DPPH radical scavenging activity, hydroxyl radical scavenging activity, linoleic acid autoxidation inhibition activity, ABTS free radical scavenging activity and oxygen radical absorbance capacity activity, were measured. The results showed that the total anthocyanin contents increased 1.5-1.9 times in three transgenic lines compared with that in wild-type PSP. Seventeen anthocyanins were found in wild-type PSP, while 19 in Lc-transgenic lines including cyanidin-based, peonidin-based and pelargonidin-based anthocyanins. Three pelargonidin-based anthocyanins were detected in three Lc-transgenic lines. Among them, the relative contents of cyanidin-based and pelargonidin-based anthocyanins increased 1.9-2.0 and 3.4-4.5 times respectively, while peonidin-based anthocyanins decreased 1.8-1.9 times in Lc-transgenic lines, compared with wild-type PSP. PSP from wild-type Ayamurasaki and three Lc-transgenic lines exhibited potent antioxidant activities, whereas there was no distinct difference among them. The transgene Lc significantly increased the content of total anthocyanins and remarkably changed the anthocyanin profiles in Ayamurasaki. Such novel and high content of anthocyanins obtained in the Lc-transgenic lines with potent antioxidant activities may provide unique functional products with potential helpful for human health. © 2017 Society of Chemical Industry.

Effect of ultrasonic pretreatment on the antioxidant properties of porcine liver protein hydrolysates

SummaryIn this study, the effect of ultrasonic pretreatment on the antioxidant activity of porcine liver protein hydrolysates (PLPHs) was investigated. The results showed that the degree of hydrolysis (DH) and peptide contents of the PLPHs increased as the time of ultrasonication increased. The hydrolysate pretreated with ultrasonication for 60 s exhibited the highest DH and peptide contents. The hydrolysate pretreated with ultrasonication for 45 s exhibited the highest ferrous ion chelating ability and reducing power. The hydrolysate pretreated with ultrasonication for 30 s exhibited the highest 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity and the higher inhibitory activity in the linoleic acid autoxidation system. The molecular weight of peptides in the hydrolysates was less than 6.2 kDa. The results clearly demonstrated that ultrasonic pretreatment enhances the antioxidant activities of the PLPHs in a short period of time (15–30 s).

감마오리자놀 함유 칼슘-펙틴 미세 및 나노캡슐의 제조와 입자 크기에 따른 캡슐특성

감마오리자놀의 산화안정성을 증진시키기 위해 천연 다당류인 펙틴과 칼슘이온의 이온결합을 이용한 펙틴 겔 미세캡슐과 나노캡슐을 제조하였다. 캡슐의 입자특성은 펙틴, 염화칼슘, 감마오리자놀 농도와 경화시간 변화에 영향을 받았으며, 포집 효율과 방출 조절 측면에서 가장 효과적이었던 펙틴 2%, 염화칼슘 4%, 경화시간 60분에서 제조한 미세캡슐과 펙틴 0.05%, 염화칼슘 4%, 감마오리자놀 5%에서 제조한 나노캡슐을 선정하였다. 입자 크기에 따른 두 캡슐 제형에 대한 비교분석 결과, 감마오리자놀 포집 효율은 입자 크기 증가로 인한 내부 포집공간 증가로 미세캡슐에서 더 높게 나타났으며, 이는 유효량 섭취의 효율측면에서 경구투여에 적합한 것으로 판단되었다. 감마오리자놀 함유 펙틴 캡슐 모두가 산성에서 방출이 억제되고 중성으로 갈수록 방출이 촉진되어 체내 소화환경에서 효과적인 전달체의 특성을 보였으며, 미세캡슐에 비해 나노캡슐의 방출 조절이 더 효과적으로 나타나 감마오리자놀의 장기 저장과 활성유지에 더 적합한 것으로 판단되었다. FTC법을 통한 지질산화 저해능 평가에서는 저장 5일 이후 유리 감마오리자놀의 산화방지 활성이 감소한 데 반해 감마오리자놀 함유 미세와 나노캡슐은 지속적인 지방산화 억제활성을 지속적으로 유지하였다. 본 연구를 통해 미세와 나노캡슐화는 감마오리자놀의 안정성 및 지질산화 활성 증대에 효과적이며, 제형 특성에 따라 다양한 용도로 활용 될 수 있을 것으로 판단된다. <TEX>${\gamma}-Oryzanol-loaded$</TEX> calcium-pectin micro- and nanocapsules were prepared by ionic gelation to improve oxidation stability and the effect of particle size on capsule properties was investigated. The physical properties were influenced by preparation conditions such as concentrations of pectin, <TEX>$CaCl_2$</TEX>, <TEX>${\gamma}-oryzanol$</TEX>, and hardening time. Particle sizes of micro- and nanocapsules that showed the maximum encapsulation efficiency and sustained release were <TEX>$2.27{\pm}0.02mm$</TEX> and <TEX>$347.7{\pm}58.1nm$</TEX>, respectively. Microcapsules showed higher encapsulation efficiency (<TEX>$50.73{\pm}1.98%$</TEX>) than nanocapsules (<TEX>$17.70{\pm}2.04%$</TEX>), while nanocapsules showed more sustained release and higher stability than microcapsules. Release of <TEX>${\gamma}-oryzanol$</TEX> from both microand nanocapsules, which was low in gastric environments and promoted in intestinal environments, showed suitable characteristics for oral administration. Furthermore, antioxidant activity of <TEX>${\gamma}-oryzanol$</TEX> against autoxidation of linoleic acid was prolonged by both micro- and nanoencapsulation in a ferric thiocyanate test. Therefore, micro- and nanoencapsulation using pectin can be effective for improving biodelivery, stability, and antioxidant activity of <TEX>${\gamma}-oryzanol$</TEX>.

Improving the antioxidant properties of quinoa flour through fermentation with selected autochthonous lactic acid bacteria

Lactic acid bacteria strains, previously isolated from the same matrix, were used to ferment quinoa flour aiming at exploiting the antioxidant potential. As in vitro determined on DPPH and ABTS radicals, the scavenging activity of water/salt-soluble extracts (WSE) from fermented doughs was significantly (P<0.05) higher than that of non-inoculated doughs. The highest inhibition of linoleic acid autoxidation was found for the quinoa dough fermented with Lactobacillus plantarum T0A10. The corresponding WSE was subjected to Reverse Phase Fast Protein Liquid Chromatography, and 32 fractions were collected and subjected to in vitro assays. The most active fraction was resistant to further hydrolysis by digestive enzymes. Five peptides, having sizes from 5 to 9 amino acid residues, were identified by nano-Liquid Chromatography-Electrospray Ionisation-Mass Spectra/Mass Spectra. The sequences shared compositional features which are typical of antioxidant peptides. As shown by determining cell viability and radical scavenging activity (MTT and DCFH-DA assays, respectively), the purified fraction showed antioxidant activity on human keratinocytes NCTC 2544 artificially subjected to oxidative stress.This study demonstrated the capacity of autochthonous lactic acid bacteria to release peptides with antioxidant activity through proteolysis of native quinoa proteins. Fermentation of the quinoa flour with a selected starter might be considered suitable for novel applications as functional food ingredient, dietary supplement or pharmaceutical preparations.

리놀레인산 자동산화에 미치는 페놀계 산화방지제의 활성 및 잔존량 평가

This study assessed the antioxidant activity and residue level of phenolic antioxidants in autoxidation of linoleic acid. The antioxidant activity of phenolic antioxidants was measured based on peroxide value of linoleic acid at 50°C for 8 days. We further evaluated the residue level of phenolic antioxidants in the autoxidation period by HPLC-UV. The residue level of antioxidants changed with time starting on day 0 (100%) and was determined by 100-remaining of antioxidants (%). Our results showed that peroxide values ranged from 0.33 to 10.18 meq/kg in propyl gallate, from 0.67 to 11.01 meq/kg in dodecyl gallate, from 0.01 to 10.34 meq/kg in octyl gallate, from 0.01 to 4.17 meq/kg in butylated hydroxytoluene (BHT), from 1.00 to 5.85 meq/kg in butylated hydroxyanisole (BHA), from 0.33 to 4.18 meq/kg in 2,4,5-trihydroxybutyrophenone, and from 1.00 to 11.01 meq/kg in tert-butylhydroquinone (TBHQ). Among the residue levels of antioxidants, on day 8, BHT showed the highest level while TBHQ showed the lowest. BHT showed the highest correlation coefficient, whereas BHA showed the lowest. This study proves that the residual level of phenolic antioxidants has a good correlation with the degree of autoxidation in linoleic acid.

Sequence Determination of an Antioxidant Peptide Obtained by Enzymatic Hydrolysis of Oyster Crassostrea madrasensis (Preston)

Soft tissue from cultured farm fresh oysters (Crassostrea madrasensis) was subjected to two standard enzymatic peptide extraction procedures using pepsin and papain. The crude extracts obtained were partially purified by column chromatography and were freeze-dried. The hydrolysates obtained were compared with respect to their degree of hydrolysis (DH), antioxidant potential (AP) and total phenolic content (TPC). The hydrolysate showing better antioxidant property was further subjected to purification by high performance liquid chromatography and characterized by LC-MS/MS. Papain-digested oyster protein (OPHpap) hydrolysate showed higher DH, AP and TPC. OPHpap was further subjected to ultrafiltration and fractionated into 3 sizes namely, above 10, 3–10 and 1–3 kDa according to the molecular size. Antioxidant capacity of <3 kDa fraction OPHpap-3 evaluated by DPPH free radical scavenging assay, metal chelating activity, linoleic acid autoxidation assay showed maximum effectiveness. Of the seven fractions collected by purification of OPH-pap-3 on semi-preparative RP-HPLC, fraction 7 that showed the highest antioxidant activity was further characterized by LC-ESI-MS/MS and its sequence determined. An antioxidant peptide molecule with thirteen amino acids was identified in oyster protein hydrolysate obtained by papain digestion that may find application as a nutraceutical or may be utilized in food industry for prevention of rancidity in foods.

Molecular hydrogen regulates gene expression by modifying the free radical chain reaction-dependent generation of oxidized phospholipid mediators.

We previously showed that H2 acts as a novel antioxidant to protect cells against oxidative stress. Subsequently, numerous studies have indicated the potential applications of H2 in therapeutic and preventive medicine. Moreover, H2 regulates various signal transduction pathways and the expression of many genes. However, the primary targets of H2 in the signal transduction pathways are unknown. Here, we attempted to determine how H2 regulates gene expression. In a pure chemical system, H2 gas (approximately 1%, v/v) suppressed the autoxidation of linoleic acid that proceeds by a free radical chain reaction, and pure 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine (PAPC), one of the major phospholipids, was autoxidized in the presence or absence of H2. H2 modified the chemical production of the autoxidized phospholipid species in the cell-free system. Exposure of cultured cells to the H2-dependently autoxidized phospholipid species reduced Ca2+ signal transduction and mediated the expression of various genes as revealed by comprehensive microarray analysis. In the cultured cells, H2 suppressed free radical chain reaction-dependent peroxidation and recovered the increased cellular Ca2+, resulting in the regulation of Ca2+-dependent gene expression. Thus, H2 might regulate gene expression via the Ca2+ signal transduction pathway by modifying the free radical-dependent generation of oxidized phospholipid mediators.

Preparation, separation and antioxidant properties of hydrolysates derived from Grifola frondosa protein

Dong Y., Qi G., Yang Z., Wang H., Wang S., Chen G. (2015): Preparation, separation and antioxidant properties of hydrolysates derived from Grifola frondosa protein. Czech J. Food Sci., 33: 500–506. In order to take full advantage of Grifola frondosa resources, the protein (GFP) was extracted from G. frondosa fruiting body and digested using six different proteases (papain, neutrase, alcalase, trypsin, pepsin, and Protamex) to produce the antioxidative hydrolysates. The trypsin hydrolysate prepared at 1.5 h possessed the strongest antioxidant potential among different hydrolysates, which was separated into four major fractions by ultrafiltration membranes with differ ent molecular weight cut-off (MWCO), that are GFHT-1 ( MW > 10 kDa), GFHT-2 (MW = 5–10 kDa), GFHT-3 ( MW = 3–5 kDa), and GFHT-4 (MW < 3 kDa). In succession, the in vitro antioxidant activities of the four fractions were further evaluated, including the scavenging effect on DPPH, ferrous ion chelating effect, reducing power, and ability to inhibit the autoxidation of linoleic acid. The results demonstrated that all fractions are effective antioxidants and comparably GFHT-4 has the highest antioxidant activity. Then GFHT-4 was separated to two major peptide fractions by gel filtration chromatography, and the two fractions were located at 2385 Da (F-1) and 1138 Da (F-2), respectively.

The Claim of Anti-Cataract Potential of Heliotropium indicum: A Myth or Reality?

Introduction Heliotropium indicum has several uses in traditional medicine attributable to its numerous bioactive compounds. It is used as a traditional remedy for cataracts in Ghana without any scientific verification. This study aimed at verifying the anti-cataract properties of an aqueous whole plant extract of H. indicum.MethodsThe effect (cataract score) of 30, 100, and 300 mg kg−1 extract (bid for 21 days, per os) on the development of 30 µmol kg−1 sodium selenite-induced cataract in 10-day-old rat pups was investigated. Soluble lens proteins alpha A and alpha B crystallins, total lens protein, total lens glutathione, and aquaporin 0 in enucleated lens homogenates were determined spectrophotometrically using commercially available kits. Histopathological studies on the lenses were also performed. The 2,2-diphenyl-1-picrylhydrazyl scavenging effect and linoleic acid autoxidation (antioxidant properties) of the extract (0.1–3.0 mg ml−1), compared to n-propyl gallate, were ascertained using standard procedures.ResultsCataract scores showed that the extract, at all dose levels, significantly alleviated selenite-induced cataracts (P ≤ 0.001). Markers of lens transparency (aquaporin 0, alpha A and B crystallins), as well as total lens proteins and lens glutathione levels, were significantly preserved (P ≤ 0.01–0.001). The extract exhibited activity relevant for scavenging free radicals and inhibition of lipid peroxidation. Epithelial and lens fiber integrity in the histopathological assessment were maintained with HIE treatment.ConclusionThe aqueous whole plant extract of H. indicum significantly inhibited the development of cataracts in rats via multiple mechanisms.

Total phenolic content and antioxidant activities of pomegranate juice and whey based novel beverage fermented by kefir grains.

Mixture of pomegranate juice and whey was evaluated as a potential substrate for production of a novel beverage by kefir grains. The effects of two different variables, fermentation, temperature (19 and 25°C) and kefir grain amount (5%w/v and 8%w/v), on total phenolic content (TPC) and antioxidant activities of beverage were examined during a fermentation time of 32h. TPC and antioxidant activities including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, inhibition effect upon linoleic acid autoxidation and inhibition effect upon ascorbate autoxidation increased significantly (p < 0.05) during fermentation, but metal chelating effect showed no significant difference. The highest increases were observed when the temperature of 25°C and kefir grain amount of 8%w/v were applied. Results proved antioxidant activities of beverages were desirable and fermentation by kefir grains has the ability to enhance these antioxidant activities, as compared with unfermented beverage. Also pomegranate juice and whey were suitable media for producing a novel dairy-juice beverage.

Synergistic actions of proteolytic enzymes for production of soy protein hydrolysates with antioxidant activities: An approach based on enzymes specificities

Abstract The objective of this study was to investigate the enzymatic hydrolysis of soy protein isolate by screening individual and blended commercial protease preparations using a statistical mixture design. Information about the modulation of thermal inactivation of the enzyme by substrate or products of hydrolysis and the determination of synergistic effects between the enzymes on production of soy protein hydrolysates with antioxidant activities were reported. The kinetic parameters for thermal inactivation measured under reactive and non-reactive conditions indicated that product inhibition was not significant on soy protein hydrolysis using the commercial proteases Flavourzyme® 500 L, Alcalase® 2.4 L and YeastMax A. For DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, the hydrolysates obtained with Flavourzyme® 500 L combined with Alcalase® 2.4 L showed the higher synergistic effect with increases of 10.9% and 13.2% in antioxidant activity as compared to the hydrolysates produced with individual enzymes. The hydrolysates obtained using the ternary mixtures of Flavourzyme® 500 L, Alcalase® 2.4 L and YeastMax A showed the highest power of inhibition of linoleic acid autoxidation. On the other hand, for reducing power assay and total antioxidant activity, the most of all interactions was antagonistic with high antioxidant activity detected for the hydrolysates produced using Flavourzyme® 500 L, individually.