•Casein hydrolysate <1 kDa by alcalase had higher antioxidant activity than trypsin.•Casein hydrolysate with high ABTS ability consisted mainly of Arg, Leu, Ala, Ser.•Buffalo casein hydrolysate contained antioxidant peptides RELEE, MEDNKQ, TVA, EQL.•Bovine casein hydrolysate contained antioxidant peptides PYPQ, EMPFPK, YFYPE, PQSV.•Mechanism and reaction pathways of RELEE, TVA and EQL with ABTS were proposed.Buffalo and bovine caseins were hydrolysed by alcalase and trypsin to produce novel antioxidant peptides. The casein hydrolysates were purified using ultrafiltration (UF) and further characterized by RP-HPLC. The fractions produced higher antioxidant activities were identified for their peptides using LC MS/MS. All UF-VI (MW < 1 kDa) fractions showed higher antioxidant activity. Hydrolysate produced by alcalase for buffalo casein (UF-VI with 54.84-fold purification) showed higher antioxidant activity than that obtained by trypsin. Trypsin hydrolysate contained high amount of hydrophobic amino acids while alcalase hydrolysate consisted mainly of Ser, Arg, Ala and Leu. The antioxidant peptides identified by LC MS/MS were RELEE, MEDNKQ and TVA, EQL in buffalo casein hydrolysates produced by trypsin and alcalase, respectively. Mechanism and reaction pathways of selected antioxidant peptides with ABTS were proposed. Conclusively, buffalo casein provided antioxidant peptides similar to bovine, suggesting that buffalo casein is a novel source of antioxidant.

•α-, β-casein bound with MG mainly via hydrophilic or hydrophobic interactions.•α-Casein had a slightly stronger binding affinity toward MG than β-casein.•MG binding caused different alterations of the secondary structure of α-, β-casein.•Casein–MG interaction had a positive effect on the stability of GSAE.The interactions of α- and β-casein with malvidin-3-O-glucoside (MG), the major anthocyanin in grape skin anthocyanin extracts (GSAE), were examined at pH 6.3 by fluorescence, fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy. The binding constant (KS), binding force and effects of the interactions on the caseins conformation and GSAE stability were investigated. The results showed that α- and β-casein bound with MG via hydrophilic (van der Waals forces or hydrogen bonding) and hydrophobic interactions, respectively. α-Casein had a slightly stronger binding affinity toward MG than β-casein, with respective KS values of 0.51 × 103 M−1 and 0.46 × 103 M−1 at 297 K. The secondary structures of α- and β-casein were changed by MG binding, with a decrease in α-helix and an increase in turn for α-casein and no change in α-helix and a decrease in turn for β-casein. The casein–anthocyanin interaction appeared to have a positive effect on the thermal, oxidation and photo stability of GSAE.

•Chemical component of T. grandis kernels vary to different extent with cultivars.•T. grandis oil is rich in UFA including linoleic, oleic and eicosatrienoic acid.•T. grandis oil contains abundant β-, γ-tocopherols, β-sitosterol and polyphenols.•T. grandis oil is a potential source of edible oil or functional ingredient.The chemical compositions of cold pressed kernel oils of seven Torreya grandis cultivars from China were analyzed in this study. The contents of the chemical components of T. grandis kernels and kernel oils varied to different extents with the cultivar. The T. grandis kernels contained relatively high oil and protein content (45.80–53.16% and 10.34–14.29%, respectively). The kernel oils were rich in unsaturated fatty acids including linoleic (39.39–47.77%), oleic (30.47–37.54%) and eicosatrienoic acid (6.78–8.37%). The kernel oils contained some abundant bioactive substances such as tocopherols (0.64–1.77 mg/g) consisting of α-, β-, γ- and δ-isomers; sterols including β-sitosterol (0.90–1.29 mg/g), campesterol (0.06–0.32 mg/g) and stigmasterol (0.04–0.18 mg/g) in addition to polyphenols (9.22–22.16 μg GAE/g). The results revealed that the T. grandis kernel oils possessed the potentially important nutrition and health benefits and could be used as oils in the human diet or functional ingredients in the food industry.

•β-Lactoglobulin bound with MG mainly via hydrophobic interaction.•The secondary structure of β-lactoglobulin was changed by MG binding.•Whey protein prevented the color fading and anthocyanin degradation of GSAE.•β-Lactoglobulin–MG interaction had a positive effect on the GSAE stability.The binding interaction between bovine β-lactoglobulin and malvidin-3-O-glucoside (MG), the major anthocyanin in grape skin anthocyanin extracts (GSAE), was studied at pH 6.3 using fluorescence, Fourier transform infrared and circular dichroism spectroscopy. The binding constant (KS), binding force and effect of the interaction on the β-lactoglobulin conformation and GSAE stability were investigated. The results indicated that β-lactoglobulin complexed with MG mainly via hydrophobic interaction with KS of 0.67 × 103 M−1 at 297 K. The secondary structure of β-lactoglobulin was changed by MG binding, with a decrease in α-helix, turn and random coil and an increase in β-sheet. Bovine whey protein effectively prevented the color fading and degradation of anthocyanin in the GSAE solution during the thermal treatment (80 °C/2 h), H2O2 oxidation (0.005% H2O2/1 h) and photo illumination (5000 lx/5 d). The whey protein-anthocyanin complexation appeared to have a positive effect on the thermal, oxidation and photo stability of GSAE.

The identification and quantitation of the anthocyanins in 12 purple-fleshed sweet potato (PFSP) cultivars (‘Jihei 1’, ‘Xuzi 3’, ‘Xuzi 6’, ‘Zhezi 4’, ‘Ningzi 1’, ‘Ningzi 2’, ‘Ningzi 3’, ‘Ning 2-2’, ‘Ning 6-8’, ‘Guangzi 1’, ‘Ziluolan’, and ‘Qinzi 1’) in China were carried out using a combination of ultraperformance liquid chromatography–photodiode array (UPLC-PDA), quadrupole-time-of-flight mass spectrometry (QTOF-MS), and tandem mass spectrometry (MS/MS) analyses. Thirteen acylated anthocyanins were tentatively characterized, including two new PFSP anthocyanins, cyanidin 3-caffeoyl-vanilloyl sophoroside-5-glucoside and peonidin 3-caffeoyl-vanilloyl sophoroside-5-glucoside. The quantitative analyses of these anthocyanins were conducted using cyanidin 3-O-glucoside as a standard. The total anthocyanin content of the PFSPs depended on the cultivar. The five PFSP cultivars with the highest content of anthocyanins were ‘Jihei 1’, ‘Xuzi 3’, ‘Zhezi 4’, ‘Ziluolan’, and ‘Qinzi 1’. This is the first report of the ‘Ningzi 2’, ‘Ningzi 3’, and ‘Ning 2-2’ PFSP cultivars containing only diacylated anthocyanins and of the ‘Xuzi 6’ cultivar containing single anthocyanidin-based anthocyanins.

•Antioxidant capacity of FJMB little affected by pH adjustment and pasteurization.•WP had none, masking or synergetic effects on the ABTS and FRAP of FJMB.•Sterilization could significantly increase or decrease the ABTS and FRAP of FJMB.•WP digestion of FJMB was inhibited by CHA and CAT to varying degrees.•Sterilization accelerated WP digestion but did not change its overall digestibility.The effects of simulated processing (pH adjustment and thermal treatment) on the antioxidant capacity and in vitro protein digestion of fruit juice-milk beverage (FJMB) models consisting of whey protein (WP), and chlorogenic acid (CHA) or catechin (CAT) were investigated. Results indicated that CAT was more susceptible to processing than CHA, and showed a significant (p < 0.05) decrease in ABTS and FRAP after sterilization (121 °C/10 min) and pH adjustment to 6.8. WP addition had different effects (none, masking, synergetic effect) on the antioxidant activity of FJMB. Pasteurization (63 °C/30 min) and pH adjustment (pH 3.7 or pH 6.8) had either non-significant or slight effects on FJMB’s antioxidant capacity, while sterilization significantly (p < 0.05) increased or decreased its ABTS and FRAP depending on the different models. In vitro digestion of WP in FJMB was obviously (p < 0.05) inhibited by phenolics to varying degrees, and little influenced (p > 0.05) by pasteurization, whereas sterilization initially accelerated WP digestion but did not change its overall digestibility.

The binding interactions between (−)-epigallocatechin-3-gallate (EGCG) and bovine β-lactoglobulin (β-LG) during food processing under different temperatures (25–100 °C) and pH levels (3.2–7.4) were investigated using the fluorescence quenching method. The results indicated that temperature and pH had different effects on the structure and EGCG-binding ability of β-LG. At a higher pH (≥6.4) and temperature (≥80 °C), the structure and conformation of β-LG were more open than those of its native state due to the heat-induced denaturation and unfolding of protein, which increased its binding affinity with EGCG through hydrophobic interactions and hydrogen bonds, which in turn promoted its further unfolding. The highest binding constant (KA) and the binding site numbers (n) were 12.50 (±0.60) × 105 M−1 (pH 6.4, 80 °C), and 0.62 (±0.02)~0.97 (±0.16), respectively. However, at 100 °C and a neutral pH, the oxidative loss of EGCG during thermal processing probably led to a decrease in β-LG–EGCG interactions. These results would be helpful to better understand the relevance of the β-LG–EGCG interaction to the bioactivity and bioavailability of EGCG during food processing, and to maintain the health benefits of this type of functional products in the food industry.

•Physicochemical and functional properties of T. grandis proteins were investigated.•Two cultivars of seed proteins were compared while they had similar composition.•T. grandis protein fractions were mostly about 31–37 kDa and 20–21 kDa.•Proteins showed high denatured temperature and good solubility.•Both proteins had favourable emulsifying and foaming and fat absorption capacities.Proteins extracted from Torreya grandis seeds were investigated for their physicochemical and functional properties. The results showed protein extracts from two cultivars of T. grandis, Shengzhou I (SZPI) and Dazinaiyou (DNPI), had similar protein contents and appropriate amino acid balances with about 41% of the essential amino acid. The molecular weights of seed protein fractions were mostly about 31–37 kDa and 20–21 kDa. SZPI and DNPI had similar denaturation temperature of around 93.7 °C while free sulfhydryl group and disulfide bond contents were found to differ slightly. The surface hydrophobicity of DNPI was 982, significantly (p < 0.05) greater than that of SZPI (649). Both proteins exhibited high solubilities and favourable emulsifying abilities, foaming and fat absorption capacities, although their in-vitro digestibilities were rather low. Therefore, T. grandis seed proteins have potential as valuable nutrition sources and functional ingredients in food industry.

•The release of flavor compounds was restrained in SPI and/or xanthan gum solution.•Xanthan gum evidently changed the retention of (Z)-3-hexen-1-ol, limonene and diacetyl.•Other esters promoted flavor ester release in SPI-xanthan gum mixture solution.•Less-volatiles accelerated ester release to some extent in different matrices.The effects of xanthan gum on the release of strawberry flavor compounds in formulated soy protein isolate (SPI) beverage were investigated by headspace gas chromatography (GC). Seven strawberry flavor compounds (limonene, ethyl hexanoate, (Z)-3-hexenyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, (Z)-3-hexen-1-ol and diacetyl) could be detected by GC and hence analyzed the gas-matrix partition coefficients (K). The release of flavor compounds was restrained in SPI and/or xanthan gum solution. The retention of (Z)-3-hexen-1-ol, limonene and diacetyl significantly changed (p < 0.05) with increasing xanthan gum concentrations. Presence of any other esters led to suppression of the release of ester compounds in water and SPI solution. The less-volatiles (γ-decalactone, methyl cinnamate, hexanoic acid, 2-methyl butyric acid and furaneol) accelerated the release of ester compounds to some extent in different matrices. The above results demonstrated that presence of SPI and xanthan gum could bring about an imbalance in the strawberry flavor.