A differential scanning calorimetry (DSC) method was used to investigate the denaturation temperature of yak α-lactalbumin (α-La), β-lactoglobulin (β-Lg), and a mixture of two proteins and the thermal properties of α-La and β-Lg in the presence of glucose, lactose, sucrose, NaCl, CaCl2, and at various pH (4.0–10.0). The denaturation temperature (Td) of α-La increased from 52.1 °C in the absence of β-Lg to 53.9 °C in the presence of β-Lg, while the Td of β-Lg decreased from 81.4 °C in the absence of α-La to 79.9 °C in the presence of α-La. α-La was thermal stable in the range of pH 4.0–10.0, while β-Lg was more thermal stable in acidic pH than in alkaline pH. Sugars, Na+, and Ca2+ influenced the stabilization of the two proteins against thermal denaturation with greatly influenced for β-Lg. α-La kept reversibility in the presence of sugars, NaCl, CaCl2, and over a wide pH range (4.0–10.0), with most of the reversibility values being greater than 90%. In contrast, β-Lg was completely irreversible whether in its native state or in the presence of the additives.

A novel method to improve the proliferation activity of C2C12 cells by the bovine milk fat globule membrane (MFGM) protein was established in this study. The MFGM protein was extracted and isolated into 4 fractions using an electric cream separator, and purified by a cellulose DEAE-52 column. Fraction 2 accounted for 57.8% of the total MFGM protein, and was used in the following study. The MTT assay showed that it induced cell proliferation activity, increased the cell survival rate and the cell number using flow cytometry and fluorescence microscopy analysis. There were only subtle changes in the morphology as observed using confocal scanning laser microscopy, but the number of mitochondria was significantly increased as observed using transmission electron microscopy analysis. Furthermore, the mRNA expression of MyoD, cyclin D1, p70S6K and mTOR was up-regulated as determined utilizing the quantitative real-time PCR assay, and the activation of Akt and mTOR phosphorylation was up regulated as determined using the Western blot assay. The main protein in fraction 2, assayed by 1-D gel electrophoresis and MALDI TOF-TOF, was identified as milk fat globule-EGF factor 8, the content was 65.6% of the total protein in fraction 2. The results elucidate a new molecular mechanism of the MFGM protein fraction 2: the activation of the Akt signal pathway in promoting cell proliferation.

Milk fat globule-EGF factor 8 (MFG-E8) protein can promote growth factor induced survival and proliferation of vascular endothelial cells, leading to angiogenesis. Little has been reported on the potential effects of MFG-E8 on cell differentiation and the molecular mechanism. In this study, MFG-E8, the major component of milk fat globule membrane (MFGM) protein (82.35%), was isolated and purified using cellulose DEAE-52. Its effects on myogenic differentiation of murine skeletal muscle C2C12 cells were investigated using qRT-PCR, Western blotting and immunofluorescence assay. MFG-E8 promoted the formation of multinucleated myotubes, and increased the fusion index. In addition, Akt-activity was significantly increased during MFG-E8 induced C2C12 cell differentiation, whereas wortmannin, a PI3K inhibitor, was able to block the differentiation of C2C12 cells promoted by MFG-E8. MFG-E8 enhanced the expression of the myogenic regulatory factor MyHC in C2C12 cells over time. Conversely, the expression of MyHC was also inhibited by wortmannin. We conclude that MFG-E8 promotes the differentiation of C2C12 cells by activating the PI3K/Akt signaling pathway. Taken together, these results show that MFG-E8 could exert a beneficial effect on C2C12 myoblast cell differentiation, and therefore, it may have potential as a differentiation-inducing agent for the therapy of sarcopenia.

An efficient gas chromatographic method for the accurate analysis of fatty acid composition in milk was validated. This method provides an excellent resolution of almost 60 fatty acids from odd branched chain fatty acids (OBCFA), trans-monoenoic fatty acid to polyunsaturated fatty acids (PUFA) simultaneously. The quantitation limit was as low as 0.33~1.80 mg/100 g milk with a good intra-day (RSD 0.53~9.6%) and inter-day (RSD 1.25~9.1%) repeatability with an average recovery of 97.3%. This method was applied to determine the fatty acid composition in human, cow, buffalo, goat, yak, and camel milk. Human milk had the lowest amount of saturated fatty acids and highest amount of polyunsaturated fatty acids (31.7 ± 0.31 g/100 g total fatty acids). Yak milk contained the highest amount of C18:1 trans-11 (3.06 ± 0.03 g/100 g total fatty acids). Furthermore, the high proportion of butyric acid (12.2 ± 0.09 g/100 g total fatty acids), OBCFA (2.16 ± 0.02 g/100 g total fatty acids), α-linolenic acid (2.12 ± 0.02 g/100 g total fatty acids), and arachidonic acid (1.35 ± 0.02 g/100 g total fatty acids) were found in the milk from two-humped camel.

At the natural pH of yak milk (pH 6.6), a low level (<30%) of κ-casein (κ-CN) was found in the serum phase after heating at 95 °C for 30 min, indicating that as much as 70% of the β-lactoglobulin (β-Lg) and κ-CN complexes is associated with the micelle colloidal particles. The β-Lg and κ-CN levels increased from 13.2% and 2.6% at pH 6.0 to 35.2% and 60.1% at pH 7.0, respectively, when yak milk was heated at 95 °C for 30 min. At pH 6.0–6.4, the denatured whey proteins were associated with the caseins in the colloidal phase, resulting in milk gelation upon heating. The distribution of β-Lg and κ-CN complexes increased in the serum phase, demonstrated by the increasing levels of both β-Lg and κ-CN with increasing pH; at high pH (6.6–7.0), large proportions of β-Lg and α-lactalbumin were lost, presumably forming complexes in the colloidal phase.

•Lectin was extracted from black turtle bean by reverse micellar extraction.•Optimum condition for lectin extraction has been established.•The combined effects of processing parameters were studied using RSM.•The reliability of the method was confirmed by SDS–PAGE and RP-HPLC.•Conformational changes of the lectin were confirmed by FTIR method.Lectin from black turtle bean (Phaseolus vulgaris) was extracted and purified by reverse micellar extraction (RME) method. Response surface methodology (RSM) was used to optimise the processing parameters for both forward and backward extraction. Hemagglutinating activity analysis, SDS–PAGE, RP-HPLC and FTIR techniques were used to characterise the lectin. The optimum extraction conditions were determined as 77.59 mM NaCl, pH 5.65, AOT 127.44 mM sodium bis (2-ethylhexyl) sulfosuccinate (AOT) for the forward extraction; and 592.97 mM KCl, pH 8.01 for the backward extraction. The yield was 63.21 ± 2.35 mg protein/g bean meal with a purification factor of 8.81 ± 0.17. The efficiency of RME was confirmed by SDS–PAGE and RP-HPLC, respectively. FTIR analysis indicated there were no significant changes in the secondary protein structure. Comparison with conventional chromatographic method confirmed that the RME method could be used for the purification of lectin from the crude extract.

•Lectin of high purity (⩾94%) was obtained from black turtle bean.•In vitro digestibility of the protein was evaluated by SDS–PAGE gels.•A kinetic approach was employed to quantify the digestion of the protein.•The influence of preheating and metal ions on the protein was also studied.•UV and fluorescence spectra were applied to monitor the conformational changes.In this study, the in vitro digestibility of lectin from black turtle bean was investigated in simulated gastric fluid (SGF) and tryptic digestion, using kinetic densitometric analysis for SDS–PAGE and spectroscopic measurements. It was found that the native lectin was relatively stable in both SGF (half-life = 22.71 min) and tryptic digestion (half-life ⩾90 min), the susceptibility of the protein to hydrolysis by proteases was markedly increased by preheating and also enhanced by demetallization. An unfolding state of the preheated lectin was observed by UV and fluorescence spectroscopy, although the conformational changes were found to be limited by the demetallization. This study provides evidence that metal ions may provide resistance during protease hydrolysis, and suggests both preheating and demetallization contribute to in vitro proteolytic degradation of lectin.

A response surface methodology and a kinetic study were used to optimise the pulsed ultrasonic and microwave techniques in the extraction of curcuminoids. Microwave-assisted extraction had the same efficiency as pulsed ultrasonic-assisted extraction, and both methods were better than continuous ultrasonic extraction of curcuminoids. For the pulsed ultrasonic-assisted extraction, the optimal conditions were 60% amplitude (AMP), 83% ethanol (v/v), 3/1 (s/s) pulsed duration/interval time and 10 min irradiation time. For the microwave-assisted extraction, the optimal conditions were 82% ethanol, 10% power level and 7 min of extraction time. Both methods used a 1:200 mass to solvent ratio.

The compositional factors involved in the heat stable sensitivity of yak milk were investigated. Compared to heat-unstable yak milk, heat-stable yak milk samples were characterized by higher pH, non-protein-nitrogen, soluble proteins, whey protein, urea, P, a lower soluble Ca and ratio of Ca to P. The content of κ-casein in heat-stable yak milk is higher than in heat-unstable yak milk. The content of αs1-casein in heat-stable yak milk is lower than in heat-unstable yak milk. For whey proteins, the content of β-LGA and β-LGB in heat-stable yak milk is higher than in heat-unstable yak milk.

The aim of this study was to investigate diversity of the αS1-casein gene in Maiwa yak. A polymorphism of αS1-casein gene has been identified in Chinese Maiwa yak by PCR single-strand conformation polymorphism protocol. Comparing the X59856 sequence, some non-coding and coding DNA variants of yak CSN1S1 gene were detected in this present study, including KJ397913 (promoter region, 9969A/G, 9984 A/G, 10153 C/T, 10175 A/C, 10261 G/C), KJ397914 (promoter region 10261 G/C), KJ397896 (intron III, 14862 T/C), KJ397897 (intron III, 14862 T/C, and deleted 14944-14946 CTT), KJ397899 (intron IV, 15297 A/C), KJ397901 (intron VIII, 17503 A/C, 17666 A/C), KJ397902 (exon IX, 18901C/A, intron IX, 18970 T/G, 19088 add A, 19120 add A, 19202 add T, 19296 G/T), KJ397903 (intron IX, 18970 T/G, 19088 add A, 19120 add A, 19202 add T, 19296 G/T), KJ397904 (intron IX, 19537 T/G, 19539T/G, 19599G/A, 19638 C/T), KJ397905 (intron XIV, 23402 T/G, 23417 C/T, 23480 T/C, 23511 G/A), and KJ397907 (intron XVI, 25976 G/T; exon XVII, 26181A/G). The polymorphism of αS1-casein gene may be helpful for future studies on genetic variation within and between yak populations or on associated traits.

Highlights•A partial change of β-Lg structure occurs when CCM binds with it.•β-Lg interacts with CCM via hydrophobic interaction.•One molecule of protein combines with one molecule of CCM.•CCM binds respectively on the surface and central of β-Lg at pH 6.0 and 7.0.•The antioxidant activity of CCM might be improved by binding with β-Lg.The binding of curcumin (CCM) to bovine β-lactoglobulin (β-Lg) was investigated by Fourier transform infrared and fluorescence. The effect of binding on antioxidant activity of CCM was determined by using ABTS and hydroxyl radical scavenging capacity and total reducing ability. Our results showed that when CCM binds to β-Lg, it lead to a partial change in protein structure. In fact, CCM was bound respectively to two different sites of protein at pH 6.0 and 7.0 via hydrophobic interaction. CCM–β-Lg complex was formed by one molecule of protein combining with one molecule of CCM. Moreover, the average distance from one binding site to Trp residues in protein is similar with another. This result suggested that fluorescence resonance energy transfer cannot be used as unique method to study the characteristics of binding of ligands to proteins. The antioxidant activity of CCM might be improved by binding with β-Lg.

Lactic acid bacteria (LAB) from traditional Chinese fermented soybean paste were isolated and identified. A total of 61 LAB were selectively obtained from 32 homemade Chinese soybean pastes. The isolated LAB were divided into two groups by their salt tolerance, 28 halophilic LAB and 33 non-halophilic LAB. Phenotypic analysis showed that these LAB belonged to four genera and 13 species. Tetragenococcus halophilus was the predominant species in the identified strains. Four species of LAB were firstly isolated from fermented soybean food product, Lactobacillus panis, Lactobacillus pentosus, Lactobacillus vaccinostercus and Lactobacillus collinoides. T. halophilus T5 showed vigorous growth and fast acidification in high salt concentration. The volatile compounds of mixed microorganism soybean paste with T. halophilus T5, Zygosaccharomyces and Torulopsis candida, during the different fermentation stage were higher in number than those of normal soybean paste at same processing procedure.

The present study was undertaken to evaluate the fatty acid composition, conjugated linoleic acid (CLA) and cholesterol contents in the milk from three yak breeds, Maiwa yak (n = 24), Zhongdian yak (n = 16) and Gannan yak (n = 16) and two yak crossbreeds, Maiwa yak × yellow cattle (n = 16) and Gannan yak × yellow cattle (n = 16). Statistically significant differences (P < 0.05) in the proportions of individual milk fatty acids were observed among the three yak breeds. The proportion of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) did not differ statistically (P > 0.05) among the three yak breeds. However, the percentage of total polyunsaturated fatty acids (PUFAs) in Zhongdian yak milk (4.82%) was significantly higher (P < 0.01) than in Maiwa (3.99%) and Gannan (3.68%) yak milks. The contents of α-linolenic acid (C18:3) and cis-9, trans-11 conjugated linoleic acid (CLA) were significantly different (P < 0.05) among the three yak breeds. The total SFAs, MUFAs and PUFAs were not significantly different (P > 0.05%) between the two yak crossbreeds. The cholesterol contents in milk samples from yak breeds and yak crossbreeds were found to be in the range 12.32–16.17 mg/100 g. Cholesterol contents in milk samples from yak breeds and yak crossbreeds were positively correlated with their fat contents.

This is a comparison of potential allergenicity in a mouse model. Balb/C mice were sensitized by intraperitoneal injections (administered in three doses) of skimmed milk, casein, and whey protein from cow or yak milk. After 4 weeks, the mice were challenged and killed, sera were collected, and the spleens removed for analysis. An enzyme-linked immunosorbent assay was used to determine the specific antibodies (IgG and IgE) and cytokine. The number of mice with diarrhea was higher in the cow milk protein-sensitized group than in the yak milk protein-sensitized group. Serum (IgG, IgE) antibodies and histamine levels were also higher in cow milk protein-sensitized mice. Cytokine production by spleen-derived T cells showed high levels of interleukin-4 and interleukin-5 production and low levels of interferon-γ in cow milk protein and yak milk protein-sensitized mice. Lymphocyte proliferation ratio induced by yak milk protein was lower than cow milk protein. All results indicated that Maiwa yak milk protein may less allergenic than cow milk protein in mice.

Consumption of dairy products containing probiotics with cholesterol-lowering activity has been proposed as a means to lower serum cholesterol. In the present work, 19 yeast strains, isolated from raw milk, were tested to obtain potential probiotic yeasts for assimilating cholesterol. During in vitro tests, 17 yeast strains were capable of growth in bile salt solutions, and most of the yeast strains tolerated low pH, surviving in gastric juice. Among the 19 strains assessed, Geotrichum sp. BY2 and Pichia kudriavzevii BY10 showed highest adhesive ability to HT-29 cells. All yeast strains were able to assimilate cholesterol in the range of 3.6–44.4% over a 72 h incubation, and seven of the yeast strains were significantly higher at assimilating cholesterol (P < 0.05). According to these results, the yeast strains P.fermentans BY5, P. kudriavzevii BY10, P. kudriavzevii BY15 and Yarrowia lipolytica HY4 may serve as potential probiotics to assimilate cholesterol in the human intestine.La consommation de produits laitiers contenant des probiotiques ayant une activité hypo-cholestérolémiante a été proposée comme moyen d’abaisser le cholestérol sanguin. Dans la présente étude, 19 souches de levure isolées à partir de lait cru ont été testées comme probiotiques potentiels pour assimiler le cholestérol. Au cours des tests in vitro, 17 souches étaient capables de croissance dans des solutions de sels biliaires, et la plupart des souches tolérait bien les faibles pH, en survivant dans le jus gastrique. Parmi les 19 souches testées, Geotrichum sp. BY2 et Pichia kudriavzenii BY10 montraient la plus grande capacité d’adhésion aux cellules HT-29. Toutes les souches de levure étaient capables d’assimiler le cholestérol à hauteur de 3,6 à 44,4 % après une incubation de 72 h et 7 souches avaient des taux d’assimilation significativement plus élevés (P < 0,05). D’après ces résultats, les souches de levure Pichia fermentans BY5, P. kudriavzenii BY10, P. kudriavzenii BY15 et Yarrowia lipolytica HY4 pourraient être utilisées comme probiotiques potentiels pour assimiler le cholestérol au niveau de l’intestin chez l’Homme.19 17 pH 19 Geotrichum sp. BY2 Pichia kudriavzevii BY10 T-29 72 h 3.6 44.4% 7 (P < 0.05) P. fermentans BY5 P. kudriavzevii BY10 P. kudriavzevii BY15 Yarrowia lipolytica HY4

The protein composition of 24 individual Maiwa yak milk samples that were collected in the Sichuan province of China was determined by reversed-phase high-performance liquid chromatography. Yak milk differed from cow milk by its high concentration of total proteins (46.2–58.4 g·L−1), total casein (40.2 g·L−1 on average) and the proportion of individual caseins. The high content of β-casein (more than 45%) and consequently the lower proportion of αs-casein (about 40%) together with a small increase in κ-casein (15%) appear to make this milk more favorable for infant nutrition as used by the Tibetan nomads. Also, the whey proteins, β-lactoglobulin and serum albumin, showed similarities in centesimal composition with the homologous cow whey proteins. However, this initial study on yak milk proteins has highlighted the lack of knowledge in the literature and underlines that much research is required to optimize the utilization of all components of this milk for people living in extreme climatic environments.La composition protéique de 24 échantillons de lait de yak de race Maiwa, collectés dans la province de Sichuan en Chine, a été déterminée par chromatographie liquide haute performance. Par rapport au lait de vache, le lait de yak présentait des teneurs nettement plus élevées en protéines totales (46.20–58.40 g·L−1) et en caséine (40.2 g·L−1 en moyenne). Les différences portaient aussi sur la proportion des caséines individuelles, la caséine β représentant plus de 45 % de la caséine entière, la caséine αs, environ 40 % et la caséine κ, environ 15 %. Ces proportions proches de celles existant dans la caséine du lait humain sont probablement la raison de la consommation usuelle de ce lait par les nourrissons des nomades tibétains. Les déterminations des protéines solubles également réalisées dans le cadre de cette étude montraient une forte similarité de composition en β-lactoglobuline et sérum albumine par rapport aux protéines homologues du lait de vache. Ces premiers résultats sur les protéines du lait de yak mettent en évidence la faiblesse des connaissances disponibles sur ce sujet et a contrario l’effort de recherches qui se doit d’être réalisé pour une utilisation la mieux adaptée possible des composants de ce lait aux besoins des populations vivant dans un environnement climatique extrême.RP-HPLC 24 (46.2–58.4 g·L−1) (40.2 g·L−1) β- 45%) α- 40% κ-15 % β-

Four isoforms of polyphenol oxidases (PPOs) were characterised in purified extracts of coats (PPOIa and PPOIb) and pods (PPOIIa and PPOIIb) of green bean (Phaseolus vulgaris L.). The molecular weights of four isoforms have been estimated to be from 57.5 to 39.0 kDa by SDS–PAGE. The PPOII (mixture of PPOIIa and PPOIIb) was used to characterise the PPO of green bean pods. All isoforms activities were stable between pH 6.8 and pH 7.2. PPOIa and PPOII have similar thermal inactivation profiles, and PPOIb has higher thermal stability than that of PPOIa and PPOII. PPOs showed the highest affinity to pyrogallol in all selected substrates. Although activities of PPOs were markedly inhibited by l-ascorbic acid, the activity of PPOI (mixture of PPOIa and PPOIb) was significantly activated by MnSO4 and CaCl2.

To study the chemical properties, the initial recovery of milk components, oiling off, and the textural properties of the cheese during a 60-day refrigerated storage period, skim milk was microfiltered through a 1.4-μm ceramic membrane to remove bacteria, and then low-moisture Mozzarella cheese was manufactured from medium-concentration factor (CF) microfiltration (MF) (0.1 μm of pore size, CF = 2.3) retentate with added cream. The changes in expressible serum (ES) were also studied. Three cheese-making trials were conducted on Mozzarella cheese milk using two different methods: MF and control. Changes in the levels of proteolysis patterns were monitored using pH 4.6-soluble nitrogen (SN), initially higher for microfiltration Mozzarella cheese (MMC) because of the higher content of caseinomacropeptide, and 12% trichloroacetic acid TCA-SN, and using SDS-PAGE. The levels of the secondary proteolysis (12% TCA-SN) were significantly higher in control Mozzarella cheese (CMC). The CMC showed a greater release of free oil at the beginning of aging time but this release was always lower than that observed for MMC. The textural characteristics (hardness, springiness, and cohesiveness) of both cheeses have significant differences, highly correlated to proteolysis indicators, during the ripening time. It is suggested that the differences in composition, proteolysis, oiling off, and textural characteristics in both the cheese and the ES attributes arise mainly as a result of the double content of calcium salts in 0.1-μm MF cheese issued from milk enriched with 2.3 times casein content. Indeed, the high content in calcium salts is known to inhibit autolysis of mesophilic lactic starter by increasing the buffering capacity of cheese aqueous phase, and then causing a slowdown of proteolysis. It likely leads to a different structuration of fat in Mozzarella cheese causing higher oiling off. The results obtained in this study show the possibility of making Mozzarella cheese from milk that has 2.3 times more micellar casein (50 g·kg−1), and to obtain products similar to those obtained from usual milk, adjustment of calcium salt mineralization is required.1.4 μm 0.1 μm 2.3 Mozzarella 60 d pH 4.6-SN 12% TCA-SN SDS-PAGE Mozzarella (pH 4.6-SN) Mozzarella Mozzarella Mozzarella Mozzarella 0.1 μm 2.3 2.3 Mozzarella MozzarellaAprès élimination des bactéries contaminantes par microfiltration à l’aide d’une membrane céramique 1,4 μm, le fromage Mozzarella à extrait sec élevé était fabriqué à partir de lait concentré 2,3 fois par microfiltration sur membrane 0,1 μm, standardisé en matière grasse par addition de crème. Les fromages obtenus (MMC) ont été caractérisés, par rapport à des témoins (CMC) fabriqués à l’aide de lait seulement épuré par MF 1,4 μm, au plan des rendements de transformation, de leurs paramètres physicochimiques, de leur exsudation de matière grasse, de leurs propriétés texturales et des variations de composition de leur phase aqueuse interne pendant 60 jours de conservation au froid. Trois expérimentations ont été réalisées. Les cinétiques de protéolyse étaient appréciées par la mesure de l’azote soluble à pH 4,6, initialement supérieure pour les fromages MMC probablement en raison de leur teneur plus élevée en caséinomacropeptide, de l’azote soluble dans le TCA 12 % et par électrophorèse en gel d’acrylamide. Elles montraient une protéolyse secondaire significativement supérieure dans les fromages CMC. L’exsudation de matière grasse des fromages s’accroissait durant l’affinage, elle était hautement corrélée avec les indicateurs de protéolyse mais restait toujours supérieure pour les fromages MMC. Les caractéristiques de texture des deux types de fromage étaient significativement différentes : fermeté et cohésion constamment plus élevées pour les fromages MMC, élasticité plus élevée en début d’affinage pour les fromages CMC mais quasiment identique au 30ème jour d’affinage. Les différences observées entre les deux types de fromage, tant au plan de leurs caractéristiques initiales qu’au cours de l’évolution de celles-ci lors de l’affinage, découlent très certainement de la minéralisation calcique deux fois plus élevée des fromages MMC, minéralisation calcique inhibant les mécanismes d’autolyse des bactéries mésophiles du levain et donc retardant la protéolyse, structurant différemment la matière grasse du caillé et conduisant à une exsudation plus élevée de la matière grasse. Il en résulte que si les résultats obtenus au cours de cette étude démontrent la possibilité de transformer en fromage Mozzarella du lait à teneur en caséine supérieure à 50 g·kg−1 (enrichissement par un facteur de 2,3), l’obtention de produits similaires aux produits obtenus à partir de lait non enrichi en caséine requiert un ajustement de leur minéralisation calcique.

The effect of ball-milling on physicochemical properties of maize starch was evaluated. Results found that the cold water solubility (CWS) of maize starch was positively correlated with the time of milling up to 3 h. There was no significant influence of using a ceramic pot versus a stainless steel pot on CWS. However, following 5 h of ball-milling CWS increased quite dramatically in the ceramic pot (72.6%) and in the stainless steel pot (70.7%), as compared to the untreated maize starches (2.9%). In addition, as CWS increased, the regions of amorphism enlarged at the expense of the crystalline regions, resulting in a change from the native starch state (oval with a smooth surface) to having more of a rough, abrasive surface. Finally, the transparency of the starch increased as CWS increased and that the syneresis of freeze–thawed ball-milled maize starch also increased with an increase in the number of freeze–thaw cycles.

Milled rice from 11 varieties, with amylose levels from 1.2 to 35.6% dry base, were collected to study the impacts of amylose content on starch retrogradation and textural properties of cooked rice during storage. The relationship between amylose content and different properties was determined using Pearson correlation. Starch retrogradation enthalpy (ΔHr) of cooked rice was determined by differential scanning calorimetry. ΔHr values were found to be positively correlated with amylose content (0.603 ≤ r ≤ 0.822, P < 0.01) during storage. Textural properties were determined by a Texture Analyser. The hardness of cooked rice showed a positive correlation with amylose content (0.706 ≤ r ≤ 0.866, P < 0.01) and a positive correlation with ΔHr of cooked rice (r = 0.650, P < 0.01) during storage. The adhesiveness showed a negative correlation with amylose content (−0.929 ≤ r ≤ −0.678, P < 0.01) and a negative correlation with ΔHr of cooked rice (r = −0.833, P < 0.01) during storage. Hardness showed a negative correlation with adhesiveness (r = −0.820, P < 0.01). These results indicated that amylose content has significant effects on starch retrogradation and textural properties of cooked rice. The cooked rice with high amylose content is easy to retrograde, the cooked rice with low amylose content retrograded slowly. Sarch retrogradation contributes to the changes of textural properties of cooked rice during storage.

The effects of divalent metal ions (Ca2+, Mg2+, Fe2+, and Cu2+) on the growth, β-oxidation system, and thioesterase activity of Lactococcus lactis were investigated. Different metal ions significantly influenced the growth of L. lactis: Ca2+ and Fe2+ accelerated growth, whereas Cu2+ inhibited growth. Furthermore, Mg2+ inhibited growth of L. lactis at a low concentration but stimulated growth of L. lactis at a high concentration. The divalent metal ions had significant effects on activity of the 4 key enzymes of the β-oxidation system (acyl-CoA dehydrogenase, enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and thiolase) and thioesterase of L. lactis. The activity of acyl-CoA dehydrogenases increased markedly in the presence of Ca2+ and Mg2+, whereas it decreased with 1 mmol/L Fe2+ or 12 mmol/L Mg2+. All the metal ions could induce activity of enoyl-CoA hydratase. In addition, 12 mmol/L Mg2+ significantly stimulated activity of L-3-hydroxyacyl-CoA dehydrogenase, and all metal ions could induce activity of thiolase, although thiolase activity decreased significantly when 0.05 mmol/L Cu2+ was added into M17 broth. Inhibition of thioesterase activity by all 4 metal ions could be reversed by 2 mmol/L Ca2+. These results help us understand the effect of metal ions on the β-oxidation system and thioesterase activity of Lactococcus lactis.

Heat stability of yak milk protein reached a maximum at approximately pH 6.8 and was low at pH < 6.4 and pH > 7.0. At pH 6.4, the particle size of yak milk increased by approximately 20 and 25 nm when heated at 140 °C for 2 min and 120 °C for 10 min, respectively. The particle size of heated yak milk decreased markedly with increasing pH. The content of κ-casein dissociated from the casein micelles increased from 5.7% to 9.5% at pH 6.4–76.3% and 81.5% at pH 7.2 when yak milk was heated at 140 °C for 2 min and 120 °C for 10 min, respectively. The proteins αS1-casein and β-casein showed a much lesser extent of dissociation from the micelles than did κ-casein. The levels of α-lactalbumin and β-lactoglobulin in ultracentrifugal supernatants increased from pH 6.4 to pH 7.2 and decreased above pH 7.2.

•The starch-palmitic acid complex was prepared through a combination of high pressure homogenization and heating.•Increasing homogenization pressure will increase the complex index.•X-ray diffraction patterns indicated the formation of V-helical complexes between starch and palmitic acid.•Thermal properties, viscosity and particle size of starch-palmitic acid complexes were study.Aqueous mixtures of defatted corn starch and palmitic acid were heated and high pressure homogenized in order to form amylose inclusion complexes. The effects of homogenization pressure (0–120 MPa) and palmitic acid concentration (0.5–8% based on starch content) on starch-palmitic acid complex formation as well as on complex index, X-ray diffraction, thermal properties, viscosity and particle size were investigated. Complex index increased with an increase in the amount of palmitic acid and homogenization pressure, and reached a maximum value (about 60%) when the fatty acid content was 4% and the homogenization pressure was 100 MPa. X-ray diffraction patterns indicated the formation of V-helical complexes between starch and palmitic acid. This technology could prospectively be used in prepared starch-lipid complexes.

•Thermal stability of the purified lectin from black turtle bean was studied.•Bean processing conditions at neutral pH were evaluated by HA.•Two-way ANOVA was used to verify the effects of temperature and time.•Conformational changes of the lectin were confirmed by intrinsic fluorescence.•First-order reaction kinetic model was developed to analyze thermal inactivation.The thermal stability of purified lectin from the black turtle bean was studied at temperatures between 70 °C and 90 °C over treatment times from 0 to 30 min. The results of the hemagglutinating activity and the intrinsic fluorescence assays indicated that the thermal inactivation is associated with the unfolding of the protein. Based on the two-way analysis of variance, the heating temperature and treatment time significantly affected the stability of the lectin during thermal treatments. Analysis of kinetic data suggested that the thermal stability of the lectin followed first-order reaction kinetics. The activation energy for the lectin was 78.80 kJ/mol. This higher activation energy suggested hydrophobic stability and thermal sensitivity of the lectin during thermal processing. Additionally, a high temperature and short treatment time might eliminate the anti-nutritional functions of the lectin. The linear relationship observed could be used as a quality indicator for the thermal processing of the black turtle bean.

The influence of fatty acids on the β-oxidation system and thioesterase of Lactococcus lactis was investigated in this study. The results showed that fatty acids (C8:0–C16:0) significantly inhibited the growth of Lactococcus lactis, and laurate (C12:0) had the highest bactericidal effects. We detected the maximum activity of β-oxidation at different incubation times (8, 12, and 18 h) to be 6.460, 7.751, and 8.203, respectively, and the maximum activity of thioesterase at different incubation times (8, 12, and 18 h) to be 19.498, 27.180, and 12.800, respectively. Fatty acids were seen to induce the β-oxidation system and activity of thioesterase; decanoic acid (C10:0) and palmitic acid (C16:0) were also seen to induce the β-oxidation system of Lactococcus lactis, but the induced ability was significantly different. Octanoic acid (C8:0) and palmitic acid (C16:0) were seen to induce thioesterase activity in Lactococcus lactis. When 1 mM palmitic acid (C16:0) was added to M17 broth, the activity of thioesterase increased 5-fold after 2 min; however, adding octanoic acid (C8:0) changed the activity little. Evidence showed that the ability to induce the β-oxidation system and thioesterase activity was related to the fatty acids’ chain lengths.