Aqueous enzymatic process assisted by microwave extraction of oil from yellow horn (Xanthoceras sorbifolia Bunge.) seed kernels and its quality evaluation

In this study, aqueous enzymatic process (AEP) assisted by microwave extraction (ME) of oil from yellow horn (Xanthoceras sorbifolia Bunge.) seed kernel was investigated. Central composite design (CCD) and response surface methodology (RSM) were used to optimise an enzyme cocktail (cellulase, hemicellulase, pectinase) for AEP. The main factors of ME were also studied. A maximal oil extraction yield of 55.8% was achieved under optimal conditions. Moreover, scanning electron microscope (SEM) was applied to characterise the extraction process. Analysing chemical composition of the extracted oil by GC–MS showed that the content of unsaturated fatty acids by this emerging method (91.18%) was similar to that by conventional organic solvent extraction (88.76%). In addition, the main physicochemical properties and antioxidant activities of yellow horn oil were measured to evaluate its quality. The present research supported necessary data for the green extraction method of edible oil in food industry.     

Resistant starch and thermal,morphological and textural properties of heat‐moisture treated rice starches with high‐, medium‐ and low‐amylose content

This study investigated the effects of heat‐moisture treatment (HMT) on the resistant starch content and thermal, morphological, and textural properties of rice starches with high‐, medium‐ and low‐amylose content. The starches were adjusted to 15, 20 and 25% moisture levels and heated at 110°C for 1 h. The HMT increased the resistant starch content in all of the rice starches. HMT increased the onset temperature and the gelatinisation temperature range (T_finish–T_onset) and decreased the enthalpy of gelatinisation of rice starches with different amylose contents. This reduction increased with the increase in the moisture content of HMT. The morphology of rice starch granules was altered with the HMT; the granules presented more agglomerated surface. The HMT affected the textural parameters of rice starches; the high‐ and low‐amylose rice starches subjected to 15 and 20% HMT possessed higher gel hardness.     

Improved aqueous solubility,bioaccessibility and cellular uptake of quercetin following pH-driven encapsulation in whey protein isolate

The purpose of this study was to increase the water solubility and potential bioavailability of quercetin by encapsulation in whey protein isolate (WPI) based on a green, efficient pH-driven method. According to the results, the water solubility of quercetin increased by 346.9: times after loading into WPI nanoparticles. When the initial quercetin concentration was 0.25 mg mL⁻¹ and WPI was 2% w/v, the encapsulation efficiency reached 94.1%, the Z-average diameter was 36.63 nm, and the zeta potential was −36.4 mV at pH 7.0. The fluorescence spectroscopy assay suggested the molecular complexation of quercetin and WPI at pH 12.0. X-ray diffraction assay indicated the enclosure of amorphous quercetin in WPI. Correspondingly, the bioaccessibility increased from 2.76% to 31.23% and the Caco-2 cell monolayer uptake increased from 0% to 2.12% after nanoencapsulation. This work confirmed that the pH-driven method is an effective approach to prepare WPI–quercetin nanocapsules to improve physical and potentially biological properties of quercetin.     

Effect of microwave heating time on the gel properties of chicken myofibrillar proteins and their formation mechanism

The present work was conducted to illustrate the mechanism of gel formation of myofibrillar proteins (MPs) under different microwave heating times. The results showed that the denaturation enthalpy (ΔH) of the MPs significantly decreased when the heating time increased from 3 to 9 s and then completely disappeared as the heating time progressed, indicating that the MPs gradually denatured and subsequently aggregated with increasing heating time, which was further verified by the changes in the secondary structure, electrophoretic bands, and gel properties (e.g., water holding capacity and textural profiles) of the MPs. Microstructural images indicated that the MP gel formed under 12 s had the most compact network, indicating that extended microwave heating time could induce quality deterioration of MP gels. Moreover, the hydrophobic forces, electrostatic forces, and disulphide bonds of the MPs gradually intensified with increasing microwave heating time, suggesting that both non-covalent and covalent bonds could promote molecular denaturation and subsequent aggregation of MPs. In addition, correlation analysis revealed that the changes in the molecular conformation of MPs induced by different microwave heating times could effectively regulate the formation of MP gels and their related properties.     

食品乳化剂的介晶理论及实际应用

乳化剂是食品工业中使用最广泛、最重要的一类食品添加剂 ,除具有典型的表面活性作用外 ,还能与食品中碳水化合物、蛋白质、脂类发生特殊的相互作用 ,而起到多种功效。它具有安全可靠 ,使用方便的特点 ,能起到乳化、保鲜、品质改良、起泡等多种功能。根据乳化剂的介晶理论 ,乳化剂具有多晶性 ,即α 晶型、β 初级晶型和 β 三种晶型。乳化剂在使用前只有处于α 晶型结构 ,应用到面包、蛋糕等食品中才能充分发挥作用效果     

Comparative study of the colorants monascus and cochineal used in the preparation of gels made with various gelling agents

The possibilities of using monascus to colour gels were studied by comparing it with cochineal. Gels were prepared with four gelling agents—carrageenan, gellan, gelatine and xanthan—and their colour was measured with a Hunter Lab colorimeter. The equations relating L^* and h with the concentrations of sugar [SU] and colorant [COL] were deduced, and it was found that [COL] had more influence on colour than [SU]. In general, for these four gelling agents the colour of monascus gels is orange-red and the colour of cochineal gels is purplish red. The gels made with xanthan were always the lightest, whether they were made with cochineal or with monascus.     

血清蛋白质加热凝胶的形成

家畜血液中含有丰富的蛋白质。血液的主要成分——血清或血浆与卵白都有经加热可以形成凝胶的相同性质。食品中蛋白质凝胶的形成能力直接影响着食品的品质。通过对一定浓度的牛和猪的血清蛋白质加热形成凝胶强度的评价,分析了血清中主要蛋白质成分在凝胶形成过程中的作用及其机理。结果表明:牛血清的凝胶强度高于猪血清;牛血清中的白蛋白在血清加热凝胶形成过程中起着重要作用;通过加热血清蛋白,蛋白质分子间的二硫键交联形成凝胶;利用血清蛋白质经加热可以形成凝胶的性质将血清添加到食品中,不仅可以改善食品的品质,而且还可以提高食品中蛋白质的含量。     

烟用二醋酸纤维生产过程中飞花的定性表征

为研究烟用二醋酸纤维生产过程中的飞花及其产生机理,采用多角激光散射检测器与凝胶渗透色谱联用、差示扫描量热和电子扫描电镜等方法对飞花进行了表征。结果表明,分子量及其分布、醋酸纤维素的合成过程、纺丝浆液中的凝胶组分和二氧化钛颗粒以及纺丝工艺条件的波动等是造成飞花的主要因素。     

凝胶渗透色谱/气相色谱法测定食用油脂中抗氧化剂特丁基对苯二酚

应用凝胶渗透色谱(GPC)和气相色谱(GC)技术,建立了食用油脂中抗氧化剂叔丁基对苯二酚(TB-HQ)的分析方法。TBHQ在检测范围内具有良好的线性,线性范围在1～1000mg/L之间,相关系数为1。其检出限为0.002mg/mL。加标油样的回收率在87.2%～95.1%之间,相对标准偏差(RSD)小于6.95%。     

响应面优化超声波辅助水酶法提取蜡梅籽蛋白

采用超声波辅助水酶法提取蜡梅籽蛋白,探讨超声波处理时间与温度、酶用量、碱浸提液pH、酶解温度、酶解时间及料液比对蜡梅籽蛋白提取效果的影响。应用Box-Behnken设计4因素3水平的试验,依据响应面分析确定最优的提取工艺条件。结果表明,最佳提取工艺参数为:超声波处理时间15min,超声波处理温度50℃,料液比1:8,酶用量3.64%,碱浸提pH9.72,酶解温度45℃,酶解时间163min。在此条件下,蜡梅籽蛋白的得率为31.95%。