调配型酸性豆乳饮料工艺及稳定性影响因素的研究

系统地研究了调配型酸性豆乳饮料的生产工艺及影响其稳定性的各种因素 ,得出结论 :豆乳浓度越高饮料越不稳定 ;在饮料 p H远离蛋白质等电点情况下 ,p H越低越不稳定 ;搅拌速度在不产生气泡条件下越快越好 ;均质最佳条件为 1 8～ 2 5MPa,50～ 70℃ ,加酸前后各均质一次 ;调配温度选择低于 70℃的较低温度 ;30 min,60～ 70℃杀菌 ;最佳调配顺序为先将糖、水、稳定剂充分混合 ,再加入混有络合剂的豆浆 ,最后调酸 ;络合剂以加入 0 .1 7%多聚磷酸钠稳定性较好 ;以大众口味确定蔗糖添加量。     

响应面法优化葛根酸豆奶配方

本文以大豆、葛根、白砂糖为主要原料,通过单因素实验方法,明确白砂糖、葛根汁、菌种量和发酵时间对葛根酸豆奶的感官评分和乳酸含量的影响。按照Box-Behnken设计实验方案,运用响应面分析法建立二阶多项非线性回归方程和数据模型,以感官评分为指标优化葛根酸豆奶配方,确定白砂糖添加量、葛根汁添加量和菌种的添加量,探索葛根酸豆奶的最佳配方。结果表明:优化后验证实验的感官评分为90.3分（n=3）,与预测值89.62分接近,偏差为0.76%,得到葛根酸豆奶的最佳添加量,白砂糖的添加量为7.86%,葛根汁的添加量为18.0%,菌种添加量0.35%。此研究结果下的葛根酸豆奶的质构、持水性、乳酸菌、蛋白质含量和总黄酮含量,优于市售同类产品,具有商业推广价值。      

生物解离对豆乳体系稳定性的研究

本文研究了碱性蛋白酶生物解离0、10、20和30 min条件下豆乳体系的粒径分布、Zeta电位、流变学特性、乳化活性及乳化稳定性的变化。并通过多重光散射稳定性分析考察豆乳体系的稳定性。研究结果表明,当生物解离20 min时,豆乳体系的平均粒径为456 nm,豆乳的粒径主要分布在100~1000 nm,随着生物解离时间的增加,粒径分布更集中,平均粒径不断降低。当生物解离作用时间为30 min时,电位绝对值最大为30.3 mV。但随着解离时间的增加,乳化活性及乳化稳定性在一定程度上降低。另外,生物解离不会改变豆乳的流体性质。多重光散射分析表明,豆浆体系的粒径更加均匀和稳定。综上,生物解离技术可作为提高豆乳体系稳定性的一种手段。     

Effect of partial substitution of cow's milk with soymilk on yield and quality attributes of West African soft cheese

Warankasi , a soft unripened cheese, was made from milk containing up to 20% soymilk. The best cheeses were obtained from soymilk prepared by grinding in boiling water soybeans that had been preheated by dipping in hot water, 95–100°C, for 15–20 sec. Cheeses containing soymilk were comparable with controls made from whole cow's milk in yield, nitrogen and fat content, and flavour. Cheeses with up to 10% soymilk had a slight brownish colour, but overall acceptability was not impaired, relative to controls. Cheeses with 20% soymilk were acceptable although inferior to controls.     

Improved Acid, Flavor and Volatile Compound Production in a High Protein and Fiber Soymilk Yogurt-like Product

The effects of added caseinate (CAS), casein hydrolyzate (CASHY) and whey protein hydrolyzate (WPHY) on acid, flavor and volatile compound production in a high protein and fiber soymilk yogurt-like product were studied. High protein and fiber soymilk, produced by blending soaked, boiled and dehulled soybeans with Swiss cheese whey ultrafiltration permeate, was fermented with a mixed S. thermophilus and L. bulgaricus yogurt culture. The concentrations of lactic acid, key volatile compounds, i.e., acetaldehyde, acetone, and diacetyl, and the flavor and texture of the resulting soymilk based yogurt formulated with added CAS or CASHY were comparable to those in a milk yogurt control.     

Effect of feed concentration and inlet air temperature on the properties of soymilk powder obtained by spray drying

In this study, soymilk powder was produced by spray drying. The inlet air temperature of spray dryer was varied from 200 to 280°C and the feed concentration was varied from 15 to 25% (w/v). Response surface methodology was used to examine the effects of these independent variables on the detailed characteristics in terms of physical, structural, functional properties of powder. Overall, results show that rising the inlet air temperature caused a decrease in tapped and loose bulk density, true density, filling rate, water holding capacity, and water content of powder; and an increase in compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index. An increase in feed concentration led to an increase in true density, compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index; and a decrease in tapped and loose bulk density, filling rate, water holding capacity, and water content; whereas oil holding capacity might be increased or decreased and it depended almost solely on the feed concentration.     

干法制浆工艺对豆浆品质的影响

采用高速粉碎机对大豆进行干法粉碎制取豆粉,以豆粉为原料分别制作熟浆豆浆和全豆豆浆,省去传统豆浆制作过程中的大豆浸泡工序。以豆浆平均粒径和稳定性为质量指标,通过单因素试验和正交试验,优化了豆浆制作工艺参数。结果表明:熟浆豆浆的最佳工艺参数为大豆粉碎时间120s、料水比1:11(g/mL)、保温时间30min;全豆豆浆的最佳工艺参数为大豆粉碎时间120 s、料水比1:12(g/mL)、保温时间15min。与传统全豆豆浆相比,干法全豆豆浆的平均粒径降低了66.43%,可溶性固形物以及可溶性蛋白质含量分别提高14.41%和16.57%;与传统熟浆豆浆相比,干法熟浆豆浆的平均粒径提高78.03%,可溶性固形物含量以及可溶性蛋白质含量分别提高42.36%和42.76%。干法工艺所制得的豆浆与传统豆浆相比在感官评价上无显著差异(P0.05)。     

Textural properties of mango soy fortified probiotic yoghurt: optimisation of inoculum level of yoghurt and probiotic culture

The effect of yoghurt bacteria and probiotic culture on the textural characteristics of mango soy fortified probiotic yoghurt (MSFPY) is studied. The TA-XT2 Texture Analyser was used to measure the textural characteristics of MSFPY prepared from blends containing varying proportions of yoghurt bacteria [ Streptococcus thermophilus (ST), Lactobacillus bulgaricus (LB)] and probiotic culture [ Bifidobacterium bifidus (BB), Lactobacillus acidophilus (LA)]. MSFPY samples were prepared by using blends of 78.3% toned milk, 14.5% soy milk and 7.2% mango pulp. Texture profile data were used to develop regression models for dependent variables – hardness, cohesiveness, adhesiveness, springiness and gumminess. The optimisation of culture addition was done by comparing the yoghurt with the MSFY as control sample (ST and LB at 2%, 1:1) The mean optimum culture addition rate of –1.43 (0.79%) ST, –1.51 (0.75%) LB, –1.43 (0.79%) BB and –1.10 (0.95%) LA is recommended for yielding an acceptable and good quality of MSFPY.     

Soymilk concentration by ultrafiltration: effects of pore size and transmembrane pressure on filtration performance

The effects of membrane pore size and operating pressure on filtration flux, membrane fouling and solute rejections of soymilk during ultrafiltration were studied. Soymilk was concentrated from an initial level of 6.5% solid content to 20% solid content using ultrafiltration membranes. Hollow fibre cross‐flow type cartridges having molecular weight cut‐off (MWCO) as 1, 10 and 30 kDa were used in the experiments. Filtration data were satisfactorily fitted to De La Garza and Boulton's exponential model to find the exponential fouling coefficient (k) and the membrane resistance (R_m). The permeate fluxes obtained in 10 and 30‐kDa MWCO membranes were found to be approximately four times higher than that of 1‐kDa MWCO membrane, at transmembrane pressure between 100 and 240 kPa. The average flux obtained was 0.7, 3.15 and 2.7 L m^?2‐h for 1, 10 and 30‐kDa MWCO membranes, respectively. The R_m value of membranes was found to decrease as the MWCO of membranes increased and transmembrane pressure decreased. The total solid content of permeates obtained by these membranes was between 0.45% and 1.4%. Membrane‐concentrated soymilk was found to have lighter colour and almost half the value of viscosity compared with evaporated milk.     

Detection by coupled LC-photodiode array detection and high-resolution Orbitrap MS of dimethyl and diethyl yellow dyes used illegally in processed soymilk curd

An efficient non-target dye-screening system consisting of a liquid chromatography photodiode array coupled with a high-resolution mass spectrometer (HRMS) is described. Visible absorption spectroscopy assisted in locating the peak of an unknown dye in HRMS chromatograms which allowed the accurate molecular weight of the unknown to be obtained. In a study of the adulteration of processed soymilk curd (tofu) with dimethyl yellow, an unexpected unknown dye was discovered. The compound was further purified by gel permeation chromatography and identified by HRMS and proton nuclear magnetic resonance (NMR) as diethyl yellow (solvent yellow 56). This is the first time that diethyl yellow has been reported in foods. The authentic diethyl yellow was then purchased and used as a quantitative standard. Tofu products and their ingredients associated with tofu processing were surveyed. Analysis showed the source of diethyl yellow could be traced to emulsifiers used as ingredient in tofu products. Surveillance work found the concentrations of diethyl yellow ranged from several μg kg^?1 (ppb) in the tofu products to up to hundreds of mg kg^?1 (ppm) in the emulsifiers.