亲水胶体在牛奶布丁中的应用

以新鲜牛奶和白砂糖为原料,选择高酰基结冷胶、低酰基结冷胶、卡拉胶、刺槐豆胶、黄原胶、魔芋胶、果胶、琼脂、羧甲基纤维素钠和明胶十种亲水性胶体,探讨其种类和添加量对牛奶布丁感官品质的影响。结果表明,能够形成凝胶的亲水胶体为高酰基结冷胶、低酰基结冷胶、卡拉胶、果胶、琼脂和明胶,其对应的最佳添加量分别为0.2%,0.1%,0.2%,0.7%,0.3%和1.1%。以明胶、卡拉胶、高酰基结冷胶复配,正交试验结果表明明胶添加量0.4%,高酰基结冷胶添加量0.1%,卡拉胶添加量0.1%,总添加量为0.6%,此时感官品评分值最高。     

高、低酰基结冷胶的乳化活性及稳定性

以高酰基结冷胶(HA)、低酰基结冷胶(LA)为乳化剂,以中链甘油酸酯(MCT)为油相,通过超声乳化法制备水包油(O/W)乳液。以阿拉伯胶(GA)为对照,考察添加不同浓度、类型结冷胶条件下乳液的外观变化、界面张力、Zeta-电位和粒径分布等,比较高、低酰基结冷胶的乳化特性。研究结果表明,以HA为乳化剂制备的O/W乳液平均粒径略大于以GA制备的乳液,而LA乳液粒径最大;HA乳液-电位绝对值整体显著大于GA乳液(P0.05),且在最优浓度条件下HA乳液界面张力小于GA乳液,因此HA乳液乳化稳定性优于GA乳液。而LA乳液ζ-电位绝对值最小,界面张力最大,其乳液稳定性最差。储藏试验表明,HA乳液稳定性高于GA乳液,且在60℃储藏条件下的粒径变化率显著小于GA乳液。LA乳液极不稳定,制备当天即出现分层现象。本文着重研究不同酰基结冷胶在乳化性能方面的应用差异,结果为高酰基结冷胶具有良好的乳化活性和稳定性。此结果对高酰基结冷胶的品质提升和应用推广等方面具有重要的意义。     

高酰基结冷胶的溶胶和凝胶特性研究及结构初步分析

采用黏度计和质构仪对高酰基结冷胶的溶胶和凝胶性质进行研究。结果表明：高酰基结冷胶在质量浓度为 0.05～0.1g/100mL 时,表观黏度随质量浓度增加而增加,并呈现假塑性流体特性;在质量浓度为0.2～0.5g/100mL时形成凝胶,凝胶强度受胶体及 Ca2+ 质量浓度的影响明显,同时高酰基结冷胶比例增加,高低复配胶体的凝胶强度减小。并利用红外光谱扫描和核磁共振技术对高酰基结冷胶结构进行初步分析。     

低酰基和高酰基结冷胶对模型饮料中百香果皮花色苷热稳定性的影响

利用pH示差法和全自动色差仪,结合降解动力学模型,研究低酰基(low acyl,LA)和高酰基(high acyl,HA)结冷胶对抗坏血酸(VC)存在下含百香果皮(passion fruit peel,PFP)花色苷的模型饮料在85℃条件下热处理0、1、2、3、4、5 h后热稳定性的影响,并通过超高效液相色谱-四极杆-飞行时间串联质谱联用仪分析鉴定PFP花色苷组分。结果表明:热处理期间,PFP、PFP+VC、PFP+VC+LA和PFP+VC+HA 4种模型饮料体系中花色苷含量均呈下降趋势,花色苷的降解符合一级动力学模型,其半衰期分别为308.44、155.09、189.69 min和217.92 min;低质量分数(0.2%～0.5%)的结冷胶可以提高花色苷的稳定性,且HA结冷胶与花色苷结合的相互作用强于LA结冷胶;在加热1～5 h范围内,L*值显著增加,a*值显著减小,b*值显著减小(P0.05),即4种模型饮料体系呈色变亮、红色变淡、黄色加深,PFP花色苷出现广泛褪色现象,但较0～1 h褪色反应慢;从PFP中鉴定出4种花色苷,分别为矢车菊素-3-槐糖苷、矢车菊素-3-葡萄糖、矢车菊素-3-芸香糖苷和芍药素-3-葡萄糖苷。     

结冷胶溶液凝胶特性的研究

结冷胶是一种新型食品添加剂。其存在形式为天然式和低酰基式。天然式结冷胶溶液的凝胶特性是粘弹性体,低酰基结冷胶溶液是凝胶体。将两种形式的结冷胶溶液在相同条件下与卡拉胶、琼脂溶液进行了比较,得出两种形式的结冷胶溶液在0.05％时可形成凝胶,大大低于卡拉胶和琼脂的成凝胶浓度。     

钙盐和明胶对高酰基结冷胶的凝胶特性的影响

利用质构仪质构剖面分析法（TPA）研究了不同浓度的氯化钙、乳酸钙、葡萄糖酸钙对高酰基结冷胶凝胶特性的影响；明胶添加量对高酰基结冷胶凝胶特性的影响；以及三种钙盐和明胶对高酰基结冷胶凝胶特性的影响。结果表明，三种钙盐都可以提高高酰基结冷胶的凝胶强度。添加明胶可以提高高酰基结冷胶的凝胶强度、咀嚼性、弹性和内聚性。对比三种钙盐，添加乳酸钙的高酰基结冷胶-明胶复配胶凝胶特性最好。因此，适量的钙盐和明胶可以提高高酰基结冷胶的凝胶特性，为高酰基结冷胶在食品中的应用提供理论参考。     

花生蛋白质凝胶食品的生产工艺研究

研究了以花生仁为原料,用氯化钙作为凝固剂的花生蛋白质凝胶食品的生产工艺,并对影响花生蛋白质胶凝性的各因素进行实验研究,得出它们与成品之间的关系,并通过正交实验确定制作产品的最佳工艺条件。花生浆浓度为1∶6,凝固剂添加量为每200mL花生浆使用5%的氯化钙溶液6mL,点浆温度为85℃,pH为6,制作的花生蛋白食品凝固状态好,有弹性,质地细腻,颜色为乳白色,口感细嫩,有典型的花生香气。     

不同因素对乳清蛋白乳化凝胶特性的影响

探讨了葡萄糖酸-δ-内酯（GDL）、中性盐（NaCl、CaCl_2）以及增稠剂对乳清分离蛋白乳化凝胶强度、弹性以及保水性的影响。结果表明：GDL为0.6%、NaCl为1%、CaCl_2为0.25%、增稠剂卡拉胶为0.2%以及黄原胶为0.1%制备的乳化凝胶强度显著提高。GDL为0.4%、NaCl为0.75%、CaCl_2为0.25%、增稠剂卡拉胶为0.05%以及黄原胶为0.15%制备的乳化凝胶弹性显著提高。增稠剂卡拉胶为0.15%、黄原胶为0.1%所制备的乳化凝胶保水性显著提高。     

花生豆腐加工过程中凝胶质构形成研究进展

花生豆腐是一种新型花生蛋白凝胶制品,其凝胶质构形成与工艺技术、加工条件和原料特性等密切相关。本文重点论述典型加工工艺对豆腐质构的影响,加工过程中花生乳功能特性如热特性、流变特性变化以及豆腐凝胶微结构变化,指出花生豆腐研究中存在的问题,展望未来的发展趋势,旨在为花生豆腐加工提供理论支撑和技术指导。     

肌球蛋白与κ-卡拉胶混合胶凝机理的研究

通过研究pH、离子强度和钾离子对肌球蛋白与卡拉胶混合溶液粘弹性的影响,揭示了肌球蛋白与κ-卡拉胶混合胶凝的机理。肌球蛋白与卡拉胶混合胶凝的过程是肌球蛋白在加热过程中首先胶凝,然后卡拉胶在降温过程中胶凝并使体系胶凝能力增强,卡拉胶的作用一般处于次要地位。较高pH可导致肌球蛋白与卡拉胶混合凝胶能力下降;低离子强度使肌球蛋白与卡拉胶混合胶凝能力明显增强;钾离子促进了卡拉胶的凝胶作用,在肌球蛋白与卡拉胶混合胶凝过程中占主要地位。     

Effects of dietary supplements of algae,containing polyunsaturated fatty acids,on milk yield and the composition of milk products in dairy ewes

Thirty-two lactating Karagouniko ewes were allocated at random to four groups for 6 weeks, to examine the effect of four diets: C (control treatment, ration without algae); LA (ration with low level of algae); MA (ration with medium level of algae) and HA (ration with high level of algae); containing 0, 23.5, 47 and 94 g algae, respectively, on the enrichment of milk and dairy products. Addition of algae reduced (P < 0.001) DM intake for treatments MA and HA. Milk yield did not differ between treatments but milk composition was significantly affected by dietary inclusion of algae. Milk fat content was significantly increased (P < 0.001) for treatment HA whereas milk protein content was significantly increased (P < 0.001) for all treatments containing algae. Milk from treatments LA, MA and HA was significantly enriched in the following PUFA: C20:5 (n-3) (0.4-2.1%), C22:5 (n-6) (0.8-4.1%), C22:6 (n-3) (4.3-12.4%) (P < 0.001) and C22:5 (n-3) (2.1-3.1%) (P < 0.05), which were not detected in control milk. Feta cheese and yogurts produced from the enriched milk had identical composition with the milk, and would be characterized as healthy foods. The ratio of n-6 to n-3 fatty acids was 2.5-4.5.     

The effect of alfalfa (Medicago sativa) silage chop length and inclusion rate within a total mixed ration on the ability of lactating dairy cows to cope with a short-term feed withholding and refeeding challenge

The objectives of the study were (1) to test whether 6 h of feed deprivation followed by refeeding induces an acidosis challenge in dairy cattle and (2) to quantify the acidosis challenge mitigation potential of increased alfalfa silage concentration in the diet. Alfalfa silage constituted either 25 or 75% of forage dry matter (DM) replacing corn silage [low (LA) or high alfalfa (HA)] and was chopped to either 14 or 19 mm theoretical length [short (S) or long (L)]. Dietary treatments LAS, LAL, HAS, or HAL were offered to 4 rumen-cannulated Holstein dairy cattle (161 d in milk; 5th or 6th parity) in a 4 × 4 Latin square design study with 21-d periods. Starch concentration was 69 g/kg of DM higher for LA diets than HA diets. Feed was withheld for 6 h followed by ad libitum refeeding on d 18 of each period. Measurements of DM intake, milk yield and composition, rumen pH, and eating and rumination behavior were taken on 1 baseline day, the challenge day, and 2 further recovery days. After refeeding, rumen pH was reduced in cows fed LA diets but not HA diets. Feeding LAL resulted in the greatest subclinical acidosis risk (pH <5.8 for 355 min on the first recovery day). Animals fed LA produced 4.4 L less milk on the challenge day in comparison to baseline. It was concluded that short-term feed deprivation detrimentally affected rumen health and milk yield in dairy cattle normally fed ad libitum, but had no effect on DM intake or milk composition. Feeding alfalfa silage in place of corn silage mitigated acidosis risk due to interrupted feed supply, likely due to a combination of lower starch concentration in HA diets, greater effective fiber concentration, and higher buffering capacity of alfalfa relative to corn silage.     

Influence of rate of inclusion of microalgae on the sensory characteristics and fatty acid composition of cheese and performance of dairy cows

Modification of milk and cheese fat to contain long-chain n-3 fatty acids (FA) by feeding microalgae (ALG) to dairy cows has the potential to improve human health, but the subsequent effect on the sensory attributes of dairy products is unclear. The objective was to determine the effect of feeding dairy cows different amounts of ALG that was rich in docosahexaenoic acid (DHA) on milk and cheese FA profile, cheese sensory attributes, and cow performance. Twenty Holstein dairy cows were randomly allocated to 1 of 4 dietary treatments in a 4 × 4 row and column design, with 4 periods of 28 d, with cheddar cheese production and animal performance measurements undertaken during the final 7 d of each period. Cows were fed a basal diet that was supplemented with ALG (Schizochytrium limancinum) at 4 rates: 0 (control, C), 50 (LA), 100 (MA), or 150 g (HA) of ALG per cow per day. We found that both milk and cheese fat content of DHA increased linearly with ALG feed rate and was 0.29 g/100 g FA higher in milk and cheese from cows fed HA compared with C. Supplementation with ALG linearly reduced the content of saturated FA and the ratio of n-6:n-3 FA in milk and cheese. Supplementation with ALG altered 20 out of the 32 sensory attributes, with a linear increase in cheese air holes, nutty flavor, and dry mouth aftertaste with ALG inclusion. Creaminess of cheese decreased with ALG inclusion rate and was positively correlated with saturated FA content. We also observed a quadratic effect on fruity odor, which was highest in cheese from cows fed HA and lowest in LA, and firmness and crumbliness texture, being highest in MA and lowest in HA. Supplementation with ALG had no effect on the dry matter intake, milk yield, or live weight change of the cows, with mean values of 23.1, 38.5, and 0.34 kg/d respectively, but milk fat content decreased linearly, and energy-corrected milk yield tended to decrease linearly with rate of ALG inclusion (mean values of 39.6, 38.4, 37.1, and 35.9 g/kg, and 41.3, 41.3, 40.5, and 39.4 kg/d for C, LA, MA, and HA, respectively). We conclude that feeding ALG to high-yielding dairy cows improved milk and cheese content of DHA and altered cheese taste but not cow performance, although milk fat content reduced as inclusion rate increased.     

基于反射物理模型的稳定分析仪(Turbiscan)技术研究胶体对花生牛乳稳定性影响

以未经胶体悬浮的花生牛乳为对照,利用Malvern 粒度仪测定灭菌纯牛乳和花生牛乳粒径分布,并基于反射物理模型的背散射光检测技术研究结冷胶和微晶纤维素分别对花生牛乳的稳定效果。结果表明：花生牛乳较纯牛乳的粒径分布中明显地增加了花生微粒所形成的峰,其中,花生微粒的粒径主要分布于20～500μm;空白对照组、微晶纤维素(MCC)组和HM-B 结冷胶组的花生牛乳体系的稳定动力学参数(SI)分别为0.88、0.45 和0.17,3 个体系的浮油速率没有显著变化,而MCC 和HM-B 结冷胶对沉淀现象具有显著改善,其中,HM-B 结冷胶悬浮颗粒的能力较MCC 更强,更适合于花生牛乳体系的悬浮。     

Effects of lauric and myristic acids on ruminal fermentation, production, and milk fatty acid composition in lactating dairy cows

The objectives of this experiment were to investigate the effects of lauric (LA) and myristic (MA) acids on ruminal fermentation, production, and milk fatty acid (FA) profile in lactating dairy cows and to identify the FA responsible for the methanogen-suppressing effect of coconut oil. The experiment was conducted as a replicated 3 × 3 Latin square. Six ruminally cannulated cows (95 ± 26.4 DIM) were subjected to the following treatments: 240 g/cow per day each of stearic acid (SA, control), LA, or MA. Experimental periods were 28 d and cows were refaunated between periods. Lauric acid reduced protozoal counts in the rumen by 96%, as well as acetate, total VFA, and microbial N outflow from the rumen, compared with SA and MA. Ruminal methane production was not affected by treatment. Dry matter intake was reduced 35% by LA compared with SA and MA, which resulted in decreased milk yield. Milk fat content also was depressed by LA compared with SA and MA. Treatment had no effect on milk protein content. All treatments increased milk concentration of the respective treatment FA. Concentration of C12:0 was more than doubled by LA, and C14:0 was increased (45%) by MA compared with SA. Concentration of milk FA < C16 was 20% lower for LA than MA. Concentrations of trans 18:1 FA (except trans 12) and CLA isomers were increased by LA compared with SA and MA. Overall, the concentrations of saturated FA in milk fat were reduced, and that of > C16 FA and MUFA were increased, by LA compared with the other treatments. In this study, LA had profound effects on ruminal fermentation, mediated through inhibited microbial populations, and decreased DMI, milk yield, and milk fat content. Despite the significant decrease in protozoal counts, however, LA had no effect on ruminal methane production. Thus, the antimethanogenic effect of coconut oil, observed in related studies, is likely due to total FA application level, the additive effect of LA and MA, or a combination of both. Both LA and MA modified milk FA profile significantly.     

Rheological characterization and activation energy values of binary mixtures of gellan

The present study determined the flow behavior and activation energy of high (HA) and low (LA) acyl gellan dispersions (0.2%) and their mixtures as a function of preparation temperature (25 and 90 °C) and of the presence or absence of Ca²⁺ (30 mM). Heated gellan mixtures containing calcium were acidified with δ-gluconolactone to obtain gels and determine linear viscoelasticity using the Kelvin–Voigt model. The studied dispersions showed non-Newtonian shear-thinning behavior. HA dispersions (with and without Ca²⁺) showed the highest activation energy values, 88.60 and 51.18 kJ/mol. Whereas, LA dispersions showed the lowest activation energy values, 3.73 and 9.19 kJ/mol. With respect to the rheological studies, it was observed that the relationships between HA and LA gellan did not affect the recovery percentages because similar values were obtained (86.90–90.00%), and this behavior along with the mean viscosity values obtained in the gel mixtures could indicate that the hydrogen bond formation between both gellan helix (HA, LA) is possible. These results can contribute to possible industrial applications of gellans in the development of new alimentary products.     

Sensory,physicochemical and rheological properties of plant-based milk alternatives made from soybean,peanut, adlay,adzuki bean,oat and buckwheat

This study investigated the physicochemical and sensory properties of six types of plant-based milk alternatives prepared from soybean, peanut, adlay, adzuki bean, oat and buckwheat at a 1:9 grain-to-water ratio. The results revealed that all plant-based milk types had stable hydrocolloid systems, except for the buckwheat milk alternative that had undergone a gelatinisation process that affected its rheological and sensory properties. The pH values and total solid content of the prepared plant-based milk samples ranged between 6.60 to 6.83 and 2.13 to 8.17 g/100 mL, respectively. The sensory results showed that the overall liking score of adlay, adzuki bean and peanut milk alternative was 5.32, 5.30 and 6.10, respectively, suggesting a potential for commercial production. In conclusion, this investigation provides new insights on several new plant sources for plant-based milk alternatives. Further studies are required to investigate the digestibility and the nutritional effects expected from plant-based milk alternatives such as protein bioavailability, and the effects on human health compared to other animal milks.     

Functional and Sensory Properties of Salad Dressing Containing Fermented Peanut Milk

The effects of substituting peanut milk fermented with mixed cultures of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus for buttermilk on chemical, physical and sensory properties of ranch-style salad dressing were investigated. Increased amounts of fermented peanut milk in dressing resulted in decreased lightness, creamy flavor, oil emulsion capacity and consistency. Changes were dependent upon the commercial brand of dressing mix. Fermented peanut milk can be substituted for buttermilk in salad dressing at levels up to 25% without substantial reduction in sensory qualities.