鱼精蛋白对延长鱼糕制品有效保存期的作用

本文用鱼精蛋白、苯甲酸钠和山梨酸钾分别添加在鱼糕制品中，并于12℃和24℃条件下保存，观察其保存效果。结果表明：添加0．8％鱼精蛋白的鱼糕在12℃和24℃的有效保存期分别为7d和5d，达到添加0．3％苯甲酸钠和0．2％山梨酸钾的效果。     

蜂胶对鸡蛋保鲜作用的研究

研究了蜂胶对鸡蛋表面常见菌的抑制作用及其对鸡蛋的保鲜效果,实验结果表明,蜂胶可在大肠杆菌,枯草芽胞杆菌,无恒谱形杆菌,荧光假单胞菌及沙门氏菌的培养平板上形成抑菌圈;1％的蜂胶平板可完全抑制以上五种细胞的生长,实验还表明蜂胶对鸡蛋表面混合菌有明显的抑制作用;鸡蛋保鲜实验结果表明：1．5％的蜂胶溶液即可对鸡蛋的保鲜产生显著的效果。     

鲜切芹菜加工关键技术的研究

鲜切蔬菜是一种新型的蔬菜加工产品。本实验对护色保鲜、保脆等加工关键技术进行了研究．分别采用不同浓度的苯甲酸钠、维生素C、氯化钙溶液及混合溶液对鲜切后的芹菜进行保鲜处理．通过对试验结果的分析得出：采用0．05％苯甲酸钠、0．05％维生素C、0.3％氯化钙复合护色保鲜液处理的芹菜．经包装后在4℃冷藏能得到较好的保鲜效果。     

气调包装及天然保鲜剂对泠却鲜猪肉的保鲜效果研究

对冷却鲜猪肉分别用保鲜剂(含乳酸钠5％、异维生素C钠0．2％和乙酸0．4％的混合保鲜溶液)处理加PE塑料袋包装、PF/PA塑料袋气调包装(25％CO2、25％N2和50％O2混合气体)和保鲜剂处理加PF/PA塑料袋气调包装，与PE塑料袋包装对照，研究其在0～4℃冷却保存条件下不同处理方法的保鲜效果。每隔2d对猪肉进行感官评定、测定其TVB-N值、菌落总数，并进行球蛋白沉淀试验，以判定猪肉新鲜度的变化。结果表明：PE／PA塑料袋气调包装和保鲜剂处理均明显延长冷却鲜猪肉的保存期，可使其保存期分别达到12d和9d：两者同时应用效果更好，可使冷却鲜猪肉的保存期达到15d以上；气调包装的冷却保存猪肉颜色始终保持鲜红状态；课题组自主设计、制造的气体比例混合器，用于冷却肉的气调包装，保鲜效果优良。     

益生菌在酸奶生产过程中对酵母和霉菌污染的控制

以商业生物保鲜菌(干酪乳杆菌)作参照,研究益生菌Laaobacillus casei Zhang在酸奶发酵和贮藏期间对酵母和霉菌污染的控制,及其对酸奶品质的影响.结果表明:酸奶中添加3.00× 106 g-1的L.casei Zhang,能防止酵母和霉菌的污染,具有延长酸奶保质期的效果,且抑菌效果高出商业生物保鲜菌50％.此外,添加L.casei Zhang最多缩短发酵时间1h,减缓酸奶后酸化程度,不影响酸奶贮藏期内酸度、黏度和持水性等.L.casei Zhang具有作为生物保鲜菌的优良特性,可应用于酸奶制品的工业化生产.     

延长酸奶保存期的研究

冻藏能使酸奶的保存期延长１１天以上（３－１４天）；配料时加入１２％－１６％白砂糖的酸奶冻藏后可当冰淇淋吃，但在溶化后又可当酸奶喝。     

球杆菌比例、固形物含量和灌装方式对酸奶保存期的影响

选用球杆菌比例、非脂乳固形物含量和灌装方式对酸奶的保存期进行了研究。结果表明:球杆菌比例为1.5∶1(S.t∶L.b=1.5∶1)、非脂乳固形物含量为12.3%,采用无菌灌装方式生产的酸奶,在冷藏条件下可保存24d,此时乳酸菌活菌数在6.0×108mL-1以上,比普通酸奶延长保存期15d。若采用球杆菌比例为2∶1、非脂乳固形物含量为15.3%,无菌灌装的酸奶可冷藏32d。     

荸荠功能组分在马蹄糕防腐保鲜中的应用初探

用滤纸片法考察了荸荠功能组分BQ的抑菌谱，通过测定马蹄糕中菌落总数的变化，研究BQ在马蹄糕中的保鲜效果。结果表明，BQ有较强的抑菌能力，对细菌的抑制能力大于霉菌和酵母菌。在马蹄糕中，BQ添加量大于0．1％的时候其防腐保鲜效果已经可以较为明显的看出。当添加量为0．5％时，已经和0．1％的山梨酸钾的防腐保鲜能力相当，能将马蹄糕的保质期延长至7d。并且对马蹄糕常出现的腐斑、胀气及出水等品质问题都有不同程度的改善，而且添加浓度与品质有着较好的量效关系。     

净菜保鲜剂选用的研究

主要研究上海青、香菜和油麦菜的保鲜技术,通过正交实验确定了在0～8℃时保鲜剂的最佳配方,结果如下:对于上海青,保鲜刺最佳配方为柠檬酸0.08%,氯化钙0.05%,苯甲酸钠0.10%;对于香菜,保鲜荆最佳配方为柠檬酸0.08%.氯化钙0.10%,苯甲酸钠0.05%;对于油麦菜,保鲜荆最佳配方为柠檬酸0.08%,氯化钙0.10%,苯甲酸钠0.05%.实验表明,通过保鲜剂处理可以明显延长净菜贮藏期.     

羧甲基淀粉作酸奶稳定剂的应用效果研究

对羧甲基淀粉作为酸奶稳定刺及其应用效果进行了分析研究。结果表明：蔗糖添加8％，发酵温度为42℃，菌种比例为St：Lb=1．5：1的前提下，通过正交试验筛选出最佳发酵工艺条件为CMS添加0．1％、发酵时问为4h、接种量为3％．在4℃的保存条件下，添加CMS的酸奶比对照组酸奶的保质期至少延长了2d。     

Effects of polymerized goat milk whey protein on physicochemical properties and microstructure of recombined goat milk yogurt

Goat milk whey protein concentrates were manufactured by microfiltration (MF) and ultrafiltration (UF). When MF retentate blended with cream, which could be used as a starting material in yogurt making. The objective of this study was to prepare goat milk whey protein concentrates by membrane separation technology and to investigate the effects of polymerized goat milk whey protein (PGWP) on the physicochemical properties and microstructure of recombined goat milk yogurt. A 3-stage MF study was conducted to separate whey protein from casein in skim milk with 0.1-µm ceramic membrane. The MF permeate was ultrafiltered using a 10 kDa cut-off membrane to 10-fold, followed by 3 step diafiltration. The ultrafiltration-diafiltration-treated whey was electrodialyzed to remove 85% of salt, and to obtain goat milk whey protein concentrates with 80.99% protein content (wt/wt, dry basis). Recombined goat milk yogurt was prepared by mixing cream and MF retentate, and PGWP was used as main thickening agent. Compared with the recombined goat milk yogurt without PGWP, the yogurt with 0.50% PGWP had desirable viscosity and low level of syneresis. There was no significant difference in chemical composition and pH between the recombined goat milk yogurt with PGWP and control (without PGWP). Viscosity of all the yogurt samples decreased during the study. There was a slight but not significant decrease in pH during storage. Bifidobacterium and Lactobacillus acidophilus in yogurt samples remained above 10⁶ cfu/g during 8-wk storage. Scanning electron microscopy of the recombined goat milk yogurt with PGWP displayed a compact protein network. Results indicated that PGWP prepared directly from raw milk may be a novel protein-based thickening agent for authentic goat milk yogurt making.     

The effect of inulin as a fat replacer on the quality of set-type low-fat yogurt manufacture

The influence of different levels of inulin on the quality of fat-free yogurt production was investigated. Inulin was added to milk containing 0.1% of milk fat to give inulin levels of 1, 2 and 3%. The experimental yogurts were compared with control yogurt produced from whole milk. The total solids content of milk was standardized to 14% by adding skim milk powder to the experimental yogurt. The chemical composition, pH, titratable acidity, whey separation, consistency, acetaldehyde and volatile fatty acidity contents were determined in the experimental yogurts after 1, 7 and 15 days. Sensory properties of the yogurts were evaluated during storage. The addition of inulin at more than 1% increased whey separation and consistency. Acetaldehyde, pH and titratable acidity were not influenced by addition of inulin. Tyrosine and volatile fatty acidity levels were negatively affected by inulin addition. With respect to the organoleptic quality of yogurt, inulin addition caused a decrease in organoleptic scores: the control yogurt had the highest score, and the lowest score was obtained in yogurt samples containing 3% of inulin. Overall, the yogurt containing 1% of inulin was similar in quality characteristics to control yogurt made with whole milk.     

木糖醇南瓜酸奶的工艺研究

采用南瓜浆、木糖醇与原乳混合进行乳酸菌发酵制成木糖醇南瓜酸奶,并对其工艺进行优化。通过单因素试验选取南瓜浆、木糖醇及复合稳定剂的添加量为3个因素,进行正交试验确定最佳工艺参数。试验结果表明,南瓜浆的添加量7.5%,木糖醇的添加量8.0%,复合稳定剂的添加量0.4%,发酵剂的添加量4.0%,发酵时间4 h,发酵温度42℃,此工艺条件下制作的木糖醇南瓜酸奶酸甜适度,口感细腻,香味浓郁。     

紫米酸奶的工艺优化及贮藏品质分析研究

以熟紫米粉和鲜牛奶为主要原料，研制具有抗氧化性能的紫米酸奶。将紫米酸奶的酸度、持水力和感官评分作为评价指标，在单因素试验基础上，利用响应面分析法对紫米酸奶的工艺进行优化，并对紫米酸奶的贮藏品质进行了研究。结果表明，紫米酸奶的最佳工艺为紫米粉添加量22 g/L，白砂糖添加量7%，接种量0.06%。在此优化条件下，紫米酸奶的感官评分为91.1分。在贮藏期间，紫米酸奶的感官评分、持水力、pH、酸度、乳酸菌数及对1,1-二苯基-2-三硝基苯肼（DPPH）自由基的清除率明显优于对照组。紫米酸奶具有更长的货架期和较强的抗氧化能力。     

双歧杆菌酸奶生产工艺的优化

通过研究婴儿双歧杆菌和长双歧杆菌在脱脂乳中的生长特性、影响其发酵的因素以及发酵方式 ,优化出双歧杆菌酸奶的最佳生产工艺。研究结果显示 ,选用长双歧杆菌制作酸奶时 ,在乳中添加 0 3 %酵母粉 ,低聚糖取代 10 %的蔗糖 ,接菌量为 10 % ;选用婴儿双歧杆菌制作酸奶时 ,在乳中添加 0 6%的酵母粉 ,以低聚糖取代 2 0 %的蔗糖 ,接菌量为 15 %。 3 9℃条件下发酵 ,然后再按 1∶1的比例与普通酸奶混合 ,所制得的酸奶在贮存期间 ,活菌数可达到10 8cfu/mL以上。     

紫薯酸奶的研制

以鲜牛奶,新鲜紫薯为主要原料,添加嗜热链球菌和保加利亚乳杆菌,研究搅拌型紫薯酸奶的加工工艺条件。通过单因素试验和正交试验确定制作紫薯酸奶的最佳工艺参数。结果表明,紫薯与鲜牛奶的比例为1∶4,接种量为4%,发酵温度37℃,发酵时间为12 h,白砂糖添加量为9%。此条件下制作的酸奶呈淡紫色,质地均匀一致,具有紫薯和浓郁的乳酸菌发酵酸奶的香味,酸甜可口,口感细腻,柔和。     

Physiochemical Properties,Microstructure, and Probiotic Survivability of Nonfat Goats’ Milk Yogurt Using Heat‐Treated Whey Protein Concentrate as Fat Replacer

There is a market demand for nonfat fermented goats’ milk products. A nonfat goats’ milk yogurt containing probiotics (Lactobacillus acidophilus, and Bifidobacterium spp.) was developed using heat‐treated whey protein concentrate (HWPC) as a fat replacer and pectin as a thickening agent. Yogurts containing untreated whey protein concentrate (WPC) and pectin, and the one with only pectin were also prepared. Skim cows’ milk yogurt with pectin was also made as a control. The yogurts were analyzed for chemical composition, water holding capacity (syneresis), microstructure, changes in pH and viscosity, mold, yeast and coliform counts, and probiotic survivability during storage at 4 °C for 10 wk. The results showed that the nonfat goats’ milk yogurt made with 1.2% HWPC (WPC solution heated at 85 °C for 30 min at pH 8.5) and 0.35% pectin had significantly higher viscosity (P < 0.01) than any of the other yogurts and lower syneresis than the goats’ yogurt with only pectin (P < 0.01). Viscosity and pH of all the yogurt samples did not change much throughout storage. Bifidobacterium spp. remained stable and was above 10⁶CFU g^‐1 during the 10‐wk storage. However, the population of Lactobacillus acidophilus dropped to below 10⁶CFU g^‐1 after 2 wk of storage. Microstructure analysis of the nonfat goats’ milk yogurt by scanning electron microscopy revealed that HWPC interacted with casein micelles to form a relatively compact network in the yogurt gel. The results indicated that HWPC could be used as a fat replacer for improving the consistency of nonfat goats’ milk yogurt and other similar products.     

Influence of potassium sorbate on the growth of yeasts and moulds in yogurt

Yeasts and moulds are little affected by low pH and may cause spoilage of yogurt during storage. In the present study, potassium sorbate was added as a preservative in concentrations of 0.05%, 0.1% and 0.2%. The unpreserved yogurt showed unfavourable characteristics: yeast and mould counts and acidity increased. The addition of potassium sorbate, however, inhibited yeast and mould levels, with normal characteristic properties extending more than 14 days. Potassium sorbate is thus seen as valuable for preserving yogurt.     

搅拌型酸奶后酸化控制的初步研究

文中针对搅拌型酸奶成熟后在贮存、运输、销售、食用前出现的后酸化现象(postacidification)文中进行了初步研究。在无水乙醇抑制后酸化的实验中,4%的无水乙醇能明显抑制乳酸菌的进一步产酸,且不影响其优良的感官指标。进一步研究发现,每40mL酸奶制品分别添加1.4mL酒精度为38%的汾酒、1.0mL酒精度为62%的高度酒均可明显抑制后酸化现象。文中还尝试了酵母菌抑制后酸化的效果,结果发现,1株从牧区家庭自制酸奶中分离的酵母菌以2.0×107个/mL的浓度,每40mL酸奶制品添加0.1mL不仅可抑制后酸化现象,而且轻微的乙醇发酵改善了酸奶的口味,提高了酸奶的感官品质。经细胞形态、菌落特征、生理生化及产孢子类型可初步判断该酵母菌为异酒香酵母。     

添加酪蛋白水解肽改善酸乳的加工特性

向牛乳中添加不同含量菠萝蛋白酶酪蛋白水解肽（0.1%、0.3%、0.5%）,测定酸乳发酵及冷藏过程中理化、微生物和风味指标变化。结果表明,添加酪蛋白水解肽（casein hydrolytic peptides,CHP）加快了酸乳发酵后期pH值下降,缩短发酵时间;CHP添加量为0.1%时发酵时间较对照组缩短了34 min。微流变测定表明,添加CHP降低了发酵后期酸乳的弹性指数（elasticity index,EI）和流动性指数（fluidity index,FI）,但宏观黏度指数（macroscopic viscosity index,MVI）有所升高。扫描电镜图像显示,各组酸乳样品均呈多孔网状结构,适量添加CHP（0.1%）可以改善酸乳的胶体结构,使酸乳网络结构更致密均匀。酸乳冷藏期间,添加CHP可以提高发酵剂菌株的活菌数,一定程度地促进酸类、醛类和酮类等风味化合物的形成,添加0.3%的CHP降低了酸乳EI;随着CHP添加量的增加（0.3%、0.5%）,酸乳的硬度及胶着性逐渐下降,但对持水力、内聚性及黏性无明显影响。本研究为CHP在酸乳加工中的应用及产品品质和功能性提升提供技术参考。