草莓汁发酵乳饮料的研制

研制了一种以发酵乳和草莓汁为主要原料加工调制成的发酵乳饮料,在确定饮料所含发酵乳量（添加量定为35%）的基础上,阐述了草莓汁发酵乳饮料的生产工艺和最佳配方.得出最佳工艺配方为：发酵乳35%、草莓汁15%、白砂糖10%、复合稳定剂0.6%、酸液0.2%、适量的香精（均为质量分数）.     

草莓牛奶混合发酵酸乳加工工艺研究

以草莓和牛奶为主要原料,通过乳酸菌发酵,研究出草莓牛奶混合发酵酸乳。其最佳工艺参数为：草莓浓缩果汁用量为２０％,蔗糖、琼脂添加量分别为１０％和０．４％,接种量为６％,发酵温度４２℃,发酵时间６ｈ。     

发酵羊乳中乳酸菌低产粘菌株的筛选

对从商业乳酸菌发酵剂分离纯化的11株保加利亚乳杆菌和11株嗜热链球菌在发酵羊乳中的粘度进行了研究。结果表明,保加利亚乳杆菌L.b-124菌株和L.b-346菌株、嗜热链球菌S.t-222菌株和S.t-346菌株具有较低的产粘能力,凝乳时间也较短;将L.b-346菌株与S.t-346菌株按杆菌和球菌1:1比例混合后在43℃下发酵羊乳时,可获得较低的发酵粘度。     

羊乳与牛乳理化特性比较

以莎能奶山羊羊乳为样品,利用乳样自动分析仪,氨基酸自动分析仪、等离子发射光谱、色谱分析对其基本成分、氨基酸组成及含量进行了分析和检测,并与牛乳理化特性进行比较,为科学合理地利用羊乳,生产具有独特功能的羊乳制品提供了理论依据。     

Effects of ultraviolet irradiation on chemical and sensory properties of goat milk

Sensory and chemical consequences of treating goat milk using an UV fluid processor were assessed. Milk was exposed to UV for a cumulative exposure time of 18 s and targeted UV dose of 15.8 ± 1.6 mJ/cm². A triangle test revealed differences between the odor of raw milk and UV irradiated milk. Oxidation and hydrolytic rancidity was measured by thiobarbituric acid reactive substances and acid degree values (ADV). As UV dose increased, there was an increase in thiobarbituric acid reactive substance values and ADV of the milk samples. A separate set of samples were processed using the fluid processor but with no UV exposure to see if lipase activity and agitation from pumping contributed to the differences in odor. The ADV increased at the same rate as samples exposed to UV; however, sensory studies indicated that the increase of free fatty acids was not enough to cause detectable differences in the odor of milk. Solid phase microextraction and gas chromatography were utilized for the analysis of volatile compounds as a result of UV exposure. There was an increase in the concentration of pentanal, hexanal, and heptanal (relative to raw goat milk) after as little as 1.3 mJ/cm² UV dose. Ultraviolet irradiation at the wavelength 254 nm produced changes in the sensory and chemical properties of fluid goat milk.     

Probiotic Bifidobacterium animalis ssp. lactis Probio-M8 improves the properties and organic acid metabolism of fermented goat milk

The addition of Bifidobacterium to goat milk has dual effects on health, for which various inherent nutrients of goat milk are retained and live probiotics are provided. We explored the effect of Bifidobacterium animalis ssp. lactis Probio-M8 (Probio-M8) on fermentation characteristics, formation of organic acid, sensory properties, and storage characteristics of fermented goat milk (with added 4.0% sucrose). Addition of Probio-M8 decreased the fermentation time and significantly increased the content of functional organic acids, such as acetic acid, and functional long-chain unsaturated fatty acids, including linoleic acid, α-linolenic acid, and docosahexaenoic acid. Furthermore, the contents of medium-chain and short-chain fatty acids, which are related to “goaty” flavor, were significantly lower in the Probio-M8 treatment compared with the control. The number of living Probio-M8 decreased from 8.27 log cfu/mL (1.80 × 10⁸ cfu/mL) to 7.94 log cfu/mL (0.79 × 10⁸ cfu/mL) after 28 d of storage. Titratable acidity and pH value did not differ between the control group and experimental group (containing Probio-M8). Sensory evaluation indicated a lower goaty flavor and odor in the Probio-M8 fermented milk. Our results suggest that the addition of the probiotic Probio-M8 could improve the sensory, physicochemical, and functional properties of fermented goat milk.     

Short communication: Effect of the addition of Bifidobacterium monocultures on the physical,chemical, and sensory characteristics of fermented goat milk

The aim of the study was to use 3 monocultures of Bifidobacterium (Bifidobacterium animalis ssp. lactis AD600, Bifidobacterium animalis ssp. lactis BB-12, and Bifidobacterium longum AD50) in fermented goat milk to assess the microbial, physicochemical, rheological, and sensory quality of beverages during a 3-wk storage period at 5°C. The results indicated that selected bifidobacteria may be used for production of fermented goat milk because they comply with the minimum standards specified by the Food and Agriculture Organization of the United Nations and the World Health Organization during the entire period of storage. However, goat milk fermented by Bif. longum AD50 had less than 10⁶ cfu/g after 21 d of storage. The acidity, acetaldehyde content, viscosity, and hardness of fermented goat milk beverages depended on the strain and the storage period. Sensory properties were similar and acceptable, with a tendency for the quality to be reduced with an extended storage time. Depending on the monoculture of bifidobacteria used to manufacture fermented goat milk, the product had a different pH value. Titratable acidity in all fermented goat milk increased significantly along with the time of storage. Our study has shown that monocultures of bifidobacteria had a significant effect on the content of acetaldehyde, but the lowest effect over the entire storage period was observed in goat milk fermented by Bif. animalis ssp. lactis BB-12. This sample also had the lowest viscosity values compared with other samples and the best organoleptic properties during a 3-wk storage period.     

Autochthonous adjunct culture of Limosilactobacillus mucosae CNPC007 improved the techno-functional,physicochemical, and sensory properties of goat milk Greek-style yogurt

We evaluated the performance of Limosilactobacillus mucosae CNPC007 as an autochthonous adjunct culture in the production of goat milk Greek-style yogurt. The techno-functional, physicochemical, and sensory characteristics of the control yogurt (containing only starter culture, CY) and the probiotic yogurt (with the probiotic strain added, PY) were assessed during 28 d of refrigerated storage. Furthermore, we determined the survival of the strain throughout the gastrointestinal tract under simulated conditions. The PY yogurt had a lower extent of proteolysis index and a higher depth of proteolysis index. These results indicate that the proteolytic enzymes of L. mucosae may have a possible action in PY. The PY formulation exhibited viscosity almost 1.5 times as high as CY over the refrigeration period, probably due to higher production of exopolysaccharides by the probiotic strain, which directly interferes with the microstructure, texture, and viscosity of the product. The PY formulation received higher scores for color, flavor, and global acceptance at 1 d of storage and higher texture scores at 28 d. The counts of L. mucosae remained high (>7 log cfu/g and >8.5 log cfu/g) throughout mouth-ileum digestion and storage, respectively, in PY. The autochthonous adjunct culture of L. mucosae CNPC007 can be used for production of a novel potentially probiotic goat yogurt without negatively affecting the general characteristics of the product quality, adding value associated with maintaining its functional potential.     

乳酸菌与酵母菌对牦牛酸乳品质形成的影响

为明确乳酸菌和酵母菌在牦牛酸乳品质形成中发挥的作用,以牦牛乳粉为原料、牦牛酸乳为发酵剂发酵酸乳,在发酵过程中分别抑制乳酸菌和酵母菌的活性,测定并比较正常发酵、抑制乳酸菌发酵、抑制酵母菌发酵酸乳的风味、口感、质构等相关指标。结果表明,乳酸菌和酵母菌对牦牛酸乳品质形成均起到关键作用,乳酸菌对酸乳酸度、质构、氨基酸态氮、有机酸、V_(B1)及酮类和酸类风味物质的贡献较大,酵母菌对乙醇、V_(B2)及醇类和酯类风味物质的贡献较大。     

高效液相色谱法测定传统发酵乳中的有机酸组成

利用高效液相色谱(HPLC)法研究了传统发酵乳中的7种有机酸的分离测定条件,同时对青海省传统发酵乳酸牦牛奶、酸山羊奶和酸马奶等40个样品的乳酸、乙酸和柠檬酸含量进行了测定。结果表明,选择浓度为0.010 mol/L磷酸—磷酸二氢钠(pH=2.0)和甲醇(体积比为98︰2)做流动相,流速为0.5 mL/min,紫外检测波长为210 nm时可以较好地分离测定发酵乳中的乳酸、乙酸和柠檬酸。该方法不仅相对标准偏差小(0.35%～1.23%),回收率高(95.4%～103.8%),线性相关系数高(乳酸r>0.99994,醋酸r>0.99997,柠檬酸r>0.99999),而且具有较高的准确度和精确度;通过发酵乳样品的有机酸含量测定发现,发酵乳中除主要含有乳酸外还有微量的乙酸、柠檬酸和痕量的甲酸、苹果酸、琥珀酸及丙酸。3种家畜奶发酵乳中各种有机酸含量有较大差别。     

Physicochemical,textural and volatile characteristics of fermented milk co-cultured with Streptococcus thermophilus,Bifidobacterium animalis or Lactobacillus plantarum

Fermented milks were prepared with various culture combinations of Lactobacillus plantarum or Bifidobacterium animalis with Streptococcus thermophilus, and the impact of microbes combinations on acidification, proteolysis, lipolysis, texture, volatiles and sensory quality of fermented milk was investigated during 21-day storage at 4 °C. The results showed that products from the co-cultures displayed higher titratable acidity, more peptides, higher proteolytic activity and lipolysis capacity compared with that from the pure strains of S. thermophilus. When L. plantarum and B. animalis combined in a ratio of 2:1 with S. thermophilus, the products maintained relatively more viable cell counts of the 3 strains, strong proteolysis ability and lipolysis capacity during the storage. Milk fermented by co-cultures of the 3 strains exhibited higher cohesiveness, more volatiles and better sensory quality compared with these fermented by S. thermophilus only or in co-cultures with either B. animalis or L. plantarum based on principal component analysis.     

酶法生产草莓汁的研究

研究了直接榨汁、解冻后榨汁、纤维素酶酶解、果胶酶酶解四种方法对生产草莓汁品质的影响,结果表明,果胶酶酶解生产草莓汁效果最佳。通过正交实验研究了酶加入量、酶解温度、酶解时间对草莓汁出汁率、花色苷及Vc的影响。结果表明,果胶酶制取草莓汁的最佳工艺是:酶加入量0.005%、酶解时间1h、酶解温度50℃。此条件下生产的草莓汁色泽鲜艳、营养丰富,而且美味可口。      

山羊乳与绵羊乳的物理化学性质比较

阐述了山羊乳与绵羊乳在物理化学方面的不同特性，比较了它们在色泽、风味以及化学组成方面的不同，如它们的脂肪、非脂固形物、蛋白质、乳糖、灰分、维生素含量等。对蛋白质和脂肪而言，还进一步讨论了它们的氨基酸和脂肪酸组成。     

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.     

Inoculum size of co-fermentative culture affects the sensory quality and volatile metabolome of fermented milk over storage

Lacticaseibacillus paracasei PC-01 is a probiotic candidate isolated from naturally fermented yak milk in Lhasa, Tibet, and it has been shown to possess excellent milk fermentation properties. This study used Lacticaseibacillus paracasei PC-01 as a co-fermentation strain to investigate the effect of inoculum size with a commercial starter in milk fermentation on the product flavor and profile of volatile metabolites over 28 d of cold storage. Lacticaseibacillus paracasei PC-01 was allowed to ferment in pasteurized milk with or without the commercial starter (YF-L904) at 42°C until the pH decreased to 4.5. The finished fermented milks were stored at 10°C for 28 d. Milk samples were taken at hour 0 (before fermentation) and then at d 1, 14, and 28 of cold storage. Different inoculum sizes of Lacticaseibacillus paracasei PC-01 had no significant effect on pH or titratable acidity during storage of fermented milk. Viable counts of strain PC-01 continued to increase during cold storage of the fermented milk. Generally, as storage of fermented milk proceeded, the overall sensory quality score decreased in all groups. However, the overall sensory scores of PC-01-M were generally higher than those of other groups, suggesting that a medium dose of Lacticaseibacillus paracasei PC-01 had the most obvious effect of slowing the decline in sensory quality of fermented milk during storage. Changes in sensory scores and consumer preferences were accompanied by increases in both the quantity and variety of key volatile metabolites in fermented milk during fermentation, post-ripening (d 1), and storage. Major differentially abundant metabolites, including acetaldehyde, methyl ketones, medium-chain and short-chain fatty acids, 2,3-butanedione, and acetoin, were enriched in fermented milks rated highly in the sensory evaluation. Our data confirmed that the inoculum size of co-fermentative culture affected the sensory quality and volatile metabolome of fermented milk over storage, and an optimal range of co-fermentative culture was titrated in this work.     

无糖藜麦发酵乳的物化特性及抗氧化活性

目的：开发有益于身体健康的无糖风味发酵乳。方法：在复原乳中添加藜麦浆,以木糖醇替代蔗糖经发酵后得无糖藜麦发酵乳,以酸度、黏度、持水力等物化特性及体外抗氧化为评价指标,探究藜麦浆对无糖发酵乳的影响。结果：添加藜麦浆的发酵乳pH高于普通发酵乳,酸度、黏度、持水力则略低于普通发酵乳,且无糖藜麦发酵乳的DPPH自由基清除率（86.23%）、ABTS自由基清除率（71.32%）、羟基自由基清除率（63.27%）、Fe³⁺还原能力（0.48 mmol/L）均高于普通发酵乳。结论：添加木糖醇和藜麦浆会改变发酵乳的物化性质,同时提高发酵乳的抗氧化活性。     

毛酸浆对酸羊奶感官品质的影响

以毛酸浆水提取物和羊奶为原料,采用Box-Benhnken响应面法对酸羊奶的最佳发酵工艺参数进行了优化,利用电子鼻分析了毛酸浆的添加对产品感官品质的影响。结果提示,毛酸浆对产品的感官品质影响显著,与羊奶可以产生协同增香的效果,与原味酸羊奶相比具有一定的抗氧化性。通过响应面优化所得的毛酸浆酸羊乳最佳发酵工艺参数为:毛酸浆提取物添加量7.5%,发酵剂添加量6.5%,43℃下发酵7 h。经此工艺制备的酸羊乳,提高了产品的营养价值,是一种颇具前途的功能性酸羊奶。      

固相微萃取技术(SPME)分析羊奶中挥发性化合物

采用固相微萃取技术（SPME）提取羊奶中的挥发性化合物,经气相色谱质谱联用仪进行测定分析,实验结果表明,羊奶中挥发性化合物共检测到42种,主要成分为挥发性脂肪酸,酯类、醇和酮类,还含有一些其他挥发性化合物。其中挥发性脂肪酸有10种,主要由短链脂肪酸和中等长度碳链脂肪酸组成。酯类物质有16种,主要包括邻苯二甲酸二丁酯、邻苯二甲酸二乙酯、14-甲基-十五酸甲酯和己二酸二（2-乙基）乙酯等。另外挥发性醇类和酮类物质共7种,其它挥发性化合物9种。      

陕西生鲜羊奶及其加工羊奶粉品质调研分析及相关性研究

为调查陕西省生鲜羊奶及羊奶粉品质随月份的变化规律,明确生鲜羊奶和羊奶粉品质之间的相关关系,该研究以2020年4月至11月某乳品企业在陕西不同地区的奶站收购的生鲜羊奶及其加工羊奶粉为试验样品,对其感官、理化和安全指标进行分析.结果表明,生鲜羊奶和羊奶粉在感官指标方面均符合国家标准要求;在理化指标方面,生鲜羊奶脂肪含量为3...