Effect of rice fat mimics on texture and microstructure of low-fat yoghurt

This paper made a research on a new kind of rice fat mimics, which was obtained from rice powder hydrolyzed by α-amylase. Through the comparison between the yoghurt added with diverse proportions of above mentioned rice fat mimics and the reduced-fat yoghurt without any fat mimics as well as full-fat ones, the effect of the rice fat mimics in different proportions was examined upon the composition, the microstructure, the texture and the sensory evaluation of reduced-fat yoghurt. The results showed that the yoghurts added with rice fat mimics exhibited similar organoleptic attribute, textual characteristics and acceptability compared to those of full-fat controls （P〉0.05）, but with lower fat content and looser microstructures.

Evaluation of Total Fatty Acid Profiles of Two Types of Low-Fat Goat Milk Ice Creams

Effects of frozen-storage on fatty acids profiles and basic nutrient contents of two types of low-fat caprine milk ice creams were investigated during 0, 2, 4, 8 weeks of storage at -18°C. Two types of the experimental low-fat soft-serve goat ice creams were manufactured using whole (full-fat) milk and 2% fat goat milk with addition of commercial powdered vanilla flavor pre-mix containing 0.25% fat (Alpha Freeze, D466-A9047, Tampa, FL, USA). Fatty acid concentrations were quantified using a Thermo Electronic gas chromatography (GC)-MS (Model TRACE GC Ultra, Austin, TX, USA) equiped with an automatic sampler (Model AS-3000, Thermo Electronic Co.). The results showed that fat content was the only basic nutrient component exhibited the difference between the two types of ice creams, while no other components have shown differences between the two low-fat ice creams during the storage periods. The level of lauric acid (C12:0) was the highest among all 16 fatty acids, followed by palmitic (C16:0), linoleic (C18:1), and myristic acid (C14:0). The high levels of the medium chain fatty acids (C12:0 and C14:0) might have been derived from the goat milk as well as the palm oil asa part of the ingredients in the commercial ice cream premix. Among long chain fatty acids, palmitic acid (C16:0) was the highest, followed by oleic acid (C18:1) and stearic acid (C18:0). All of the long chain fatty acids contents were significantly higher (P < 0.05 or 0.01) in whole milk ice cream than those in 2% fat ice cream, except for the C22:0 and C24:00 acids. It was concluded that mean levels of the individual fatty acids in the caprine ice creams were significantly influenced by the types of milk fat used in the ice creams, but not by storage periods and storage × fat type interaction effects.

Comparison of free fatty acid composition between low-fat and full-fat goat milk cheeses stored for 3 months under refrigeration

Differences in free fatty acid (FFA) compositions between low-fat (LF) and full-fat (FF: whole milk) goat cheeses were evaluated during 3 months at 4oC refrigeration. The two types of cheeses were manufactured using a bulk milk from the mixed herd of Saanen, Alpine, and Nubian goat breeds. LF cheeses were made using LF milk after cream separation. FFAs of all cheeses were extracted in diisoprophyl ether using polypropylene chromatography column, and FFA concentrations were quantified using a gas chromatograph equipped with a fused silica capillary column. Moisture, fat, protein contents (%) and pH of fresh LF and FF cheeses were: 55.1, 52.3;1.30, 25.6;35.7, 22.5;5.40, 5.42, respectively. The FFA contents (mg/g cheese) of fresh FF and LF cheeses prior to storage treatments for C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C16:0, C18:0, C18:1, and C18:2 were: 0.020, 0.072;0.070, 0.035;0.061, 0.055;0.181, 0.167;0.073, 0.047;0.174, 0.112;0.579, 0.152;0.308, 0.202;0.521, 0.174;and 0.057, 0.026, respectively. The respective FFA to total fatty acid ratios for 0, 1 and 3 months aged FF and LF cheeses were 8.44, 12.4;6.31, 16.91;12.03, 14.19. The LF cheeses generated more FFA than FF cheeses, while actual FFA content in FF cheese was significantly higher than in LF cheese. The FFA contents of LF cheese at 0, 1 and 3 months storage were 48.0, 96.8 and 36.4% of those of FF cheese, respectively. It was concluded LF cheese generated higher amount of FFA than FF cheese, although total FFA content was significantly (P<0.05) lower in LF cheese than in FF cheese.

Production of Low Fat Cheddar Cheese Made Using Exopolysaccharide-Producing Cultures and Selected Ripening Cultures

Low fat cheeses often suffer from undesirable texture and flavor. The objective of this study is to improve the yield, texture, flavor and quality of low fat Cheddar cheese during ripening using exopolysaccharide-producing lactobacilli and ripening cultures. The article represents one of the first attempts to tackle both texture and flavor at the same time. The study reveals the effect of aging on the texture and flavor of low fat Cheddar cheese over a ripening period of six months. The cheese manufactured with a modified protocol using EPS-producing cultures and ripening cultures showed higher values for moisture content (45%) and yield (9.4%) when compared to cheese manufactured with the conventional procedure and without the addition of EPS-producing cultures and ripening cultures (37.7%) and (4.9%) respectively. The obtained results indicated a 70% decrease in the fat content of the cheese. Texture profile analysis (TPA) indicated that the hardness, the cohesiveness, the springiness, the gumminess and the chewiness of the cheeses made using the EPS-producing cultures decreased with aging. The texture of the ripened low fat cheese made using EPS-producing cultures was described as chewy, springy, cohesive and smooth. The use of the ripening cultures resulted in the elimination of the bitter flavor defect which is a common problem in low fat Cheddar.

Analysis of Low Melting Point Fat Constituents of Black Soybeans by HS-SPME-GC-MS

[Objectives] To analyze the low melting point fat constituents in the black soybeans with green and yellow heart and their relative content,and compare the differences in the low melting point fat constituents between different kinds of black soybeans. [Methods] Using HS-SPME-GC-MS,the qualitative analysis was performed on the low melting point fat constituents of black soybeans; using peak area normalization method,the relative content of constituents was calculated. [Results]A total of 42 peaks were identified from the low melting point fat constituents of the black soybeans with yellow heart,and 18 kinds of chemical constituents were identified,accounting for 81.39% of total relative content of low melting point fat constituents; a total of 37 peaks were identified from the low melting point fat constituents of the black soybeans with green heart,and 15 kinds of chemical constituents were identified,accounting for 83.24% of total relative content of low melting point fat constituents. There were 9 kinds of common chemical constituents for the two kinds of black soybeans,and 5-allylguaiacol had the highest relative content,followed by hexanol. [Conclusions] There was no significant difference in the low melting point fat constituents between two kinds of black soybeans.

Low saturated fat diet is effective in trigeminal neuralgia

Objective: To determine the effectiveness of low saturated fat diet (LSFD) in patients with trigeminal neuralgia (TN). Design: 1) Internet forum where patients could request a 10 page LSFD plan, and 2) Follow-up assessment done by a retrospective 20-item questionnaire. Duration of treatment—2 months to 13 years. Pain rated on a Visual Analogue Scale and reported as typical, atypical, or both, defining typical TN as intermittent quick jolts/stabbing pain and atypical TN as continuous never ending discomfort. Setting: General community. Patients: 55 unselected patients, most with unilateral, severe and daily symptoms in V2 and V3 distribution for a mean duration of 8 years and on medications. 84% had pain level 9-10 before treatment, 89% had daily attacks and 31% had undergone surgical procedures. Intervention: LSFD for 2 months-13 years (mean 20 months). Main outcome measure: VAS score and medication use before and after LSFD treatment. Results: Reported SF content was 3-25 gm. With treatment 96% typical TN (p Conclusions: LSFD is effective in TN with high compliance, few adverse effects and may result in reduction/ elimination of medications even in most severe cases.

低鱼粉高脂饲料添加大豆卵磷脂对黄鳝生长、血清生化指标及肠道菌群的影响

试验旨在研究低鱼粉高脂饲料中添加大豆卵磷脂对黄鳝(Monopterusalbus)生长、血清生化指标及肠道菌群的影响,为降低黄鳝鱼粉使用量提供依据。以初始体重(20.03±0.01)g黄鳝为研究对象,以含有42%鱼粉、22%豆粕、6%粗脂肪的饲料为正常鱼粉组,另以含有22%鱼粉、52%豆粕和9%粗脂肪的饲料为低鱼粉高脂组,分别在低鱼粉高脂组中添加1%和2%的大豆卵磷脂,进行为期56d的养殖试验,于室外池塘进行网箱养殖,日投喂1次,喂量为黄鳝体重3%—5%。结果表明:(1)与对照组相比,低鱼粉高脂组黄鳝增重率显著降低(P<0.05),饵料系数与肝体比均显著增加(P<0.05),但添加2%大豆卵磷脂后黄鳝增重率显著提高(P<0.05),而饵料系数与肝体比显著降低(P<0.05);(2)对比正常鱼粉组,低鱼粉高脂饲料组黄鳝血清甘油三酯、总胆固醇、高密度脂蛋白、低密度脂蛋白、血氨、尿素氮、谷草转氨酶、谷丙转氨酶、酸性磷酸酶与免疫球蛋白M含量显著增加(P<0.05),且碱性磷酸酶活性显著降低(P<0.05),而添加2%大豆卵磷脂使黄鳝血清的高密度脂蛋白含量与碱性磷酸酶活性显著增加(P<0.05),低密度脂蛋白、血氨、尿素氮、谷草转氨酶、谷丙转氨酶、酸性磷酸酶与免疫球蛋白M水平显著下降(P<0.05);(3)与对照组相比,低鱼粉高脂组黄鳝后肠绒毛高度与杯状细胞显著降低(P<0.05),而添加2%大豆卵磷脂后黄鳝后肠绒毛高度与杯状细胞数目上升;(4)与对照组相比,低鱼粉高脂组不动杆菌属与考克氏菌属相对丰度上升,而与低鱼粉高脂组相比,添加2%大豆磷脂后黄鳝肠道群落的丰富度与多样性显著增加(P<0.05),且显著提高了肠道红杆菌属的相对丰度,并显著减少不动杆菌属与考克氏菌属的丰度(P<0.05)。由此得出,在试验条件下,2%大豆卵磷脂可促进脂肪代谢和提高机体免疫性能,并修复肠道组织结构与维持菌群稳态,进而缓解低鱼粉高脂饲料对黄鳝生长的负面影响。

蛋清蛋白微粒基低脂沙拉酱流变学特征及品质优化

本实验以蛋清蛋白微粒(egg white protein microparticles,EWPM)为代脂基质,研究EWPM/黄原胶(xanthan gum,XG)共混质量分数、pH值、氯化钠含量、糖含量、均质条件等对超低脂沙拉酱产品流变学特性的影响规律。研究发现,XG对EWPM基超低脂沙拉酱具有显著的增稠效果,然而含量过高会导致低脂沙拉酱恢复性下降。基础调味组分对超低脂沙拉酱品质的影响存在较大差异,pH值和盐对体系黏度影响较大,糖添加量对黏度的影响相对较小。适度的胶体磨均质转速和均质时间可以减小产品的粒径,增加其内部均一性,显著提高产品的整体黏度。本实验以沙拉酱流变学行为调控为重点,为低脂沙拉酱的研究提供一个更加明确的工艺优化方向。

基于压榨法优化低脂芝麻酱加工工艺

通过压榨法制作的芝麻酱,脂肪含量较低,但黏稠度偏高,所以需要在低脂芝麻酱中添加脂肪替代物,另外,再添加一定量的乳化剂,以减少低脂芝麻酱的分层现象。通过单因素试验和响应面试验对芝麻酱的感官评分进行研究和分析,结果表明各因素对芝麻酱感官评分的影响次序是黄原胶添加量>料液比例>海藻酸钠添加量>液压压强;利用Design-Expert 8.1.0软件对芝麻酱感官评分的多元方程进行模拟,结果显示该回归方程的方差显著性小于0.01(P<0.01),低脂芝麻酱响应面试验的实际值与回归方程的模拟值较接近;优化后的低脂芝麻酱最佳加工工艺为液压压强30 MPa、料液比例1∶1、黄原胶添加量0.03%和海藻酸钠添加量0.30%,该加工工艺条件下,低脂芝麻酱的感官评分为92分,此时芝麻酱酱香浓郁,浓稠度适中,黏稠度较高。

纳米茶籽油微囊对低脂猪肉糜制品品质影响

高脂产品低脂化符合消费者对健康的追求,是未来肉制品发展方向之一。本文以无茶籽油脂肪替代肉糜为对照组,考察了两种形式的茶籽油(Tea seed oil,TSO)及纳米微囊化茶籽油(Nano tea seed oil microcapsules,NTM)代替猪背膘对猪肉糜制品理化性质的影响,对不同脂肪替代肉糜制品保水性、蒸煮得率、水分分布、质构、微观结构、脂肪氧化水平等指标进行了研究。结果表明,添加50%、70%NTM可以改善添加TSO造成的肉糜制品保水能力的下降;NTM替代组的T_(21)弛豫时间、占比与无替代对照组组差异不显著(P>0.05),而TSO替代组不易流动水占比显著下降(P<0.05);NTM替代组,其L^(*)、b^(*)值较于无茶籽油替代组有所增强,a^(*)降低,且具有明显的脂肪氧化抑制效果,有效延长贮藏期;微观结构结果表明,NTM替代组油脂分布较TSO添加组更均匀,与蛋白质结合更紧密;质构特性结果表明,TSO替代会造成质构的劣化,而NTM可以改善劣化情况,其中添加70%NTM的肉糜弹性和粘度优于50%和70%NTM替代组。综上,添加70%NTM可以均匀分布于猪肉糜中,并与蛋白质之间形成更多的氢键,从而达到稳定低脂猪肉糜保水力,硬度,弹性等理化性质的目的。因此添加70%NTM的低脂肉糜品质最优。

青中年患者低盐低脂饮食干预与脑卒中发生发展的关联分析

目的研究青中年患者低盐低脂饮食干预与脑卒中发生发展的关联性。方法选取2021年7月至2023年2月住院的青中年脑卒中患者共计120例作为研究对象,遵循随机化原则分为观察组和对照组,每组60例。对照组运用常规营养支持医护模式;观察组运用低盐低脂饮食指导的医护理念。入院时和干预结束后3个月,评估2组患者的低盐低脂饮食指导指数。比较2组患者入院时、干预3周、干预结束时血红蛋白、血清白蛋白、总蛋白的变化。入院时、干预结束时、干预结束后3个月患者主观整体评估(PG-SGA)评分,并进行人体组成成分测定。结果低盐低脂饮食指导干预结束后3个月与入院时比较,2组自我保健、健康知识、生活方式、精神健康、生活技能及总分均有提高(P<0.05)。观察组与对照组相比,自我保健、生活方式、精神健康及总分提高的程度更明显(P<0.05)。2组从入院时干预3周、指导干预结束时血红蛋白、血清白蛋白、总蛋白呈明显下降趋势(P<0.05)。交互效应均有统计学意义(P<0.05),遂认为不同组间血红蛋白、血清白蛋白、总蛋白变化的趋势受到观察时间的影响。2组从入院时、干预3周、干预结束时PG-SGA得分呈明显下降趋势(P<0.05)。交互效应有统计学意义(P<0.05),遂认为不同组间PG-SGA得分变化的趋势受到观察时间的影响。2组从入院时干预3周、干预结束时体脂率、体重、BMI均呈明显下降趋势(P<0.05)。交互效应均有统计学意义(P<0.05),认为不同组间体脂率、体重、BMI变化的趋势受到观察时间的影响。结论对脑卒中采用低盐低脂饮食指导提高了患者的生活质量,具有良好、广阔的推广应用前景。

中低强度运动干预高脂饲养小鼠膝关节损伤软骨细胞LncRNA HOTAIR的表达

背景:中低强度有氧运动对膝关节软骨具有一定保护作用。长链非编码RNA对基因调节具有重要作用,其中,HOTAIR可以动员多个转录共同抑制因子,抑制某些基因表达。目的:检测HOTAIR及相关因子在高脂饲养小鼠及中低强度运动干预后膝关节软骨细胞中表达水平,探讨其在软骨损伤及运动康复中的作用。方法:C57BL/6雄性小鼠30只,随机分为对照组(正常饲养)、高脂静养组和高脂运动组,每组10只。高脂运动组进行8周中低强度跑台运动,对照组和高脂静养组笼中饲养,期间每周日称体质量。8周跑台结束后取材双下肢,采用Micro CT扫描膝关节,股骨髁成3D图像,获取相关参数;膝关节苏木精-伊红和番红固绿染色进行关节Mankin和OARSI评分;RT-PCR检测相关软骨代谢指标Ⅱ型胶原、基质金属蛋白酶13、白细胞介素1,脂代谢指标低密度脂蛋白受体相关蛋白5(LRP5),HOTAIR及其下游因子赖氨酸特异性去甲基化酶1(LSD1)mRNA表达。结果与结论:①高脂静养组和高脂运动组体质量均高于对照组(P<0.01),高脂运动组体质量低于高脂静养组(P<0.05);②高脂静养组和高脂运动组骨小梁连接密度均高于对照组(P<0.01);③高脂静养组Mankin和OARSI评分高于对照组(P<0.01)和高脂运动组(P<0.05);④对照组Ⅱ型胶原mRNA表达高于高脂运动组(P<0.05)和高脂静养组(P<0.01),高脂运动组Ⅱ型胶原mRNA表达高于高脂静养组(P<0.01);⑤高脂静养组基质金属蛋白酶13、白细胞介素1、低密度脂蛋白受体相关蛋白5、HOTAIR和赖氨酸特异性去甲基化酶1 mRNA表达高于对照组和高脂运动组(P<0.01);⑥结论:高脂饲养造成小鼠股骨髁骨质增加、膝关节软骨磨损,软骨细胞代谢紊乱,这一过程中HOTAIR的表达增加。8周中低强度跑台可减轻小鼠体质量、减缓膝关节软骨磨损、改善软骨细胞功能和下调HOTAIR表达。

低分子肝素与脂肪乳联合抗复发性流产作用及对促炎介质、免疫功能的调节作用

目的 探讨低分子肝素联合脂肪乳治疗复发性流产(RSA)的效果,分析其对妊娠结局、炎症介质、免疫功能的影响。方法 选取2021年2月至2022年3月驻马店市中医院收治的101例RSA患者为研究对象,随机分为单一组50例、联合组51例。两组接受常规基础治疗,在此基础上单一组接受脂肪乳治疗,联合组接受低分子肝素联合脂肪乳治疗,两组连续治疗至妊娠12周。对比两组临床疗效、妊娠结局、安全性。比较两组治疗前后T淋巴细胞亚群(CD4^(+)、CD8^(+)、CD4^(+)/CD8^(+))、炎症介质[白介素-10(IL-10)、白介素-17(IL-17)、巨噬细胞炎性蛋白1α(MIP-1α)]水平。结果 联合组总有效率、妊娠成功率高于单一组(P<0.05),两组不良反应发生率差异无统计学意义(P>0.05)。联合组妊娠12周CD4^(+)、CD4^(+)/CD8^(+)低于单一组,CD8^(+)高于单一组(P<0.05),血清IL-10、MIP-1α水平高于单一组,IL-17水平低于单一组(P<0.05)。结论 低分子肝素联合脂肪乳治疗RSA的效果确切且具有一定安全性,可改善妊娠结局,减少炎症介质生成,调节机体免疫功能。

长城三矿选煤厂从洗选矸石中回收低热值煤的工艺探索

长城三矿选煤厂洗选矸石中存在高密度低灰分的煤矸石,现有重介质分选工艺不能对其进行有效分选,直接废弃会造成煤炭资源浪费,直接燃烧产生的热量较少,并且会造成环境污染。通过对长城三矿选煤厂洗选块矸石进行试验分析,并调整末煤重介质旋流器锥角,对这部分低热值煤进行再回收利用,避免煤炭资源的浪费,提高了企业的经济效益。

Quality Characteristics of Gamma Irradiated Beefburger Formulated with Partial Replacement of Beef Fat with Olive Oil and Wheat Bran Fibers

Five beefburger formulations were prepared with substituting beef fat with olive oil and levels of wheat bran and irradiated at doses of 0 and 3 kGy, then samples were refrigerated stored and their quality characteristics were investigated. The results indicated that replacement of beef fat with olive oil and ascending levels of wheat bran in burger batter significantly decreased their contents of total lipids and saturated fatty acids, while increased their contents of dietary fibers, unsaturated fatty acids and the ratios of unsaturated and polyunsaturated fatty acids to the saturated ones. Moreover, significant improvements were observed in the cooking yield and moisture and fat retention of samples, proportionally to the added wheat bran, and both raw and cooked burger samples showed a high sensory acceptability. Irradiation of samples effectively inactivated Staphylococcus aureus, Salmonella and enterobacteriaceae and significantly reduced the counts of mesophilic and psychrophilic bacteria as well as molds and yeasts without any adverse effects on the quality characteristics of samples. Thus, reducing beef fat levels with the addition of olive oil and wheat bran produced a highly acceptable beefburger products with improved nutritional content as well as improved cooking and binding properties, while irradiation improved their microbiological quality.

Apoptosis induced by a low-carbohydrate and high-protein diet in rat livers

AIM: To determine whether high-protein, high-fat, and low-carbohydrate diets can cause lesions in rat livers.METHODS: We randomly divided 20 female Wistar rats into a control diet group and an experimental diet group. Animals in the control group received an AIN-93 M diet, and animals in the experimental group received an Atkins-based diet(59.46% protein, 31.77% fat, and 8.77% carbohydrate). After 8 wk, the rats were anesthetized and exsanguinated for transaminases analysis, and their livers were removed for flow cytometry, immunohistochemistry, and light microscopy studies. We expressed the data as mean ± standard deviation(sd) assuming unpaired and parametric data; we analyzed differences using the student's t-test. statistical significance was set at P < 0.05.RESULTS: We found that plasma alanine aminotransferase and aspartate aminotransferase levels were significantly higher in the experimental group than in the control group. According to flow cytometry, the percentages of nonviable cells were 11.67% ± 1.12% for early apoptosis, 12.07% ± 1.11% for late apoptosis, and 7.11% ± 0.44% for non-apoptotic death in the experimental diet group and 3.73% ± 0.50% for early apoptosis, 5.67% ± 0.72% for late apoptosis, and 3.82% ± 0.28% for non-apoptotic death in the control diet group. The mean percentage of early apoptosis was higher in the experimental diet group than in the control diet group. Immunohistochemistry for autophagy was negative in both groups. sinusoidal dilation around the central vein and small hepatocytes was only observed in the experimental diet group, and fibrosis was not identified by hematoxylin-eosin or Trichrome Masson staining in either group.CONCLUSION: Eight weeks of an experimental diet resulted in cellular and histopathological lesions in rat livers. Apoptosis was our principal finding; elevated plasma transaminases demonstrate hepatic lesions.

杏鲍菇玉米复合低脂香肠的配方研究

该研究以杏鲍菇浆和鸡胸肉糜为主要原料,加入大豆分离蛋白、玉米淀粉、玉米粒、白砂糖、卡拉胶、食盐、芝麻油、鸡精等辅料,经混合、灌制、蒸煮、冷却等工艺制作杏鲍菇玉米复合低脂香肠。在单因素试验的基础上,利用响应面试验对配方进行优化,以感官评分为指标,研究复合低脂香肠的最优配方。结果表明,最优配方为水与杏鲍菇的比例1∶1.2、玉米淀粉添加量15%、大豆分离蛋白添加量19%、卡拉胶添加量0.3%、鸡肉糜添加量35%,在此条件下制成的复合低脂香肠品质更佳,形态完整,口感良好。该研究结果为低脂香肠的生产应用提供了理论参考。

海藻膳食纤维对低脂低盐鸡肉法兰克福香肠品质的影响

以低脂低盐鸡肉法兰克福香肠为研究对象,探讨不同添加量(0.5%、0.75%、1%、1.25%、1.5%、1.75%)的海藻膳食纤维对其食用品质的改善效果。结果表明,随着海藻膳食纤维添加量的增加,低脂低盐鸡肉法兰克福香肠的蒸煮损失、L^(*)值和b^(*)值显著降低(P<0.05),而乳化稳定性、弹性、回复性、脆性和感官评价(致密性、多汁性、风味和总体可接受性)显著增大(P<0.05),且1.5%为最佳添加量(P<0.05)。扫描电镜结果表明海藻膳食纤维能够促进鸡肉蛋白凝胶形成致密的三维网状结构。因此,海藻膳食纤维能够提高低脂低盐肉糜体系的持水性和凝胶特性,进而改善产品的食用品质,为低脂低盐肉制品的开发提供技术指导。

热处理及成熟温度对低脂牦牛乳硬质干酪理化性质及品质影响

干酪减脂符合消费者健康需求,生产工艺是改善低脂干酪品质经济而简便的方式之一。该实验以未热处理、65℃30 min、75℃1 min、85℃15 s和4、12℃分别作为原料乳热处理和成熟温度条件,制作低脂牦牛乳硬质干酪,测定不同成熟时间(0、1、3、6个月)干酪的理化、品质指标。结果表明,随着原料乳热处理温度增加,干酪出品率、水分和总游离氨基酸含量增加,NaCl含量呈现降低趋势;3组热处理组干酪的硬度显著高于未热处理组,但随热处理温度增加,硬度下降;不同热处理组干酪之间弹性差异较小;85℃处理组干酪的黏聚性在成熟后期,显著低于其他3组干酪;整个成熟期内,85℃处理组感官品质评分均较高。相同热处理原料乳制作的干酪,12℃成熟时的硬度始终显著低于4℃成熟干酪,但是其NaCl和总游离氨基酸含量始终显著高于4℃成熟干酪;成熟时间少于6个月时,12℃成熟干酪的感官品质优于4℃成熟干酪。因此,原料乳热处理和成熟温度的提高能增加干酪中总游离氨基酸含量,降低其硬度和黏聚性,缩短干酪成熟时间,改善其品质。该研究为低脂牦牛乳硬质干酪的生产提供了理论指导。

植物乳杆菌胞外多糖协同鱼明胶改善低脂酸奶品质特性

以前期制备的Lactobacillus plantarum JLAU103胞外多糖(exopolysaccharide,EPS)为原料,将其按不同比例与鱼明胶(fish gelatin,FG)混合添加到低脂酸奶中,研究其对低脂酸奶品质特性的改善作用。结果表明:添加0.1%(m/m)EPS和0.6%(m/m)FG可提高低脂酸奶的持水力和pH值,降低滴定酸度,黏度趋于正常酸奶;使低脂酸奶的蛋白网状结构空隙变小,结构更加紧密。与低脂酸奶相比,0.6%FG+0.1%EPS组低脂酸奶的活菌数得到显著提升(P<0.05),达到8.40×10^(8)CFU/mL;特征挥发性风味物质如双乙酰、2-壬酮、2,3-戊二酮等含量明显增多,感官评分较高,且质构得到显著改善。流变学结果表明,添加EPS减小了低脂酸奶的触变环面积,增强了稳定性和总应变,使低脂酸奶形成更牢固的凝胶网络。因此,L.plantarum JLAU103 EPS与FG联合使用能够明显改善低脂酸奶的品质,具有很好的应用前景。