不同菌株对酸奶品质与感官特性的影响

该研究以保加利亚乳杆菌（N14）和嗜热链球菌（L16）为基础发酵菌,分别添加干酪乳杆菌（GL2）、副干酪乳杆菌（GL6）、酵母 菌（Y18）、开菲尔乳杆菌（700）构成了五种酸奶发酵剂组合,分别测定这五组酸奶的酸度、质构及感官特征,采用高效液相色谱（HPLC）法对酸奶中的苹果酸、乙酸、柠檬酸、乳酸进行定量分析,评价添加不同菌株对酸奶口感和风味的影响。结果表明,4种菌株添 加均提高了酸奶的酸度,且酸奶酸度变化趋势与第一循环硬度、弹性、胶着性相同;添加菌株GL2、700和GL6提高了酸奶中乳酸的含 量;添加菌株GL2的酸奶感官评分最高（92.55分）,在果香、蒸煮味、纸板味方面表现突出,但添加菌株GL6的酸奶的感官特征与市售 酸奶最为接近。     

不同酸奶发酵剂的发酵性能比较

前期在单菌株筛选的基础上,获得7种保加利亚乳杆菌与嗜热链球菌组合的酸奶发酵剂。利用这7种发酵剂发酵制备酸奶,评价他们的产酸性能、后酸化能力,并分析所制备酸奶的物性学特性、乙醛和双乙酰产量,最后进行感官评价,以评价这些发酵剂的工业应用潜力。结果表明,7种酸奶发酵剂具有各自独特的发酵性能,可用于不同风味和质地酸奶的生产,具有工业开发潜力。     

Effects of exopolysaccharide-producing strains of thermophilic lactic acid bacteria on the texture of stirred yoghurt

Summary Rheological and sensory properties of yoghurts prepared from commercially available cultures that had ropy and non-ropy characteristics were compared. Our results from both instrumental and sensory data suggest that it may not be the amount of polysaccharide that is important to rheological properties, but the type of exopolysaccharide (EPS)-producing strains and consequently the interaction of the polymer with the milk proteins during the fermentation. Data also suggest that the interaction and co-operative growth that occurs in mixed cultures also influences the yield of EPS production in the fermentation, as combining two ropy strains does not lead to an increase in total polysaccharide, although the viscosity can be improved. Texture measurements for viscosity correlated with sensory evaluation of viscosity and with slipperiness.     

乳清浓缩蛋白对搅拌型酸奶品质特性影响的研究

研究了以全脂奶粉和乳清浓缩蛋白（WPC-3503）为原料，按照全脂奶粉：乳清浓缩蛋白为100：0，90：10，80：20，70：30的质量配比生产乳固形物含量为12％的酸奶，对含有不同乳清蛋白比例的酸奶在贮藏过程中理化特性、乳酸菌总数的变化以及感官特性进行了比较分析。结果表明，WPC-3503代替10％-20％全脂奶粉生产酸奶时，在贮藏过程中可减缓pH值及酸度的变化速度，提高酸奶的黏度和保水率，改善感官特性，但对乳酸菌总数无明显的影响。     

谷氨酰胺转胺酶对搅拌型酸奶品质的影响

因为谷氨酰胺转胺酶对乳蛋白有交联作用,所以在酸奶制作中加入谷氨酰胺转胺酶可以提高酸奶的品质,将0.2g/L牛乳的谷氨酰胺转胺酶使用不同的添加方法(对酶灭活和不灭活)应用到酸奶制作中,通过酸奶硬度、持水力、流变特性、乳酸菌等指标的变化及综合感官评价,评定谷氨酰胺转胺酶的最适添加方法。结果表明两种不同的酶添加方法都可以减弱酸奶后酸化,提高酸奶硬度、持水力和剪切应力。TGase酶与发酵剂同时加入显著提高了酸奶的理化特性(p<0.05),硬度在第21d达到最大,与对照组相比提高8.48g,持水力随贮存时间的延长,不断增大,增幅为5.41%。在贮存后期TGase酶活力减弱,对酸奶的质构无不良影响,而且这种方法不需要额外的酶反应时间,热处理工序及设备,符合实际生产的需求。      

Viability of Lactobacillus acidophilus in rice bran‐enriched stirred yoghurt and the physicochemical and sensory characteristics of product during refrigerated storage

This study was aimed at investigating the fortification of probiotic yoghurt with rice bran to increase nutritional properties of the product. The different levels of rice bran (0.3%, 0.6%, 0.9% and 1.2%) were incorporated into milk. The yoghurt samples were produced after pasteurisation, addition of starter culture and 1% Lactobacillus acidophilus suspension (6 × 10⁸ CFU mL^?1) and incubation. During sample storage in refrigerator, the viability of L. acidophilus, viscosity and physicochemical and sensory properties of product were investigated. Rice bran significantly increased the viability of L. acidophilus (P < 0.05). In addition, all probiotic yoghurts incorporating rice bran indicated higher viscosity and acidity and lower pH and syneresis compared to plain yoghurts. Furthermore, increments in rice bran incorporation levels resulted in a reduction in consumers' sample preferences. In general, the addition of rice bran at a suitable level could increase L. acidophilus viability and improve quality attributes of yoghurt.     

Effects of guar gum and arabic gum on the physicochemical,sensory and flow behaviour characteristics of frozen yoghurt

This study investigated the effect of guar gum and arabic gum on physicochemical, sensory and flow behaviour properties of frozen yoghurt. The results indicated that gums significantly affected the viscosity, overrun and melting rate of frozen yoghurt. The highest overrun value was observed in sample containing 0.5% arabic gum. Frozen yoghurt containing 0.3% guar gum had the highest viscosity. The longest first dripping time was observed in sample containing 0.5% arabic gum. Flow behaviour of samples showed that all frozen yoghurts exhibited shear thinning behaviour. Guar gum at a concentration of 0.2% and arabic gum at a concentration of 0.5% presented the best total acceptability. The results of this study revealed that the frozen yoghurt produced with arabic gum had the better overall sensory and physicochemical characteristics.     

Effect of microfluidization of heat-treated milk on rheology and sensory properties of reduced fat yoghurt

The effects of microfluidization at 150 MPa (MFz) and conventional homogenization at 20/5 MPa (CH) of heat-treated milk on the rheology and sensory properties of non- (0.1%) and low- (1.5%) fat stirred yoghurts were compared. Homogenization conditions clearly affected the sensory properties of reduced-fat yoghurts, but the effect was highly dependent on fat content. MFz of heat-treated milk yielded products with very different sensory profiles from the conventional yoghurts. For non-fat yoghurts, MFz of heat-treated milk enhanced the perception of buttermilk and soft cheese flavours, and natural yoghurt aroma and flavour, but also increased the intensity of undesirable mouthfeel characteristics such as chalkiness, mouth-dryness and astringency. For low-fat yoghurts, MFz significantly improved creaminess and desirable texture characteristics such as smoothness, cohesiveness, thickness, and oral and spoon viscosity. These differences in sensory profiles, especially textural properties, were partially related to rheological properties, particularly flow behaviour. MFz of heat-treated milk resulted in non- and low-fat yoghurts with higher yield stress, more pronounced hysteresis effect and higher viscosity than those of CH yoghurts of similar fat contents. These findings suggest that microfluidization may have applications for production of high-quality yoghurt with reduced-fat content.     

Influence of guar gum addition on physicochemical,microbial, rheological and sensory properties of stirred yoghurt

This study investigated the effects of adding guar gum (0, 0.6 and 0.8 g/100 mL) on the physicochemical, microbial, rheological and sensory properties of stirred yoghurt. Incorporation of guar gum into the yoghurt significantly affected the pH and colour, but did not significantly influence the lactic acid bacteria counts. The magnitudes of apparent viscosity (η_a,100), consistency index (K), yield stress (σ_oc), storage modulus (G′) and loss modulus (G″) for yoghurt samples containing guar gum (0.6–0.8 g/100 mL) were significantly greater than those for the control (without guar gum), indicating that guar gum can improve the steady and dynamic shear rheological properties of yoghurt.     

Effect of pullulan on the physicochemical properties of yoghurt

The effects of pullulan (PUL) addition (0, 1.0 and 2.0% w/ v) on the physicochemical properties of yoghurts stored at 4 °C for 28 days were investigated. Fortification of the yoghurt with 1% PUL had a weakening effect on the gel network structure, leading to a decrease in initial viscosity and an extreme increase in syneresis, when compared to control. The addition of 2% PUL largely improved product stability by increasing gel firmness and adhesiveness, showing higher viscosity and consistency index values as well as displaying the lowest syneresis. Storage time increased yoghurt gel firmness and susceptibility to serum separation.     

不同胞外多糖产生特性的乳酸菌菌种对酸乳品质的影响

不同EPS产生量的两种乳酸菌，用于酸乳的生产，在4种不同菌株组合形成的发酵乳中，球、杆菌比例和乳糖消耗基本一致，但是在粘度、EPS产生、EPS的单糖组成、对乳清析出的影响，以及感官等方面，均有区别。实验结果表明，在酸乳生产中，以产EPS的德氏乳杆菌保加利亚亚种不产EPS的唾液链球菌嗜热亚种组合较好。     

弱后酸化发酵剂对长保质期酸奶品质特性影响的研究

研究5种弱后酸化发酵剂在搅拌型酸奶中的应用。结果表明,科.汉森公司的YF-622菌种发酵的酸奶蛋白质水解能力最弱,后酸化程度最小,30℃贮存13 d后酸度仅为89°T,并且其黏度、持水力和感官特性也明显优于其他4种菌种发酵的酸奶,乳酸菌活菌数达到国家标准的最低限制(≥106 cfu/mL)。因此,可将其应用于长保质期酸奶的生产。     

基于正交实验和模糊评价的搅拌型桑果酸水牛乳配方优化

以桑果汁、水牛乳为原料,添加适量的白砂糖、柠檬酸和稳定剂,研究开发出营养丰富、风味良好的搅拌型桑果酸水牛乳。以滋味、香气、色泽和组织状态为评价因素,通过正交实验和模糊数学综合评价方法对搅拌型桑果酸水牛奶产品进行配方优化。结果表明:搅拌型桑果酸水牛乳的最佳配方为酸水牛乳80%,桑果汁量8%,白砂糖添加量8%,稳定剂添加量为0.25%,按该配方制得的搅拌型桑果酸水牛乳柔和细腻,乳酸发酵的酸奶味浓,具有桑果特有的香味,无异味,无气泡,无分层,色泽均匀。      

Effects of manufacturing process variables on the physicochemical and sensory characteristics of Galician chorizo sausage

Physicochemical and sensory changes were evaluated during the curing of Galician chorizo, comparing samples from three different manufacturers (each of whom uses different procedures for smoking and curing). The observed variations were in all cases largely explained by pairwise differences between one of the manufacturers (manufacturer C) and the other two and are probably attributable to the more traditional and less strictly controlled process conditions used by manufacturer C. © 2002 Society of Chemical Industry     

Influence of the stage of ripeness of plantains and some cooking bananas on the sensory and physicochemical characteristics of processed products

The influence of the stage of ripening of the fruit of cultivars of plantain (French Sombre) and some cooking bananas (Dwarf Kalapua and Bluggoe) on the sensory and physico‐chemical characteristics of processed products was evaluated. Chips made from these cultivars at corresponding stages of ripeness had water contents less than 20 g kg^?1 for fruits at stages 1 and 3 and less than 60 g kg^?1 for those at stages 4 and 5. There was no significant difference (p > 0.05) between the ash contents of chips at different stages of ripeness for all the cultivars. Protein contents increased with increasing ripeness for all the cultivars; the fat contents decreased with increasing ripeness and varied from one cultivar to another. The available food energy was more than 4840 kcal kg^?1 of chips for all the cultivars at all stages of ripeness. The best chips were obtained from fruits at stages 1 and 3. Flours obtained from the fruits of these cultivars at different stages of ripeness had water contents lower than 60 g kg^?1. The fat, ash and protein contents were low, while the carbohydrate contents were high. For all the cultivars the yields of chips and flour were higher for the plantain cultivar (French Sombre) than for the cooking banana cultivars, irrespective of the stage of ripeness of the fruits. Cakes made from the different flours had good nutritional quality. The cakes and chips submitted for sensory evaluation were all accepted by consumers, although to differing extents. Fruits at stages 1 and 3 of ripeness which presented fewer problems during drying were the most suitable for the manufacture of flour for making cakes. Copyright © 2004 Society of Chemical Industry     

亲水胶体对脱脂发酵乳储存稳定性和感官品质的影响

研究了明胶、琼脂和变性淀粉Textra对脱脂发酵乳的储存稳定性和感官品质的影响。通过采用Design-Expert7.0.0设计的响应面分析法对三者进行了优化,以确定其最佳水平。结果表明,当明胶用量1.80‰,琼脂用量1.92‰和变性淀粉Textra用量2.42‰组成的复合增稠稳定剂制得的脱脂发酵乳储存稳定性好(乳清析出率最低,表观黏度最高),且感官品质良好。