Effect of Butternut Squash (Cucurbita moschata) Seed Powder on the Chemical and Rheological Properties of Stirred Cultured Camel Milk and Yoghurt

Research shows that producing fermented camel milk is hard because of the milk’s inability to form a firm coagulum, attributed to low levels of κ-casein and ꞵ-lactoglobulin and the large casein micelle size, leading to a weak network of casein formation. In an effort to address this issue, researchers turned to corn starch as a thickening agent, discovering that a concentration of 2.0% effectively improved the viscosity and significantly reduced syneresis in stirred camel milk yoghurt and cultured camel milk. This study explores alternatives to corn starch, focusing on butternut squash seeds as a promising substitute due to their hydrocolloid composition. By incorporating butternut squash (Cucurbita moschata) seed powder (BSSP) as a thickening agent, this study aimed at enhancing the chemical and rheological properties of stirred camel milk yoghurt and cultured camel milk. Fermented camel milk was prepared using 4 litres of camel milk, 2% starter cultures (thermophilic culture for yoghurt and mesophilic aromatic culture for stirred cultured camel milk) and BSSP 0.0% (negative control), 0.4%, 0.8%, 1.2%, 1.6%, 2.0% mixed with 0.4% gelatin. 2.0% corn starch mixed with 0.4% gelatin was used as a standard for comparison. Results showed that increasing the BSSP level significantly (p < 0.05) decreased the moisture content while increasing the total solid content of stirred fermented camel milk products. There was an increase in ash content with an increase in BSSP levels. There was a significant (p < 0.05) reduction in the pH, with an increase in BSSP levels in stirred fermented camel milk samples. Increasing the concentration of BSSP from 0.4% to 2.0% resulted in a significant (p < 0.05) increase in viscosity and a reduction in syneresis of stirred camel milk yoghurt and stirred cultured camel milk samples. This study demonstrated that BSSP effectively enhances the viscosity, reduces syneresis and increases acidity in stirred fermented camel milk products during storage.

大豆油体替代牛乳脂肪对牛乳稳定性及其酸乳品质的影响

本研究首先从大豆种籽中提取大豆油体,然后将大豆油体替代牛乳中的脂肪,探讨大豆油体替代牛乳脂肪乳在不同环境下的稳定性,最后将大豆油体替代牛乳脂肪乳进行酸乳加工,以无水奶油替代牛乳脂肪乳及牛乳进行对照,考察大豆油体替代牛乳脂肪乳对牛乳稳定性及酸乳品质的影响。结果表明,大豆油体替代牛乳脂肪乳、无水奶油替代牛乳脂肪乳及牛乳在pH 2.0和4.0时,粒径较大。在pH 2.0~10.0,大豆油体替代牛乳脂肪乳的粒径显著高于无水奶油替代牛乳脂肪乳及牛乳的粒径(P<0.05)。除200 mmol/L外,在NaCl浓度0~500 mmol/L条件下,大豆油体替代牛乳脂肪乳的平均粒径显著高于无水奶油替代牛乳脂肪乳及牛乳的粒径(P<0.05),但是3种乳液油滴均没有明显的聚集,表现较稳定。在不同热处理温度条件下,大豆油体替代牛乳脂肪乳、无水奶油替代牛乳脂肪乳及牛乳都具有较高的热稳定性。大豆油体替代牛乳脂肪乳经过6 h发酵后其pH值能达到酸乳的理想pH值4.5左右,而且用时较无水奶油替代牛乳脂肪乳及牛乳短。大豆油体替代牛奶脂肪乳发酵形成的酸乳黏度显著高于无水奶油替代牛乳脂肪乳及牛乳发酵的酸乳的黏度(P<0.05),而且酸乳的感官和质地均较好。本研究可为大豆油体替代牛乳脂肪进行乳制品加工提供参考。

不同氧化度的魔芋葡甘露聚糖对凝固型酸奶品质的影响

“健康低脂”的食品理念近来广受大众欢迎。为改善低脂凝固型酸奶的凝胶强度低等问题,向酸奶中添加氧化魔芋葡甘露聚糖(Oxidized konjac glucomannan,OKGM)作为脂肪替代物,通过对酸奶理化性质、质构、流变学特性和微观结构等指标的分析,探究不同氧化度OKGM对酸奶品质的影响。结果表明,含高氧化度的OKGM(OK-60、OK-90、OK-120)的酸奶与未添加OKGM的酸奶相比,硬度从375.90 g提高至436.67 g,持水力从28.03%提高至31.89%,同时,能够提高流变学特性中的表观黏度和粘弹性。扫描电镜和激光共聚焦结果显示,高氧化度的OKGM缩小了酸奶凝胶结构间的孔隙,提高了酪蛋白胶束间的聚集,使其平均粒径从88.27 nm增加到125.33 nm。然而,天然的魔芋葡甘露聚糖(Konjac glucomannan,KGM)和低氧化度的OKGM(OK-30)则会降低酸奶的质构、表观黏度和粘弹性,破坏酸奶的凝胶结构,导致其稳定性下降。感官评价结果显示,高氧化度的OKGM使酸奶更有光泽,体系更加均匀,且在滋味上更具优势,这也为健康低脂酸奶的开发奠定了理论基础。

玉木耳多糖发酵酸奶的研制及工艺优化

为开发高活性玉木耳多糖酸奶,以玉木耳多糖(Auricularia cornea var. Li polysaccharides,ACP)为原料,测定其基本组分与流变特性,并通过单因素实验及正交试验优化了ACP酸奶生产工艺,探究了ACP对酸奶品质的影响。结果表明:ACP总糖、糖醛酸、蛋白质含量分别为82.21%±2.40%,11.95%±1.28%,2.36%±0.10%。流变特性显示玉木耳多糖溶液既表现出液体的特征,也表现出固体的特征,具有良好的粘弹性,有作为增稠剂和凝胶剂的潜在应用价值。ACP能促进酸奶发酵,使乳酸菌活菌数增加,酸度上升,p H降低;ACP浓度范围为0.02%~0.08%可提高酸奶持水力,改善酸奶组织状态和稳定性,减少乳清析出;ACP添加量为0.04%时,酸奶持水力、硬度、稠度、粘聚性和粘度最大,感官品质最好,ACP添加量为0.06%时,酸奶乳酸菌活菌数最多,酸度最高。玉木耳多糖酸奶最佳生产工艺为添加鲜奶量的0.04%ACP、6%蔗糖、0.1%发酵剂,于42℃发酵7 h,于4℃冷藏24 h,制作的酸奶较普通酸奶具有更高的活菌数及更好感官品质和质构特性。本实验通过探索玉木耳多糖对乳酸菌发酵和酸奶品质的影响,以期为改善酸奶保健性能和品质,拓宽玉木耳多糖的应用范围提供科学理论依据。

微囊化植物乳植杆菌L3对酸乳贮藏环境的响应过程

利用低甲氧基果胶将自主分离的植物乳植杆菌L3(Lactiplantibacillus plantarum L3)包埋,制备水包油包水(W/O/W)型微胶囊,然后将L.plantarum L3微胶囊与市售发酵剂直投到鲜乳中,发酵制成酸乳,于4℃下模拟酸乳贮藏货架期,分别在0、7、14、21 d进行微胶囊模拟胃肠消化实验,采用乙二胺四乙酸二钠破碎,研究L.plantarum L3对酸乳发酵、贮藏及胃肠道环境的应激响应过程,包括活菌数测定、菌体形态观察、细胞膜脂肪酸组成分析和菌体胞内氨基酸组成分析等。结果表明:经21 d贮藏和模拟胃肠道处理后,微胶囊中的活菌数保持在9.74(lg(CFU/mL))左右,细胞结构清晰完整;不同贮藏期的微囊化L.plantarum L3中含量最多的氨基酸均为丙氨酸、谷氨酸和天冬氨酸;随着贮藏时间的延长,微胶囊包埋后的L.plantarum L3细胞膜不饱和脂肪酸与饱和脂肪酸的比值呈现先增加后降低的趋势,但均高于L.plantarum L3裸菌的比值。以上结果表明,W/O/W型微囊化包埋提高了L.plantarum L3在酸乳贮藏环境、胃酸、胆汁及肠液等不良环境下的存活率,为功能菌株在食品载体中的应用提供了科学依据。

桑葚魔芋酸奶的研制

以牛奶、桑葚汁、魔芋胶和白砂糖等为原料,研制出一款风味营养兼具的桑葚魔芋酸奶。以感官评分作为评价指标,通过单因素试验和正交试验进行桑葚魔芋酸奶的配方优化。结果表明,最佳配方为每份桑葚魔芋酸奶中白砂糖添加量6.0%,魔芋胶添加量0.2%,发酵剂添加量4.0%,桑葚汁添加量12.0%。经此工艺制作而成的酸奶色泽均匀、呈浅粉色,组织细腻、无裂纹、无乳清析出,口感酸甜适中,有浓郁的发酵风味和桑果香味。品质评价结果显示,桑葚魔芋酸奶的持水力为83%,总酸度为97.0°T,可溶性固形物含量为14.0%,均符合国家标准,是一款兼具风味和营养的功能性酸奶产品。

Study on Honey Stirred Yoghurt

[Objective] In this study, the aim was to study the optimal formula and technique of honey stirred yoghurt. [Method] The optimum formula and production technique of the honey stirred yoghurt were confirmed by studying the effects of the additive amount of honey, the adding time of honey, thermal death point, the ho- mogenization pressure and stability test on the sensory quality of stirred yoghurt. [Result] The experiment showed that the fermentation temperature of the honey stirred yoghurt should not be too high, and it should be close to that of common yoghurt. In addition, the fermentation time should not be too long, because along with the extension of fermentation time, there would be abnormal smell in the yo- gurt. The optimum formula and production technique were as follows： the additive amount of honey, sugarcane and fermentation agent was respectively 3%; two-sec- tion homogeneous pressures of the fresh milk were I ： 70 MPa, I1：30 MPa; the thermal death point was 85 ℃ and the time was 10 min; the fermentation occurred at 42℃, and the fermentation of the products was stopped when the ultimate acidity was among 0.70%-0.75%. [Conclusion] The study could provide some refer- ences for the production and processing of honey stirred yoghurt.

乳酸菌发酵酸乳理化性质及微生物代谢研究进展

乳酸菌是一类能够将糖类发酵为乳酸的微生物,其广泛应用于酸乳制品的生产。不同的乳酸菌在发酵过程中表现出不同的特性,这些独特的特性不仅改变了酸乳的理化性质,同时还对其营养价值产生了重要影响。本文综述酸乳制品与微生物代谢之间的关系,特别关注微生物在酸乳制作过程中的作用和影响。酸乳的制作依赖于特定微生物(如乳酸菌)的发酵作用,这些微生物不仅能转化乳糖生成乳酸,从而改变酸乳的pH值和质感,还能合成一系列生物活性物质,如维生素,这对消费者的健康具有积极影响。通过分析近些年国内外学者对于酸乳发酵机制的研究,揭示微生物多样性对产品特性的贡献。此外,探讨酸乳中微生物代谢产物的健康益处,包括改善肠道健康、增强免疫力等,为酸乳制品的研发与创新提供科学依据和技术指导。

响应面法优化苦瓜红枣酸奶的工艺研究

研究了苦瓜汁添加量、红枣汁添加量、木糖醇添加量对苦瓜红枣酸奶品质的影响。以感官评分为评价指标,通过中心组合试验设计,响应面优化分析得到苦瓜红枣酸奶的最佳工艺配方为红枣汁添加量24.74%,苦瓜汁添加量15.14%,木糖醇添加量8.08%。

小麦低聚肽制备凝固型酸奶及其发酵特性的研究

选取3种酶(胃蛋白酶、碱性蛋白酶和风味蛋白酶)对谷朊粉进行水解,将不同酶解时间得到的小麦低聚肽加入酸奶中,代替部分牛奶蛋白(3%),以酸奶的pH值、滴定酸度为指标进行感官评价及质构分析,筛选出促酸奶发酵能力较好的酶解物,然后将小麦低聚肽按分子质量进行超滤膜分离,并评价和比较不同肽段的促酸奶发酵能力。结果表明,用碱性蛋白酶水解小麦面筋蛋白24 h的小麦低聚肽促酸奶发酵能力最佳,其中分子质量为1.5~3.5 kU的肽段极大地缩短酸奶的发酵周期,改善了酸奶的感官结构特性。

Probiotics Bacteria from Egyptian Infants cause Cholesterol Removal in Media and Survive in Yoghurt

One of the most significant groups of probiotic organisms are the lactic acid bacteria, commonly used in fermented dairy products. In this study, cultures were isolated from two infants. After screening for the classic properties of probiotic organisms, four promising isolates were identified as two strains of Lactobacillus acidophilus (P106, P110), strain of Lactobacillus plantarum (P164) and Lactobacillus. pentosus (P191)which were tested for capability to remove cholesterol and to deconjugate sodium taurocholate from the culture medium. Results showed that a considerable variation existed among cultures in their growth viability in the presence of bile salt, deconjugation of sodium tauro-cholate and assimilation of cholesterol from the medium. All tested strains removed less cholesterol from the broth (ranged from 4.02-24.32%) compared to those grown in broth supplemented with 0.2% bile salts (from 29.02 to 45.3). Lactobacillus acidophilus P106 appeared to be more active in bile salt hydrolase compared to the other strains, and therefore, is regarded as a suitable candidate probiotic and adjunct culture.These strains were employed to make yo-ghurt and, in order to achieve a short production time;a two-stage fermentation procedure was used with Streptococ-cus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus providing the rapid acidification. Storage trials at 4o C showed that the viability of the probiotic cultures was retained over 15 days.

Biofunctionality of Probiotic Soy Yoghurt

Soybean provides health benefits such as reducing cardiovascular disease, reducing menopausal symptoms, weight loss, arthritis, diabetes, osteoporosis and brain function. It contains phytochemicals such as isoflavones, saponins, phytosterols that promote health benefits. Soy food products are perceived as healthy food and are considered an important part of the diet. More than 50% consumers in the USA agreed that soy foods are healthy foods. Soymilk is considered as a suitable economical substitute for cow’s milk and an ideal nutritional supplement for lactose-intolerant population and also considered cholesterol free product for cardiovascular disorders. Fermented soy milk is a good source of bioactive peptides such as anti-ACE, antioxidative, anti-cancer and immunomodulatory. Many fermented soy milk based products such as soy cheese, soymilk-kefir, soy yoghurt etc. are produced.

Chemical, Nutritional, Rheological, and Organoleptical Characterizations of Stirred Pumpkin-Yoghurt

Pumpkin contains considerable amounts of bioactive compounds which hardly valorized in dairy products. This study aims to investigate the chemical, nutritional, rheological, and organoleptical properties of prepared stirred pumpkin-yoghurt. Stirred yoghurt with three different pumpkin varieties pulp [American (AP), Domestic (DP), and Indian (IP) pumpkin] at 15% was prepared and stored at 5°C ± 1°C up to 14 d. The chemical properties of yoghurts include protein, fat, crude fiber, and available carbohydrates were significantly affected by adding pumpkin without remarkable change in caloric value. Addition of pumpkin pulps decreased the pH and increased the acidity of stirred pumpkin-yoghurt significantly (P -1 in all stirred yoghurts after 1 d. After that, it was increased without notable effect of adding pumpkin pulps, and with slight simulation in LAB, growth was noticed in DP and IP yoghurts. Total phenolic compounds (TPC), total flavonoid (TF), total flavonols (TFL), carotenoids contents, and antioxidant capacity of pumpkin-yoghurts were significantly increased. Fortifying yoghurt with pumpkin pulp was associated with a statistically significant effect on sensory parameters such as flavor, color, and overall acceptability. Scores of AP yoghurt showed the highest score which significantly differed from CY. It is obviously showed that panelists were favored the prepared stirred pumpkin-yoghurt. Thus, it is recommended that adding pumpkin pulps increases yoghurt health benefits and could be scaled up further.

Antioxidant, Some Flavor Components, Microbiological and Microstructure Characteristics of Corn Milk Yoghurt

Corn milk is considered as a new innovation especially in the making of yoghurt based products. The present study was conducted to study antioxidants components such as (phenols compounds and DPPH scavenging activity), total volatile free fatty acids, microbiological and microstructure characteristics in yoghurt samples produced from two different ratios of buffalos and corn milk (70:30 coded A and 60:40 coded B) respectively. Results indicated that the increasing ratio of corn milk led to increase the content of phenolic components and DPPH scavenging activity. Total viable content decreased in samples (70:30 and 60:40). Streptococci and lactobacilli count decreased by the increase of corn milk in produced samples. Results also show that the trend of yeasts content was the opposite ones. Election microscopy examination revealed that adding corn milk to yoghurt had more smoothly and systematically distributed casein with a bit coarse structure less porosity in the network of casein. From these results could be concluded that adding 40% corn milk during processing of yoghurt is increasing the antioxidant activity and improves the microstructure as well.

Optimization of a Tiger Nut-Based Yoghurt Formulation by Response Surface Methodology

Tiger nut is a comestible tuber which offers many under products such as yoghurt. The parameters influencing the quality of yoghurt being numerous, response surface methodology was used to optimize the formulation in order to reach a low intake of milk powder. The volume of tiger nut milk, mass milk powder and sugar mass are the factors monitored while the titratable acidity (AT), pH, dry soluble extract (ESS), ash, viscosity and color are the expected responses in these tests. The data are processed with a degree of confidence p < 0.05 associated with statistical analysis by the software Statgraphic Centurion XVI version 16.2.04. The different tests show that the factors have overall significant effects (p < 0.05) on the acidity, the ashes and the Whiteness index. The linear and quadratic factors of tiger nuts milk as well as those linears of the milk powder have significant effects (p < 0.05) on the pH and the ashes. The linear factors of milk powder have significant effects on DSE, AT and pH. The optimal formulation yielded a volume of tiger nut milk equal to 3.7 L/kg, a mass of powder milk of 63.4 g and 75 g of sugar for one kilogram of yogurt. With a desirability of 75%, this model is apt to explain the results and the experimental values fit with the predicted ones and are within the norms. The proximate analysis of optimal yoghurt formulation shows that fat and proteins contents are respectively 5.67% and 2.2%. Calcium, magnesium and potassium contents are respectively 160, 40 and 180 mg in 100 g of yoghurt.

Physicochemical and Organoleptic Characteristics of Manufactured Buffalo Milk Yoghurt Incorporated Soy and Corn Milks

Soy-corn-yoghurt is a fermented product that obtained from inoculation of yoghurt starter to soy corn milk. The present study was conducted to study the use of different ratios of soy corn milk and corn milk only with buffalo milk in the manufacture of yoghurt. Two experiments were carried out , the first experiment was 100 ml buffalo milk :soy corn milk ratios 90:10, 80:20, 70:30, 60:40 and 50:50 (w/w), the second was buffalo milk with Corn milk 90:10, 80:20, 70:30, 60:40, 50:50 and 40:60 respectively and 100% buffalo milk as control. Treatments were coded B1, C1, D1, E1 and F1 in the first experiment, while B2, C2, D2, E2, F2 and G2 for the second respectively. All treatments subjected to chemical and organoleptic assessment. It was found those pH, total protein, fat content were decreased with increasing the ratio of soy corn milk in the product. Also, increasing the ratio of corn milk led to decrease all the previously mentioned characteristics. Curd firmness values for yoghurt made from (70:30) coded D2 and (60:40) coded E1 were higher than that of other treatments. Results indicated that mixes of (50:50) coded F1, (60:40) coded E1 and mixes (90:10) coded B2, (80:20) coded C2 and (70:30) coded D2 had the highest sensory scores and chemical quality.

Characteristics of physico-chemical properties, volatile compounds and free fatty acid profiles of commercial set-type Turkish yoghurts

Ten most popular brands of commercial Turkish set-type yoghurts were collected from local retail outlets in Hatay, Turkey for two separate periods, and analyzed for basic nutrients, physico-chemical properties, volatile aroma compounds and free fatty acid profiles to compare their differences among the yoghurt products. The results showed that there were significant differences (P<0.05, 0.01, or 0.001) and variations in physico-chemical indices, volatile aroma compounds and volatile free fatty acid profiles among the yoghurt brands, which ultimately influence the flavor quality of the product. Acetaldehyde was predominant volatile compound in yoghurts, which followed by acetone, acetoin, diacetyl and ethanol. The level of diacetly was inversely related to titratable acidity, acetaldehyde and ethanoic acid. From ketones with high carbones 2-undecanone and 2-pentadecanone were higher than 2-butanone, 2-nanonane and 2-tridecanone. These ketones are related to fat content of yoghurt. Among short chain free fatty acids, ethanoic (acetic) acid was the most abundant in yoghurts, followed by hexanoic, octanoic and butanoic acids. These differences in detected chemical compositions of volatile compounds and free fatty acids would be applicable to predict flavor, nutritional value, quality control or shelf-life of the commmercial set-type Turkish yoghurts.

Evaluation of sensory properties and their correlation coefficients with physico-chemical indices in Turkish set-type yoghurts

Sensory properties and physico-chemical parameters of 10 most popular brands of commercial set-type Turkish yoghurts were evaluated and correlation coefficients between the two indices were investigated. The results indicated that increases in volatile compounds (acetaldehyde, 2-butanone, 2-nanonane, ethyl acetate), titratable acidity, ash and fat contents inversely correlated with the overall acceptability score of the yoghurt. However, diacetyl, C4 to C12 free fatty acids, pH, whiteness index and texture positively correlated with overall acceptability of the yoghurt products. It was concluded that the acceptability of the Turkish set-type yoghurts is mainly governed by the fifteen volatile compounds as well as the physico-chemical properties determined. Thus, the overall acceptability of the yoghurts was not influenced by a single characteristic, but rather by complex in nature.

Effect of Okra Pectin on the Sensory, Physicochemical and Microbial Quality of Yoghurt

The objective of this work was to investigate the effect of okra pectin from two genotypes (asha and agbagoma) on the physicochemical, sensory and microbial quality of yoghurt. Okra pectin concentrations (w/w pectin to milk powder ratios) of 0.2%, 0.4% and 0.6% were used in the yoghurt preparation and its water holding capacity, titratable acidity and pH were analyzed against a control (0.0% pectin) weekly for a month. Consumer acceptability tests for the yoghurt samples were carried out using 50 untrained panellists on a 7-point hedonic scale. Total aerobic microorganisms present in the most preferred samples were enumerated over a four-week period. Results indicated that samples containing 0.2% asha pectin were most preferred by panelists. Water holding capacity varied significantly with those containing asha pectin higher than agbagoma counterparts and the control. There was a decline in pH with increasing pectin concentration and over the storage period. Samples containing agbagoma pectin had lower pH (3.60 - 4.32) compared to samples containing asha pectin (4.22 - 4.45). Titratable acidity increased during the storage period and with increasing pectin concentration. After four weeks of storage at 4°C sample containing 0.2% agbagoma pectin had the least microbial count (7.6 × 105 ± 4.51 cfu/g), followed by the sample containing 0.2% asha pectin (2.4 × 107 ± 11.14 cfu/g) and the control (8.6 × 107 ± 5.57 cfu/g). The study revealed that addition of okra pectin at 0.2% improved the consumer acceptability of yoghurt and 0.2% agbagoma pectin inhibits the proliferation of aerobic microbes. Addition of okra pectin also improved the water holding capacity and reduced whey exudation.

Isolation of Red Rose Anthocyanin Pigment and Its Application to Inhibit Lipid Oxidation in Yoghurt

Anthocyanin is a water soluble natural pigmen, which could be extracted from Red Rose. Color is an important factor to determine the quality of foods, so that the pigments isolation must be selected type of solvent for extraction process. Besides functioning as dyes, anthocyanins have a role as a good antioxidant, so it can be used to protect the fat content of fermented milk such as yoghurt. This experiment was to find out the effect of different solvent type on extraction pigment （aquadest： sitrat acid/lactic acid/sulfate acid/chloride acid） and to determine the effect of the addition of anthocyanins in protecting the fat content of yogurt on several levels addition. The research result showed that anthocyanin＇s pigment of red rose from petal flower＇s could be effective solvent extracted using lactic acid 0.02 M and increased fat stability of yoghurt. The anthocyanin pigment showed with HPLC analysis that pigment resulted TLC analysis at rite time 13.10 （as Cyanidin glucoside） and 22.61 （as Malvidin glucoside）. Yoghurt that given anthocyanin pigment has proven that fat content can be maintained its 86.7% （fat content with 2% pigment as such as 0.117% and without pigment 0.087%） after being stored for 6 days at cold and room temperature.