Buffalo Yogurt Fortified with Eucalyptus (Eucalyptus camaldulensis) and Myrrh (Commiphora Myrrha) Essential Oils: New Insights into the Functional Properties and Extended Shelf Life

Eucalyptus (Eucalyptus camaldulensis) and Myrrh (Commiphora Myrrha) essential oils (EOs) stand out for their benefits in terms of health and functionality. Buffalo set yogurt enriched with different concentrations of EOs (0.3, 0.6, and 0.9%) were investigated. The effects of addition on sensory, syneresis, antibacterial activity, and bioactive properties (total phenol content and antioxidant activity) of yogurt were studied. The most acceptable organoleptic properties of treated yogurt were those samples treated with Eucalyptus oil. The levels of syneresis were decreased by increasing the concentration of EOs. Moreover, the antioxidant activity, antibacterial activity, and total phenolic content were enhanced by increasing the concentration of EOs. Yogurt with 0.9% Eucalyptus oil showed the highest antioxidant activity and total phenolic content. The same concentration of Eucalyptus oil showed the highest antibacterial activity against S. typhimurium (the inhibition zone was 20.63 mm) then E. coli (the inhibition zone was 19.43 mm). On the other hand, the highest antibacterial effect against L. monocytogene was for Myrrh oil-enriched yogurt by 0.9% and the inhibition zone was 19.21 mm. The obtained results showed that Eucalyptus and Myrrh oils can be applied to yogurt to improve its beneficial properties in terms of physical characteristics and for human health due to their antioxidant activity and phenolic materials.     

利用高效液相色谱-串联质谱追踪酸奶发酵过程中的酪蛋白磷酸肽

酪蛋白磷酸肽(CPPs)是酪蛋白被磷酸化的片段,具有促进矿物元素吸收、抗氧化、预防龋齿等多种生物功能。该文利用高效液相色谱-串联质谱研究牛奶经嗜热链球菌(Streptococcus thermophilus)和保加利亚乳杆菌(Lactobacillus debrueckii subsp.bulgaricus)发酵后CPPs的释放规律。结果表明,在内源性蛋白酶的作用下牛奶含内源性CPPs,内源性CPPs主要来源于高丰度酪蛋白αs1-CN和β-CN。经乳酸菌发酵后,在乳酸菌蛋白酶的作用下更多酪蛋白的磷酸化位点暴露而产生大量CPPs,其中含SpSpSpEE特征结构的CPPs也在酸奶中检测到,CPPs的释放与酪蛋白结构密切相关。研究结果表明,牛奶经乳酸菌发酵后释放大量含特征结构SpSpSpEE的CPPs,可提高结合矿物元素的能力,从而增强其促进人体健康的生物功能。     

Microencapsulation of Bioactive Ingredients for Their Delivery into Fermented Milk Products: A Review

The popularity and consumption of fermented milk products are growing. On the other hand, consumers are interested in health-promoting and functional foods. Fermented milk products are an excellent matrix for the incorporation of bioactive ingredients, making them functional foods. To overcome the instability or low solubility of many bioactive ingredients under various environmental conditions, the encapsulation approach was developed. This review analyzes the fortification of three fermented milk products, i.e., yogurt, cheese, and kefir with bioactive ingredients. The encapsulation methods and techniques alongside the encapsulant materials for carotenoids, phenolic compounds, omega-3, probiotics, and other micronutrients are discussed. The effect of encapsulation on the properties of bioactive ingredients themselves and on textural and sensory properties of fermented milk products is also presented.     

The Effects of Adding a Gel-Alike Curcuma longa L. Suspension as Color Agent on Some Quality and Sensory Properties of Yogurt

Color is an important characteristic of food products. This characteristic is related to consumer acceptability. To use the entire rhizome of Curcuma longa (CL) as a food colorant, a novel gel alike stable suspension (CLS) was previously developed using cellulose nanofibers (CNFs). Therefore, the present study was conducted to evaluate the CLS as a color additive on a stirred yogurt. Three concentrations of CLS were studied (0.1, 0.125, and 0.15 wt. %) and compared to yogurt without CLS. The obtained yogurts were characterized through the determination of pH, titratable acidity, syneresis, color and curcumin content after 1, 7, 14, and 21 days of storage. Additionally, rheological and sensory measurements were performed on the samples after one day of storage. Results show that the addition of CLS does not affect the pH and titratable acidity of the samples, but all the yogurts showed an increase in their syneresis during the storage time, showing a breakdown of the gel structure. Furthermore, the CLS suspension has the ability to impart a yellow color to yogurts, a characteristic that was stable during storage. Finally, the addition of 1 wt. % or 1.25 wt. % of CLS allows the development of a yogurt with adequate sensory perception.     

热休克处理应用于直投式发酵剂对酸奶品质改善作用的研究

为研究热休克处理应用于直投式发酵剂对酸奶品质的改善作用, 通过保加利亚乳杆菌、嗜热链球菌和嗜酸乳杆菌制备直投式发酵剂, 比较3种菌的热休克处理实验组与未热休克处理对照组在冷冻干燥后的存活率及酸奶发酵性能. 结果显示: 热休克处理组发酵剂存活率极显著增加, 酸奶pH下降速度显著加快(P<0.01), 双乙酰、乙醛含量均显著升高(P<0.05), 蛋白质、活菌数含量均显著提升(P<0.01), 且使用经热休克处理制备发酵剂生产的酸奶在感官评价上优于未热休克处理组. 结果表明, 在冷冻干燥前进行热休克处理可以提高直投式发酵剂中乳酸菌的存活率、产酸产香等发酵性能, 改善酸奶的风味和品质, 为提升酸奶发酵剂的品质提供了一种新的方法.     

Film formation of yogurt under confined condition

The yogurt film confined within a nanogap was investigated by the thin film interferometry between two solid surfaces. Significantly thick film was found even under a low speed, which indicated yogurt might have excellent lubrication performance. The film thickness was much higher than the prediction of elastohydrodynamic lubrication theory. Experiment results indicated that the thick confined film of yogurt can be induced by the adhesion of organic material, which can sustain high pressure without being extruded under low speed. The effect of the rolling speed on film thickness shows that the lubrication under a high rolling speed tends to be the elastohydrodynamic lubrication. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of Oat β-Glucan on the Rheological Characteristics and Microstructure of Set-Type Yogurt

The oat β-glucan (OG) was added into set-type yogurt as a functional ingredient, in order to evaluate effects on the rheological characteristics and microstructure of set-type yogurt. When the OG concentration increased from 0 to 0.3%, the WHC gradually increased. At 0.3% OG, the set-type yogurt had the highest WHC of 94.67%. Additionally, the WHC continuously decreased, reaching the lowest WHC (about 80%) at 0.5% OG. When 0.3% OG was added, the highest score of sensory evaluation was about 85. The rheological result showed that the fermentation process went through the changes as follows: solid → liquid → solid → liquid. The addition of 0.3% OG decreased the fermentation time of set-type yogurt by about 16 min, making yogurt more inclined to be liquid. The acidity of set-type yogurt with OG was slightly higher. The result of microstructure showed that the addition of OG destroyed the three-dimensional network structure of yogurt, and some spherical aggregate particles could be clearly observed at 0.3% OG. Overall, this study provided a theoretical basis for the application of OG in set-type yogurt.     

Comparison of Dry,Wet, and Microwave Ashing Methods for the Determination of Al,Zn, and Fe in Yogurt Samples by Atomic Absorption Spectrometry

Abstract

Digestion methods such as dry and wet ashing and microwave oven were examined at various conditions to determine a rapid, reliable, and simple digestion procedure for yogurt. Digestion by microwave oven was found to be an excellent method in comparison with dry and wet ashing methods when only Al and Zn in yogurt samples were determined. Iron in this matrix is not completely digested by the microwave oven method at the examined conditions. From the obtained results, yogurt can also be a good source of essential nutrients such as minerals in human diet, especially zinc. Aluminum concentrations in yogurt samples fermented in Al containers were found to be significantly higher than in plastic containers. Al concentrations of yogurt taken from the bottom of the container were found to be higher than from the center and top of Al containers. The determinations of metals were carried out via an atomic absorption spectrophotometer using calibration curve and standard additions methods. Aluminum concentrations in yogurt samples produced in big production centers were found to be significantly higher than the other yogurt samples produced in‐house when plastic containers were used.     

Encapsulation of Vitamin E in Yogurt-Based Beverage Emulsions: Influence of Bulk Pasteurization and Chilled Storage on Physicochemical Stability and Starter Culture Viability

Yogurt is a nutritious food that is regularly consumed in many countries around the world and is widely appreciated for its organoleptic properties. Despite its contribution to human dietary requirements, yogurt in its traditional recipe is a poor source of fat-soluble vitamins. To respond to consumer demands and further increase the nutritional value of this product, this work aimed to fortify yogurt with vitamin E by using emulsification as the method of encapsulation. The effects of thermal processing and chilled storage on the physicochemical stability of the yogurt-based beverage was investigated. Vitamin E was only minorly affected by bulk pasteurization at 63 °C for 30 min and remained stable during storage at 4 °C for 28 days. Fortified samples showed increased in vitro antioxidant activity compared with non-fortified samples. Lactic acid bacterial counts were above the minimum recommended levels (>10⁶ cfu/g) after processing and storage. In conclusion, this work has demonstrated that emulsification can be an effective strategy for developing yogurt-based products fortified with fat soluble vitamins.     

Phyto-Enrichment of Yogurt to Control Hypercholesterolemia: A Functional Approach

Cholesterol is essential for normal human health, but elevations in its serum levels have led to the development of various complications, including hypercholesterolemia (HC). Cholesterol accumulation in blood circulation formsplaques on artery walls and worsens the individuals’ health. To overcome this complication, different pharmacological and non-pharmacological approaches are employed to reduce elevated blood cholesterol levels. Atorvastatin and rosuvastatin are the most commonly used drugs, but their prolonged use leads to several acute side effects. In recent decades, the potential benefit of ingesting yogurt on lipid profile has attracted the interest of researchers and medical professionals worldwide. This review aims to give an overview of the current knowledge about HC and the different therapeutic approaches. It also discusses the health benefits of yogurt consumption and highlights the overlooked phyto-enrichment option to enhance the yogurt’s quality. Finally, clinical studies using different phyto-enriched yogurts for HC management are also reviewed. Yogurt has a rich nutritional value, but its processing degrades the content of minerals, vitamins, and other vital constituents with beneficial health effects. The option of enriching yogurt with phytoconstituents has drawn a lot of attention. Different pre-clinical and clinical studies have provided new insights on their benefits on gut microbiota and human health. Thus, the yogurtphyto-enrichment with stanol and β-glucan have opened new paths in functional food industries and found healthy andeffective alternatives for HC all along with conventional treatment approaches.