RESUMO
Many dairy products are discarded and useless after end of shelf-life, which causes economic and environmental challenges. The objective of this study was to study the compositional characteristics of some dairy products before and after shelf-life, and develop a process to utilize those dairy products after end of shelf-life in non dairy applications (cosmetic cream and soap). Several dairy products, such as sterilized milk, yogurt, soft cheese, hard cheese, cream, and butter were collected from markets in Egypt before shelf-life and after three months of shelf-life. Electrophoresis analysis was conducted to estimate the changes in the protein fractions of protein products (sterilized milk, yogurt, and cheese) before and after expiration. Also, gas chromatography (GS) was performed to compare the fatty acids of fat products (cream and butter) before and after end of shelf-life. Sterilized milk, yogurt, soft, and hard cheese were turned into powder (Expired dairy products powder; EDPP) to be used as a raw material in manufacturing of cosmetic creams. The fat was separated from cream, butter, and hard cheese (Expired dairy products fat; EDPF) to be utilized in making soap. The formulated cosmetic creams were examined in vitro. Functional properties of cream were determined, such as appearance, spreadability, irritancy, and pH. Additionally, the soap quality was tested after manufacture. We found that dairy products, such as milk, yogurt, and cheese after shelf-life can be utilized as raw materials for the production of cosmetic creams, as well as production of soap from butter and cream. The produced products were similar to those in commercial markets. This study is an endeavor to conquer the dairy industry challenges, which are considered a huge loss from the economic and environmental aspects.
RESUMO
The objectives of this study were to produce probiotic yogurt (5.0-7.0 log cfu/g) fortified with nanopowdered eggshell (NPES) at a rate of 0.02, 0.04, and 0.06 mg/ml, as well as, examine the effect of NPES on the physicochemical, microbial, sensory properties, and shelf-life of probiotic yogurt. The NPES was prepared by milling preboiled dried eggshell using a mortar grinder. The size of the milled powder was measured to assure that the diameter of the powder is 27 ± 1.7 nm. Yogurt was manufactured by dividing the pasteurized milk into four aliquots portions. The first portion was utilized as control (T1), while the other three portions were supplemented with 0.02 (T2), 0.04 (T3), and 0.06 (T4) mg/ml NPES. All treatments were inoculated with 5.11 log cfu of Lactobacillus delbruckii ssp. bulgaricus (Lb) and Streptococcus thermophilus (St) combined and 5 log cfu of Bifidobacterium bifidum (Bb) per kg of milk at 40°C until the pH of 4.6 was reached. The acidity, sensory properties, Bb count, total bacterial count (TBC), yeast, and mold counts were examined. The results showed that the acidity was increasing during storage, however, increasing NPES resulted in low acid development (p < .05). The shelf-life of control was ended after 8 d of storage at 4°C because molds were grown on the surface of the sample. The TBC significantly decreased (p < .05) as the concentration of NPES increased. Bb count in probiotic yogurt was also decreasing during storage. Yeast and molds were detected in control after 8 d; however, NPES did not result in molds even after 16 d of storage but yeast was exhibited. The NPES improved the sensory evaluation of probiotic yogurt slightly and increased the shelf-life of probiotic yogurt as compared to control.
RESUMO
The objective of this work was to study the effect of different concentrations of inulin (0.2, 0.4, and 0.6%) on the viability of probiotic bacteria (Bifidobacterium bifidum) and sensory characteristics of probiotic yogurt. The yogurt was manufactured with Lactobacillus delbruckii ssp. bulgaricus (Lb), Streptococcus thermophilus (St), and Bifidobacterium bifidum (Bb). Raw milk was received, heated to 90°C, and divided into 4 aliquots portions. All portions were inoculated with 5.11 log cfu of Lb and St combined and 5 log cfu of Bb per kg of milk. The first portion was utilized as control (T1) while 0.2, 0.4, and 0.6% of inulin were added to the second (T2), third (T3), and fourth (T4) portions, respectively. All treatments were incubated at 40°C until a pH of 4.6 was reached. Subsequently, the yogurt was cooled and stored at 4°C for 16 days. Titratable acidity, total bacterial count (TBC), Bb count, yeast count, mold count, and sensory evaluation were determined during the storage. The results showed that the addition of inulin and the storage period have significant effects (p < .05) on the titratable acidity of the yogurt. The storage of control was ended after 8 days at 4°C due to the growth of molds on the surface of the samples. The TBC decreased (p < .05) over time in control from 8.28 to 7.97 log cfu/g. It was also decreased (p < .05) with increasing the concentration of inulin. However, the addition of inulin increased (p < .05) the viability of Bb during the storage, as well as, acted as an antimicrobial against molds in T2, T3, and T4. Additionally, there were no significant differences (p > .05) in the sensory evaluation of all treatments. We conclude that inulin can be utilized in the manufacturing of probiotic yogurt as a prebiotic, which, inturn, enhances the growth of Bb and increase the shelf-life.