Microencapsulation of probiotic cells within emulsion is an efficient method to enhance the viability of probiotic bacteria. In the present study, free and encapsulated probiotic cells (Lactobacillus rhamnosus and Lactobacillus plantarum) in simple and multilayer emulsions were used to produce a set of probiotic yogurts. In all samples, an increasing trend in syneresis and acidity values and a decreasing trend in pH and viability of probiotic cells were observed during the storage time. However, the changes in these parameters were more significant for free-loaded probiotic samples. Moreover, the free cells showed poor survival in the yogurt samples by decreasing the viable cell count of probiotics from 7.71–7.59 logs CFU/mL to 6.93–6.82 log CFU/mL during storage, while encapsulation in the multilayer emulsion showed an insignificant reduction from 7.65–7.59 logs CFU/mL to 7.55–7.45 log CFU/mL at the end of storage. The obtained results showed that the type of probiotic bacteria had no significant effects on the physicochemical and structural properties of samples. However, encapsulating probiotics in multilayer emulsion led to a more homogenous structure in yogurt. The sensorial properties were also not affected by the probiotic type and the encapsulation method. Consequently, the multilayer emulsion can provide an ideal delivery carrier for encapsulating probiotic bacteria in dairy products.
Lactobacillus is a genus of gram-positive bacteria of high probiotic value. The bacteria of this genus are responsible for maintaining and promoting the microbial balance of the human gut, where they along with promoting better digestion and absorption, also help in suppressing many infectious diseases. Iranian traditional yogurt (Mast) is a rich source of Lactobacillus microorganisms and their identification can be explored for their use in industrial probiotics. This study is aimed at isolation and identification of different Lactobacillus strains present in the Mast. Forty samples of Mast from eight different regions of the Iran were cultured in De Man, Rogosa and Sharpe agar (MRS) media for isolation. The isolated strains were identified by morphological and biochemical methods using gram staining, catalase, oxidase, motility and indole tests. For biochemical identification, the isolates were subjected to carbohydrate fermentation test using phenol red broth base. Overall eight strains were majorly identified based on biochemical and morphological screening which were further confirmed using 16S rDNA-based identification. Two strain of Lactobacillus acidophilus, two strains of Lactobacillus bulgaricus, two strains of Lactobacillus delbrueckii and two strains of Lactobacillus casei were identified. Lactobacillus delbrueckii subsp. Bulgaricus isolated from Bushkan showed higher bile salt resistant activities (18.92, 13.56 and 10.22%) than that of the available Lactobacillus bulgaricus strain (3.08, 1.87 and 1.44%) in 0.3, 0.5 and 1.0% bile salt. This study thus provides insights into probiotic potential of Mast which could be explored in industrial yogurt and cheese production. HIGHLIGHTS Insight into Lactic Acid Bacteria profile of traditional yogurt of Iran. The Lactic Acid Bacteria profile varies from region to region. Proposes possible probiotics for commercial yogurt production from traditional yogurt of Iran.
Rice is one of the most highly consumed foodstuffs in the world. In keeping with this, produced rice of many regions of the world contains high lead content. The present research was done to study the effects of the pre-cooking process of rice with acetic acid and citric acid on the concentration of lead. Rice samples were divided into 5 different pre-cooking treatment groups of soaking in acetic acid 1% and soaking in citric acid 1% (2 hrs), boiling with acetic acid 1% and boiling with citric acid 1% (20 min) and finally 6 times rinsing with deionized water. Then, measurement of lead remains was done using an atomic absorption optical spectrometer equipped with a detector of graphite furnace with deuterium lamp. The mean concentration of lead in primary rice samples without any processing operation was 87±4.8 ppb. The mean concentration of lead in rice samples processed with soaking in acetic acid, soaking in citric acid, boiling with citric acid, boiling in acetic acid and finally 6 times rinsing with deionized water were 55±3.8, 14±1.6, 32±2.4, 14±1.1 and 30±0.5 ppb, respectively. The highest reeducation percent of lead in rice samples was obtained in both soaking with citric acid and boiling with citric acid (84%). In keeping with the high concentrations of lead in studied rice samples, obtained concentrations were lower than the allowed limit of lead announced with the international standard organization of Iran (150 ppb). Boiling and soaking of rice samples with citric acid 1% can be a convenient and fast way to reduce the concentration of lead in rice samples.
Fucoidan powder was added in amounts of 0.05, 0.1,0.3, and 0.5% to sour cream butter and sensory and chemical properties were tested on their shelf life for 60 days during storage. Peroxide levels initially increased until day 40 of storage and then decreased. Butter samples from the control group had the highest amount of peroxide on day 40 (15.25 ± 1.41 meq/kg butter), while samples treated with fucoidan 0.5% had the lowest amount of peroxide (6.35 ± 0.53 meq/kg butter). The acidity of butter treatments increased during storage (p < .05). Butter samples from the control group had the highest acidity at 60 days of storage (0.40 ± 0.033 mg KOH / g butter), while samples treated with 0.5% fucoidan had the lowest acidity (0.17 ± 0.013 mg KOH / g butter). The treated butter samples showed the highest stability. Fucoidan, as an antioxidant, reduces the taste, odor, and discoloration of butter added with fucoidan during storage because it completely removes odorless tasteless powder, and the free radical chain is involved in oxidation and improves product properties. The results showed that there are no significant changes in the acceptance rate of butter treated with fucoidan during 60 days of storage in the refrigerator (p > .05). The sensory scores of the treated butter showed that the sensory properties during the storage period were similar to the control samples, but on day 40 of storage, they decreased. In general, a concentration of 0.5% fucoidan delays the oxidative process and increases shelf life and is selected as a superior treatment in terms of sensory evaluation, and is introduced as a functional food.
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