Background and Objectives: Propionibacterium is capable of producing important industrial products such as propionic acid, vitamin B12 and bacteriocin. They have also probiotic benefits and growth factors for the intestinal useful bacteria. The goal of this research was evaluation of the influence of process variables on vitamin B12 production in fed-batch fermentation of a dairy beverage containing propionic acid by Propionibacterium freudenreichii ssp. shermanii.Materials and Methods: Fermentation was conducted in a 3-L fermentor containing base medium and molasses as the carbon source to which the feeding was added after 36 hours. Sampling was done for biomass and vitamin measurements in 24 h intervals. The content of dry biomass and vitamin B12 was measured by freeze drying method and HPLC, respectively.Results: Statistical analysis of the results showed that all process variables had significant effect on the response of the system (P<0.05). The final concentration of vitamin B12 (30 mg/L) and productivity (7.5 mg/L.h) was obtained from Treatment 9 while the condition of this treatment was the best. In this research, inocula and their volume as well as feeding had no significant impact on the productivity of vitamin B12 fermentation (P>0.05). Type of nitrogen source and feeding strategy were the most significant factors in this research, so using corn steep liquor and lactose significantly increased vitamin B12 production.Conclusion: The best conditions for vitamin B12 production include: 30oC, pH=6.5, 25 g/L molasses, 10 g/L corn steep liquor instead of yeast extract, 96 h fermentation, using Propionibacterium freudenreichii with 5% v/v, and continuous feeding of lactose by 0.04 L/h rate. The results showed that the highest level of vitamin B12 was at concentration of 30 mg/L, production yield of 14.48 mg/g, and productivity of 7.5 mg/L.day.

Doogh is a fermented dairy product that derived from a combination of water and yoghurt and some flavoring additives. In this study, the effect of adding of whey powder in range of 0.2 to 0.4%, commercial stabilizer in range of 0.2 to 0.4% and milk powder in range of 0.3 to 0.5%, on phase separation of dooghby response surface methodology and also the rheological andorganoleptic properties by 5-point hedonic method were investigated. The results showed that with increasing stabilizer phase separation decreasedas well as increased whey powder to 0.3% (P<0.05).The results of optimization showed that the phase separation of dooghwas 57% by using of 0.4% commercial stabilizer, 0.35% whey powder and 0.4% milk powder. Also, increasing of these compounds changeddoogh rheologicalbehavior from newtonian to shear thinning. The optimized formulation gained the highest score of sensory evaluation.

The objective of this research was to produce fermented dairy beverage with Propionibacterium freudenreichii ssp. shermanii and study the microbiological characteristics immediately after fermentation and during cold storage. In this study, impact of two process variables of incubation temperature and inoculation ratio on microbiological characteristics was studied by full factorial design. For the preparation of the fermented dairy beverage, a mixed culture of Lactobacillus acidophilus and Propionibacterium freudenreichii ssp. shermanii was grown at the ratio of 1: 2, 1: 4 and 1: 8 and incubation was performed at 30, 35 and 40 oC until the pH reached 4±0.1. Cell count of L. acidophilus was conducted on MRS Agar and incubation at 37 oC. Enumeration of P. freudenreichii ssp. shermanii was done on sodium lactate agar (NaLa agar) medium and incubation at 30 oC. In the most suitable condition for propionic acid production, profile of viability of microorganisms was determined in intervals of 0, 7, 14, 21 and 28 days. Also, phase separation of produced beverage was studied during the first week of storage at 4 oC. The maximum viable cell count of P. freudenreichii ssp. shermanii was occurred by inoculation ratio of 1 to 4 and incubation temperature of 30 oC. There was an adverse and significant (P<0.05) relationship between viability of P. freudenreichii ssp. shermanii and incubation temperature. The maximum cell count of L. acidophilus was observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at ratio of 1 to 8 and incubation temperature of 35 oC. Considerable decreased cell counts of P. freudenreichii ssp. shermanii and L. acidophilus were obtained during the first and the last weeks of cold storage, respectively.

Background and Objective: Increasing trends of overweight and obesity prevalence have prompted food producers to develop products that can enhance satiety signals. The role of short-chain fatty acids as satiety-inducing triggers seems to be of interest in this regard. The objective of this research was to investigate the impact of two process variables, namely, incubation temperature and inoculation ratio of starter bacteria, on propionic acid production in the fermented dairy beverages containing Propionibacteriumimmediately after fermentation and during cold storage.Materials and Methods: Fermented dairy beverage (FDB) samples were prepared using mixed cultures ofLactobacillus acidophilus and Propionibacterium freudenreichii ssp. shermanii at a ratio of 1: 2, 1: 4 and 1: 8, repectively, at incubation temperatures of 30, 35 and 40°C, until the pH reached 4.0 ± 0.1. Propionic, lactic and acetic acid contents of the samples were measured immediately after fermentation using HPLC.The FBD samples were refrigerated for 28 days and the concentrations of the acids in the samples with the highest propionic acid content were measured. Sensory evaluation of the samples produced was made by 11 trained panelists using the hedonic scale.Results: The maximum propionic acid content (w/w%) was observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at a ratio of 1: 4 and an incubation temperature of 30 °C. It increased from 0.75 at day 0 to 1.2 at day 28 during storage at 4 °C.Conclusion: The incubation temperature had a statistically significant inverse effect (P<0.05) on the propionic acid production in the fermented dairy beverages.

The objective of this research was to produce fermented dairy beverage with Propionibacterium freudenreichii ssp. shermanii and study the microbiological characteristics immediately after fermentation and during cold storage. In this study, impact of two process variables of incubation temperature and inoculation ratio on microbiological characteristics was studied by full factorial design. For the preparation of the fermented dairy beverage, a mixed culture of Lactobacillus acidophilusand Propionibacterium freudenreichii ssp. shermanii was grown at the ratio of 1: 2, 1: 4 and 1: 8 and incubation was performed at 30, 35 and 40 oC until the pH reached 4±0.1. Cell count of L. acidophilus was conducted on MRS Agar and incubation at 37 oC. Enumeration of P. freudenreichii ssp. shermanii was done on sodium lactate agar (NaLa agar) medium and incubation at 30 oC. In the most suitable condition for propionic acid production, profile of viability of microorganisms was determined in intervals of 0, 7, 14, 21 and 28 days. Also, phase separation of produced beverage was studied during the first week of storage at 4 oC. The maximum viable cell count of P. freudenreichii ssp. shermanii was occurred by inoculation ratio of 1 to 4 and incubation temperature of 30 oC. There was an adverse and significant (P<0.05) relationship between viability of P. freudenreichii ssp. shermanii and incubation temperature. The maximum cell count of L.acidophiluswas observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at ratio of 1 to 8 and incubation temperature of 35 oC. Considerable decreased cell counts of P. freudenreichii ssp. shermanii and L. acidophilus were obtained during the first and the last weeks of cold storage, respectively.

Background and Objectives: Traditional fermented cereal beverages such as Obushera from sorghum and/or millet are commercialized owing to their popularity among consumers. However, Obushera separates into two phases after processing, which could be mistaken for spoilage. Additionally, Obushera has a limited shelf life of 4– 7 days at room temperature. The objective of this study was to assess the potential of various stabilizers and preservatives for the production of acceptable shelf-stable Obushera. Materials and Methods: Effects of seven treatments of 1) 0. 4% xanthan gum, 2) 0. 4% carboxymethyl cellulose, 3) Lactobacillus rhamnosus yoba, 4) 0. 4% xanthan gum and Lactobacillus rhamnosus yoba, 5) 0. 4% carboxymethyl cellulose and Lactobacillus rhamnosus yoba, 6) 0. 4% xanthan gum and 0. 4% carboxymethyl cellulose and Lactobacillus rhamnosus yoba, and 7) a control (no stabilizers) on sedimentation rate were assessed within 120 h at room temperature. Effects of four treatments of 1) pasteurization (90  C for 10 min) and 0. 25% xanthan gum, 2) pasteurization and 0. 25% xanthan gum and 0. 2% potassium sorbate and 3) pasteurization and 0. 25% xanthan gum and 0. 1% sodium-benzoate and 4) control (pasteurized with no additives) on shelf stability and consumer acceptability were investigated. Results: Treatments with xanthan (sedimentation index of 0– 25%) for stabilizing Obushera were significantly (p < 0. 05) more effective than those with no xanthan (sedimentation index of 49– 67%). Xanthan (0. 25%) significantly (p < 0. 05) improved consumer acceptability of Obushera. All preservation treatments (p > 0. 05) prolonged the shelf life of the beverage up to four months. No microbial growth was detected in the products during storage while pH (3. 7– 4. 0) and acidity (0. 5– 0. 6%) did not change significantly (p > 0. 05). All products were acceptable during storage. Conclusions: Obushera and related products can be stabilized and preserved using xanthan (0. 25%) and pasteurization (90  C for 10 min) with no added preservatives.

Production of fermented functional foods containing micronutrients is required for their health beneficial properties. Impact of 11 process variables on vitamin B12 production in a dairy beverage containing propionic acid was investigated. Propionibacterium freudenreichii ssp. shermanii was applied in a 3-l fermentor in fed-batch fermentation system. The most suitable conditions for vitamin B12 production were achieved by 5% v/v inoculum size containing Propionibacterium freudenreichii (without Lactobacillus acidophilus) and continuous feeding of lactose with the rate of 0. 04 l/h at 36° C in a medium containing 25 g/l molasses, 10 g/l corn steep liquor, at pH=6. 5, after 96 h fermentation. Maximum vitamin concentration (30 mg/l) and productivity (7. 5 mg/l. day) were obtained in trial 9. Organoleptic properties of the fermented beverage were also acceptable for panelists and no significant difference was observed between samples and control during 6 days refrigerated storage.

Background and objectives: In this research, production of date palm extract based functional beverage through its fermentation by lactobacillus rhamnosus during 12 weeks storage was assayed.Materials and methods: Fermentation was done at 37oC for 48h. Growth kinetics, pH, acidity, total phenolic content, and antioxidant activity were investigated during the fermentation process. In the next step, fermented date extract which was mixed with sugar and citric acid, was used to produce the functional drink.Pasteurized samples were packed in the glass and polyethylene terephthalate bottles which were transparent and opaque to indicate the light effect and then storage stability of the beverages was studied. Packages were stored at ambient and refrigerator (4oC) temperature. The samples of each treatment had been withdrawn after two weeks, up to a period of 12 weeks. Afterward following tests were performed on the samples: pH, color intensity, acidity, phenolic compounds, antioxidant activity, aerobic mesophilic bacteria, yeasts and moulds colony count. sensory evaluation was performed at the end of the shelf life.Results: The results of growth curve showed that population of L. rhamnosus reached to 108 CFU/ml after 20 h. In addition, pH of date syrup decreased to about 4.3 after fermentation, which is important because of the inhibition of undesirable bacteria growth and technological aspect. Because of the preservation of phenolic compounds and antioxidant activity, storage at 4oC, in the glass and opaque bottles is suggested. Sensory evaluation showed no significant organoleptic changes in the samples. In terms of microbiologic test, no moulds, yeasts and aerobic mesophilic bacteria contamination were observed.Conclusion: These findings suggest that date palm extract drinks should be treated as short shelf life (6 weeks as optimal) products to get the most potential health benefits of antioxidant polyphenols.