Kinetic behaviors of five Lactobacillus strains were investigated with Contois and Exponential models. Awareness of kinetic behavior of microorganisms is essential for their industrial process design and scale up. The consistency of experimental data was evaluated using Excel software. L. bulgaricus was introduced as the most efficient strain with the highest biomass and lactic acid yield of 0.119 and 0.602 g g−1 consumed lactose, respectively. The biomass and carbohydrate yield of L. fermentum and L. lactis were slightly less and close to L. bulgaricus. Biomass and lactic acid production yield of 0.117 and 0.358 for L. fermentum and 0.114 and 0.437 g g−1 for L.actobacillus lactis were obtained. L. casei and L. delbrueckii had the less biomass yield, nearly 11.8 and 22.7% less than L. bulgaricus, respectively. L. bulgaricus (R2 = 0.9500 and 0.9156) and L. casei (R2 = 0.9552 and 0.8401) showed acceptable consistency with both models. The investigation revealed that the above mentioned models are not suitable to describe the kinetic behavior of L. fermentum (R2 = 0.9367 and 0.6991), L. delbrueckii (R2 = 0.9493 and 0.7724) and L. lactis (R2 = 0.8730 and 0.6451). Contois rate equation is a suitable model to describe the kinetic of Lactobacilli. Specific cell growth rate for L. bulgaricus, L. casei, L. fermentum, L. delbrueckii and L. lactis with Contois model in order 3.2, 3.9, 67.6, 10.4 and 9.8-fold of Exponential model.

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Saccharomyces cerevisiae PTCC5269 growth was evaluated to specify an optimum culture medium to reach the highest protein production. Experiment design was conducted using a fraction of the full factorial methodology, and signal to noise ratio was used for results analysis. Maximum cell of 8.84 log (CFU/mL) was resulted using optimized culture composed of 0.3, 0.15, 1, and 50 g L(-1) of ammonium sulfate, iron sulfate, glycine, and glucose, respectively at 300 rpm and 35 °C. Glycine concentration (39.32 % contribution) and glucose concentration (36.15 % contribution) were determined as the most effective factors on the biomass production, while Saccharomyces cerevisiae growth had showed the least dependence on ammonium sulfate (5.2 % contribution) and iron sulfate (19.28 % contribution). The most interaction was diagnosed between ammonium sulfate and iron sulfate concentrations with interaction severity index of 50.71 %, while the less one recorded for glycine and glucose concentration was equal to 8.12 %. An acceptable consistency of 84.26 % was obtained between optimum theoretical cell numbers determined by software of 8.91 log (CFU/mL), and experimentally measured one at optimal condition confirms the suitability of the applied method. High protein content of 44.6 % using optimum culture suggests that Saccharomyces cerevisiae is a good commercial case for single cell protein production.

Antibacterial packaging is introduced as a new method to prevent microbial food spoilage. Antibacterial effects of TiO2, ZnO and mixed TiO2–ZnO nanoparticle‐coated low‐density polyethylene (LDPE) films on Escherichia coli PTCC1330 were investigated. Bactericidal efficiency of 0.5%, 1% and 2% TiO2 and ZnO nanoparticles and also 1% mixed TiO2–ZnO nanoparticles with ratios of 25/75, 50/50 and 75/25 were tested under ultraviolet (UV) and fluorescent lights at two states: films alone and fresh calf minced meat packed. Maximum colony‐forming unit (CFU) reduction of 99.8% and 99.7% were obtained using 1% and 2% ZnO nanoparticle‐coated LDPE film under fluorescent light for films alone as well as 99.8% and 99.6% for fresh calf minced meat packed. 90.3% and 51.8% CFU reduction were recorded for 1% TiO2 nanoparticle‐coated LDPE films in the presence of UV light at direct contact with bacteria and fresh calf minced meat packed, respectively. Maximum CFU reductions of 96% and 64.1% were obtained using 50/50 ratio of TiO2/ZnO nanoparticles at the presence of UV light for film alone and fresh calf minced meat packed, respectively. ZnO nanoparticle‐coated LDPE films were identified as the best case to improve shelf life and prevent E. coli growth in fresh calf minced meat.