Abstract This article focuses on increasing the shelf life of both pasteurized (Pa) and traditional (Tr) butters wrapped in Ag-Low Density Polyethylene (LDPE) film in concentration of 2.5%, 7.5%, 12.5%, and 17.5% at refrigerated temperature up to one month. Silver nanoparticles were synthesized (20.63 nm) through the chemical reduction followed by the melt mixing method to produce Ag-LDPE films. A mixed model-ANOVA Repeated Measurement presented that total bacteria, S. aureus and E. coli were eliminated from the Pasteurized butter samples wrapped with 17.5% Ag/LDPE films. In comparison, psychrophilic bacteria can be eradicated by 2.5-17.5% Ag/LDPE films after 30d. Peroxide value showed a slight fall from 0.50 and 0.28 meq/kg, respectively for Pa and Tr butters on the 1st day in the control group to 0.31 and 0.24 meq/kg, respectively in the butter wrapped with 17.5% Ag-LDPE film at the end of the storage with no significant difference (p > 0.05) with other treatments. Iodine value was decreased after 30d. It is concluded that the use of 17.5% Ag/LDPE as a coating of butter can safely preserve pasteurized butter at least a month.

Abstract The aim of this study was to investigate the probiotic characteristics profile of the isolated lactic acid bacteria (LAB) isolated from cow milk enzymatic clots. Some criteria for probiotic potential such as fermentation profile, acid and bile tolerance, bile salt hydrolysis, antimicrobial activities, lactic acid and bacteriocin production assay, acidification and coagulation, and hemolytic properties were examined. 16S rDNA-based method was applied to confirm the identity of the isolated LABs. LAB E showed the highest resistance to acidic environments. In bile conditions, the number of LAB B and D colonies was also significantly reduced from about 107 to 102 after 1 hour and to less than 100 after 2 and 4 hours. None of the strains showed sensitivity against fungal and microbes except Escherichia coli. This study showed that LABs B, E, and G isolated from cow milk enzymatic clots presented good properties to consider as probiotics and to use for the production of probiotic dairies.

Abstract The present study was conducted to characterize poly (lactic acid) ‐Lippia citriodora and Laurus nobilis essential oils (EOs) and Nanoemulsion-based films. Following Gas chromatography–mass spectrometry and in vitro antimicrobial activity test, 12% of Nanoemulsions of both herbs were selected for further evaluations. Accordingly, Atomic Force Microscopy and Dynamic light scattering analysis showed that the scale sizes of Nanoemulsions of L. citriodora and L. nobilis were 24-60 and 15-28 nm, respectively with no significant changes in their PDI up to 90 d. The inhibition zone of both herbs against E. coli and Staphylococcus aureus alongside MIC and MBC tests showed higher efficiency in their nanoemulsions. In conclusion, two types of incorporated PLA/L. citriodora films could effectively extend the shelf life of rainbow trout fillet at refrigerated temperatures.

Abstract The present study was aimed to determine the effects of Lactobacillus acidophilus LA-5, L. paracasei 431, and Bifidobacterium lactis BB-12 with lactulose on values of conjugated linoleic acid (CLA) and microbial, physicochemical, and sensory properties of a novel kefir. Thirteen groups were evaluated on days 1, 7, and 14 at 4 oC. The interaction between probiotics and lactulose reduced pH to 4.5 in the first week and slightly decreased on day 14 (4.35). The syneresis value was decreased by increasing the lactulose dose. The interaction could not remarkably increase probiotic survival; the greatest and lowest values were 7.18 and 7.81 log CFU/mL, respectively. The greatest and the lowest lactic acid value was 2.77 and 1.47 g/100 mL, respectively, in kefirs supplemented with L. acidophilus LA-5 and L. acidophilus LA-5+ L. paracasei 431+ B. lactis BB-12. A 4-fold increase in the acetic acid value (0.592 g/100 mL) was observed in kefirs supplemented with B. lactis BB-12 along with L. acidophilus LA-5 and L. paracasei 431 (G12). It is concluded that adding 5% lactulose along with L. acidophilus LA-5+ L. paracasei 431 to kefir could valuably increase the CLA value (3.51-8.07 ppm) and give it more acceptability of flavor, odor, and syneresis.

Abstract The nanosilver food packaging films were developed by polyvinyl alcohol activated with Satureja rechingeri extract (S-AgNPs/PVA) using the solvent casting to evaluate the freshness of Oncorhynchus mykiss fillets during 14 days at the refrigerated temperature. The 160 pieces of fish were enfolded in 4 types of films as main group-series. The main components of the extract were carvacrol (83.2%) p-cymene (3.11%), thymol (2.13%) and γ-terpinene (1.63%). The UV-Vis and TEM evaluations of S-AgNPs showed that the size of S-AgNPs was mostly smaller than 55 nm in diameter. Mesophilic and psychrophilic bacteria counts were remarkably less than 6.0 log CFU/g about 2.1, 1.3 log CFU/g and 2.0, 1.0 log CFU/g, respectively for fish samples wrapped in S-AgNP/Ult.PVA (Ultrasound method) and S-AgNP/Pho.PVA (Photochemical method) preserved at 4 °C on the 7th day. S-AgNP/Ult.PVA and S-AgNP/Pho.PVA showed strong efficiency in complete eliminating S. aureus and psychrophilic bacteria from coated trout samples than E. coli and mesophiles. It is suggested that AgNP/Ult.PVA and S-AgNP/Pho.PVA films can be used as nanocomposite film for fish preservation at refrigerated temperature to postpone the spoilage up to 7th day.