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 This study aimed to examine the production of a synbiotic yogurt sauce and to evaluate its physicochemical, microbiological, sensory, and rheological properties during storage. Lactobacillus paracasei was microencapsulated with resistant starch and sodium alginate by the emulsion technique. Two forms of probiotic bacteria (microencapsulated and free), together with prebiotic compounds (flaxseeds and chia seeds each one at two concentrations of 2% and 4%), were added to the yogurt sauce. Samples were kept for 30 days at 4 ˚C and observed for physicochemical, microbiological, sensory, and rheological characteristics within specific intervals. The results revealed that the produced synbiotic yogurt sauce was characterized as a pseudoplastic fluid. However, its viscosity increased due to the presence of flaxseeds and chia seeds. The addition of flaxseeds and chia seeds improved the survival of bacteria. The post-acidification values were lower in samples containing the microencapsulated bacteria compared to samples containing the free bacteria. Among the produced samples, the highest acceptable score for the sensory characteristic was obtained for the sample containing microencapsulated L. paracasei and 2% flaxseeds. Therefore, it is possible to produce a synbiotic yogurt sauce with desirable properties.

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.