Influence of biodegradable poly(L-lactic-co-butanediol itaconate)nano-silica packaging material on storage quality and viable bacteria count of fermented yogurt
This study aimed to investigate the effect of poly(L-lactic-co-butanediol itaconate)nano-silica copolymer film packages with different barrier properties on the storage of fermented yogurt and to determine the physicochemical indexes of yogurt during storage and viable bacteria counts during storage.Results showed that during the storage period of 0-21 days at4 ℃,the pH of all packaging groups showed a decreasing trend,and the pH decrease of the PLBI-SiO2 0.5％packaging group and the control(commercially available)group was slowed down in the late-stage of the storage period;During the storage period,the PLBI-SiO2 0.5％packaging group and the control(commercially available)group were able to maintain the texture and water holding capacity of the yogurt,and the sensory evalua-tion and the apparent viscosity of the yogurt.All packaging groups were able to maintain the physical and chemical indexes and live bacte-rial counts of the yogurt during the storage period;All packaging groups had the effect of fermented yogurt storage.The viable bacterial counts of all packaging groups showed a gradual decrease throughout the storage period,but the decrease was slowed down with the im-provement of the barrier property of the packaging,and the viable bacterial counts of Lactobacillus bulgaricus and Streptococcus thermophilus in the PLBI-SiO2 0.5％packaging group and the control group both remained above 107 CFU/ml at 21 days of storage.Comprehensive in-dicators,the PLBI-SiO2 0.5％packaging group can maintain the storage quality of the yogurt and nearly compare with the commercially available packaging group at 21 days of storage,which provides a certain theoretical basis for alternative packaging materials for yogurt and other fermented milk.
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