Effect of freezing temperature before freeze-dryer on the survival of Lactobacillus plantarum

BACKGROUND AND OBJECTIVESAlthough freeze-drying is an excellent method for preserving microorganisms, it inevitably reduces cell activity and function to some extent, as with other driers. In addition, probiotic strains differ in their sensitivity to the freeze-drying process. Therefore, it is necessary to check the parameters related to this process. The freezing temperature before freeze-drying is an important parameter in the freeze-drying process, but it is not known whether the optimal freezing temperature before freeze-drying affects survivability of probiotics.MATERIALS AND METHODSIn this study, the bacterium Lactobacillus plantarum PTCC ۱۰۵۸, obtained from the Iranian Research Organization for Science and Technology, was used, and the effects of two different freezing temperatures -۸۰ and -۲۰°C, before freeze-drying, were investigated on the survival rate of different strains of Lactobacillus plantarum after freeze drying in the presence of Carriers of malt extract and maltodextrin.RESULTS AND DISCUSSIONAccording to this study, freezing at -۸۰°C before the freeze-dryer showed a higher survival rate due to faster freezing and preventing the formation of more ice crystals in the bacterial cells. Similar studies have shown that pre-freezing temperature affects viability through changes in cell membrane integrity, membrane permeability and lactate dehydrogenase activity.CONCLUSIONIn summary, the pre-freezing temperature is an important factor in the survival of L. plantarum, and the survival of this bacterium is due to a lower probability of membrane damage due to the absence of intracellular ice crystals in the faster freezing that occurs at -۸۰ degrees.

کلیدواژه ها:

Lactobacillus plantarum ، pre-freezing temperature ، freeze-drying ، survival