Study on heat-resistant powder of Lactobacillus plantarum microcapsule

Abstract

Objective: This study aimed to improve the heat tolerance of Lactobacillus plantarum. Methods: On the basis of the previous research on the microcapsule emulsion, a kind of powder was prepared by spray drying with 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD). The response surface method is used to optimize different parameters. Its morphology was observed by light microscope and electron microscope, and the particle size was determined by laser particle size analyzer and Zeta potential analyzer; the absorbance change was measured by spectrophotometer, and heat resistance test was carried out by oven heating. Results: With the increase of the ratio of 2-HP-β-CD to emulsion mass, feed rate, inlet air temperature and inlet air rate, and the survival rate first increased and then decreased (P＜0.05). By response surface methodology, the optimal parameters of spray drying were obtained as follows: the ratio of 2-HP-β-CD to emulsion mass 3.13, feed rate 288 mL/h, inlet air rate 112 m3/h and the inlet air temperature 118 ℃. Under the control fo these conditions, the survival rate of bacteria was (99.53±0.11)%, and the bacterial load reached 1.64×109 CFU/g. The scanning electron microscopy and microscopy results showed that the microcapsule was a central concave particle, spherically dispersed in water with the bacteria gathered inside. The absorbance value of the water dispersion was not found changing significantly within 1 h (P＞0.05), and the average particle size was 472.7 nm with distribution concentrated and Zeta potential at -40.37 mV. The survival rate of microcapsules was 96.79% when treated at 130 ℃for 60 s, which was significantly different from the survival rate of bacterial sludge (P＜0.01). Conclusion: The microcapsule powder has high heat resistance and stable water dispersibility.

Keywords

• lactobacillus plantarum
• microcapsule powder
• spray drying
• heat tolerance
• survival rate