Cellular injuries on spray‐dried Lactobacillus rhamnosus GG and its stability during food storage

Abstract

Purpose

This paper aims to evaluate the cellular injuries associated with spray‐drying of Lactobacillus rhamnosus GG (LGG) in trehalose/monosodium glutamate (MSG) media by means of flow cytometry measurements; and also whether, and to what extent, the probiotic remain stable and viable in food formulations.

Design/methodology/approach

Spray‐drying was applied in the production of trehalose‐based preparations containing LGG. To gain more insights on the cellular damages that must have occurred during drying, flow cytometric analysis was applied in combination with carboxyfluorescein diacetate (cFDA) and PI stains. Spray‐dried samples were observed by scanning electron microscopy (SEM). The storage stability of spray‐dried LGG was monitored in food samples over a period of time.

Findings

It was observed that during spray‐drying, 1.80×10⁹ CFU/ml viable counts, which were equivalent of 68.8 per cent cells, were recovered in trehalose matrices but on incorporating 12.5 g/l MSG as a carrier component, survival rates were significantly improved. Density plot analysis showed a higher degree of membrane damage in cells spray‐dried in trehalose without MSG. SEM revealed no difference in the shapes and surfaces of spray‐dried samples. Evaluation of the recovery rates of LGG, initial count of ∼10⁹ CFU/ml or g, at storage time intervals revealed a minimum level of ∼10⁵ CFU/ml in apple juice after 12 days and ∼10⁷ CFU/g in chocolate beverages after ten weeks.

Originality/value

The potential contribution of MSG as a carrier component with trehalose in preventing higher losses during spray‐drying and food storage is pointed out in this study.

Citation

Oluwaseun Sunny‐Roberts, E. and Knorr, D. (2011), "Cellular injuries on spray‐dried Lactobacillus rhamnosus GG and its stability during food storage", Nutrition & Food Science, Vol. 41 No. 3, pp. 191-200. https://doi.org/10.1108/00346651111132466