Effect of Drying Process, Encapsulation, and Storage on the Survival Rates and Gastrointestinal Resistance of L. salivarius spp. salivarius Included into a Fruit Matrix.

Ester Betoret,Laura Calabuig-Jiménez,Noelia Betoret,Cristina Barrera,Marco Dalla Rosa

doi:10.3390/microorganisms8050654

Abstract

In a new probiotic food, besides adequate physicochemical properties, it is necessary to ensure a minimum probiotic content after processing, storage, and throughout gastrointestinal (GI) digestion. The aim of this work was to study the effect of hot air drying/freeze drying processes, encapsulation, and storage on the probiotic survival and in vitro digestion resistance of Lactobacillus salivarius spp. salivarius included into an apple matrix. The physicochemical properties of the food products developed were also evaluated. Although freeze drying processing provided samples with better texture and color, the probiotic content and its resistance to gastrointestinal digestion and storage were higher in hot air dried samples. Non-encapsulated microorganisms in hot air dried apples showed a 79.7% of survival rate versus 40% of the other samples after 28 days of storage. The resistance of encapsulated microorganisms to in vitro digestion was significantly higher (p ≤ 0.05) in hot air dried samples, showing survival rates of 50–89% at the last stage of digestion depending on storage time. In freeze dried samples, encapsulated microorganisms showed a survival rate of 16–47% at the end of digestion. The different characteristics of the food matrix after both processes had a significant effect on the probiotic survival after the GI digestion. Documented physiological and molecular mechanisms involved in the stress response of probiotic cells would explain these results.

Highlights

Juices, fruits, vegetables, breads, and cereals fiber snacks are the main options being studied in the area of probiotic functional foods as an alternative to dairy products [1]
It is generally accepted that to have an evident effect, probiotic foods should have a minimum concentration of 106 CFU/mL or gram, or a total consumption of 108–109 colony forming units (CFU) per day depending on the microorganism strain and the physiological conditions of the host [2]
That the probiotic microorganisms would exert a beneficial effect on the host, they should survive the stresses suffered during all food production processing and storage but they should resist the passage through the gastrointestinal tract to be delivered in the active form to the specific target point [3]

Summary

Introduction

Fruits, vegetables, breads, and cereals fiber snacks are the main options being studied in the area of probiotic functional foods as an alternative to dairy products [1]. That the probiotic microorganisms would exert a beneficial effect on the host, they should survive the stresses suffered during all food production processing and storage but they should resist the passage through the gastrointestinal tract to be delivered in the active form to the specific target point [3]. The incorporation of probiotics into a fruit matrix, besides developing a new probiotic food products category, could protect the microorganisms from the stresses suffered during processing, storage, and the gastrointestinal (GI) digestion [6]. The aim of this work was to study the effect of the two drying processes most commonly applied in the food industry, encapsulation, and storage on the physicochemical properties, the probiotic survival, and in vitro digestion resistance of Lactobacillus salivarius spp. salivarius included into an apple matrix

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Conclusion