Abstract
Agro-industrial by-products are promising source of biopolymers, including proteins and polysaccharides. This study was designed to evaluate the flaxseed oil cake extract (FOCE) as natural encapsulating material and carrier for probiotic Lacticaseibacillus rhamnous GG (LGG). The powders were obtained using three spray drying inlet temperatures (110 °C, 140 °C, 170 °C), and reconstituted. The influence of temperature on water activity, morphology, chemical composition, flowability and cohesiveness of the powders was estimated. For all variants, the survival of bacteria during spray drying, and simulated passage through the gastrointestinal tract was evaluated. The preservation of LGG probiotic features such as cholesterol reduction, hydrophobicity and adhesion to mucin were examined. Results revealed that all physicochemical and functional characteristics of the powders were affected by the inlet temperature. This study demonstrated that FOCE is an appropriate matrix for spray drying (due to flaxseed proteins and polysaccharides) providing high survivability of bacteria (89.41-96.32%), that passed meaningfully through the simulated gastrointestinal tract (4.39-5.97 log reduction), largely maintaining their probiotic properties, being a promising environmentally-friendly carrier for probiotic LGG.
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Key Points
The full use of FOCE (flaxseed oil cake extract) is a relatively new. FOCE is a liquid mixture obtained by hot extraction from FOC, the main components of which are primarily protein (FP—flaxseed protein) and mucilage (also known, as flaxseed gum—FG), abundant also in antioxidants. A feature of FG is the formation of a multiform structure and increase the resistance of multiphase systems to environmental stresses, thus FG can be used as a thickener, stabilizer, gelling agent and emulsifier. Flaxseed mucilage shows good prebiotic potential, that can protect LAB cells from the adverse gastric environment and digestion. FOCE (used as liquid matrix or spray-dried powders) can be used as a stabilizing agent due to the synergistic effect of FP and FG. FOCE could act as an effective encapsulating agent and carrier for LAB, due to its biopolymers (proteins and polysaccharides) content.
The objective of this research was to valorize spray-dried FOCE as a natural carrier for probiotic LGG. Particularly, this study was designed to evaluate the influence of the spray drying process on powders properties as well as viability and probiotic properties of LGG in initial and reconstituted FOCE under simulated conditions of the GIT.
The findings of this study confirmed that FOCE has a good potential to be considered as an encapsulating agent and natural carrier for probiotic Lacticaseibacillus rhamnosus GG. Due to biopolymers (flaxseed proteins and polysaccharides) content FOCE provided high survivability of LGG cells, that passed meaningfully through the simulated gastrointestinal tract, largely preserved their probiotic properties. However, further in vivo studies, including human clinical trials of matrix combinations and doses in different populations, are needed to confirm the health benefits of LGG in FOCE. In addition, further in-depth studies to demonstrate the effect of spray drying and reconstitution on the physicochemical properties, bioactivity and matrix biopolymers interactions of FOCE should be carried out.