Acta Scientiarum Polonorum Technologia Alimentaria

Background. Prebiotics provide a survival advantage to probiotics over pathogens. There is a need to iden­tify novel sources of prebiotics that can be introduced into daily diets. In the present study, Citrus seeds were identified as a promising source of prebiotics. A combination of probiotics and prebiotics is termed synbiot­ics; however, crude mixtures fail to last in the gastro-intestinal environment. Microencapsulation is a means of ensuring the stability and effectiveness of synbiotics. When encapsulated synbiotics are introduced into food vehicles, the latter are termed functional foods. The aim of the present paper is to ascertain the shelf-life stability of a functional tomato sauce fortified with encapsulated synbiotics.

Materials and methods. Polar solvents were used to extract the low molecular weight carbohydrates (LMWC) from Citrus seeds. The prebiotic activity of the extracts was quantified and they were packed with Lactobacillus acidophilus (L. acidophilus) (ATCC4356) into microcapsules using emulsion and extrusion techniques. An SEM study was carried out to test the stability and quality of the microcapsules. They were stably integrated into a sauce. The shelf-life of the sauce (pH, acidity, soluble solids, salt content) and release of probiotics from the microcapsules were tested over a period of 50 days. The safety of the food product for consumption was also established.

Results. A positive prebiotic activity score (PAS) of 11.25 was recorded for the LMWC extracted from Ci­trus seeds, confirming their preferential utilization by probiotics. The extrusion beads and emulsion capsules imparted a soft texture to the product. The water activity values of extrusion beads and emulsion capsules were 0.541 and 0.428 respectively, suggesting a lack of contamination by microbial growth. The salt content in the sauce was approximately 1.5% throughout the study. Up to 20 days of storage the acidity decreased and the soluble solids concentration increased. Syneresis was seen to start on the 35th day of storage at cool temperatures, which caused apparent changes in the biochemical parameters of the sauce. Lactobacilli were viable even on the 50th day; however, a decrease in their growth was observed.

Conclusion. Citrus seed extracts are hitherto unexplored as sources of prebiotics. Two methods of micro­encapsulation (emulsion and extrusion) were tested to carefully pack the probiotics and prebiotics. The uti­lization of tomato sauce as a food vehicle was challenging since its low pH had the potential to cause the destabilization of the encapsulation. However, the robustness of the emulsion method was verified, as it yield­ed a greater CFU/mL of probiotics on release right up to the end of the shelf-life study. Further, the capsules did not affect the textural properties of the sauce in a way that would hinder consumer choice. In the future, this work could be extended with in vivo studies to establish the bio-utility of the encapsulated synbiotics.