Assessment of viability of probiotic bacteria in non dairy food matrices under refrigeration storage

Functional foods serve nutrients and physiologically active components for a healthy living. In most countries, the products related to having a healthy gut dominate the functional foods market. These products are prebiotics, probiotics and synbiotics. Concerning the health benefits, various probiotics are introduced to food matrices. Though dairy is the ideal food matrix for probiotics, the trend of non-dairy probiotics is growing among consumers.;This study included two research objectives: surveying the commercial probiotic containing products for probiotic level and developing a practical home-made probiotic fermentation process. The first part of this study was mainly based on assessing viability of probiotic bacteria in non-dairy matrices. Six commercially available probiotics products were tested to verify the manufacturer compliance with the claimed amount on the labels under refrigeration storage for the recommended shelf life. Five products were non-dairy matrices including both liquid and solid matrices. One was a dairy substrate. Viability was assessed by plate counting and flowcytometry. Flowcytometry analysis followed by staining with Live/Dead BacLight Viability Kit, did not provide consistent acceptable counts. Therefore viable counts by plate counting were compared with the manufacturer claims. All products were in the acceptable range for therapeutic minimum (106-108 CFU/ml or CFU/g). However, four products had significantly (p<0.05) lower counts than the manufacturer claims. When the stability during the refrigeration temperatures is concerned, fruit juice (blackberry - pomegranate) and chocolate were more stable food matrices.;The second part of this study was based on developing a novel food product based on fermented coconut water and oatmeal. For the safety, commercial coconut water and oatmeal were used; L. plantarum Lp 115-400B, which is a proven probiotic, was used as the starter culture. The evidence of some unpublished studies, that revealed fermented coconut water possesses some healing power of unusual bowel movements led us to use coconut water as the fermentation substrate. Oatmeal-coconut water matrix was inoculated with 107 CFU/g of L. plantarum to have the novel mixture. Fermentation kinetics was obtained by evaluating the viability at 24, 32, 27, 42 and 47 ºC at 2h intervals using Arrhenius equation. For the preparation of the fermented product, 27 ºC was used with 10h fermentation (n=3). The experiment was designed as a split plot block design. The fermented product was refrigerated (4+/-1 ºC) and viability of L. plantarum was enumerated weekly by plate counting. The recommended minimum daily dose of inulin (1g) was added to the same matrix and viability was compared with the samples without inulin (n=3). Both pH and total acidity of the matrix were also monitored weekly. The apparent viscosity was measured on the production day (day 0) and on the last test day (day 49). The inulin dose used in this study does not affect the viability of selected L. plantarum strain within this matrix. The shelf life of the novel food matrix was determined by counting the days taken to reach 107- CFU/g. Shelf life was 7 weeks without inulin and with inulin it was 5 weeks. A significant reduction of pH was observed at the end of the considered shelf life. The apparent viscosity of the product did not change significantly (p>0.05) after the fermentation.;In conclusion, out of six commercial products, five products do not deliver the claimed probiotic counts by the manufacturer at the end of the shelf life. The fermented novel food matrix sustains L. plantarum for 7 weeks at successful levels under refrigeration.