PROBIOTIC PROPERTIES OF LACTIC ACID BACTERIA ON FERMENTED FRUITS IN THE BUEA MUNICIPALITY

ABSTRACT

Probiotic products are marketed widely throughout the world. This is especially true of yogurts that contain strains of lactic-acid bacteria of intestinal origin. Consumption of these products is aimed at promoting the wellbeing of the consumer by impacting on the collection of microorganisms that normally inhabit the intestinal tract. The development of scientifically valid probiotics requires more detailed knowledge of this intestinal micro flora than is currently available

CHAPTER ONE

INTRODUCTION AND LITERATURE REVIEW

INTRODUCTION

Lactic acid bacterial (LAB) strains belong to beneficial bacteria. They are normal inhabitants of the healthy gut microbiota and present in numerous fermented dairy products such as cheese and fermented milk, palm wine. Some like Lactobacillus, Streptococcus, Pediococcus, and Enterococcus are cultivable and predominant microbes in fermented dairy products, and exert a positive role in human health following oral administration. They improve the balance of the microbial community in the intestine, confer protection against potential pathogenic bacteria, and prevent and/or cure intestinal diseases. These effects are mediated by production of antimicrobial metabolites such as organic acids (for example lactate, acetate, and butyrate), hydrogen peroxide, and bacteriocins, and competition with harmful bacteria for nutrients or adhesion receptors.           The therapeutic effects of the beneficial microorganisms include, but are not limited to, enhanced immune function, maintenance of anti-tumor activity, reduction of the population of harmful microorganisms, improvement of the balance of microflora in the colon, prevention against some intestinal infection, increased tolerance to lactose-containing foods, and possibly prevention of cancer

LITERALLY REVIEW

Lactic acid bacterial (LAB) is a diverse bacteria group of 11 genuses. These bacteria gram positive, non-spore forming cocci or rods but aerotolerant, able to berment carbohydrate into lactic acid and energy LAB produces various compounds such as organic acid, diacetyl, hydrogen peroxide and bacteriocins or bacteria protein during lactic acid fermentation. Bacteriocins are peptides produced by a variety of microbs and have antimicrobial activity against closely related species. These antimicrobial agents gaining more and more attention as an alternate therapeutics not only in pharmaceutical but also as a preservative in food industries the main aim of this view is to highlight LAB in fermented food samples.

LABS belong to the phylum Firmicutes. The different genera include: lactobacillus weissellalactococcus, melissococcus, Enterococcus, leuconostoc pediococcus, streptococcus vagococcus carnobacterium and tetragenococcus. LAB constitute the highest percentage of bacteria that produces probiotic properties.

 Probiotics can be defined as mono or mixed culture of living microorganisms which beneficially affects the host [Humans and Animals] by improving the balance of indigenous microflora, when consumed in adequate amount as part of the food. In foods, LAB has different usage which includes inhibition of the growth of pathogens, enhance food nutritive quantity and extending the shelf life of food.

Lactic acid fermentation represents the easiest and the most suitable way for increasing the daily consumption of fresh-like vegetables and fruits. Literature data are accumulating, and this review aims at describing the main features of the lactic acid bacteria to be used for fermentation. Lactic acid bacteria are a small part of the autochthonous microbiota of vegetables and fruits. The diversity of the microbiota markedly depends on the intrinsic and extrinsic parameters of the plant matrix. Notwithstanding the reliable value of the spontaneous fermentation to stabilize and preserve raw vegetables and fruits, a number of factors are in favour of using selected starters. Two main options may be pursued for the controlled lactic acid fermentation of vegetables and fruits: the use of commercial/allochthonous and the use of autochthonous starters. Several evidences were described in favour of the use of selected autochthonous starters, which are tailored for the specific plant matrix. Leuconostoc spp., Lactococcus spp., Lactobacillus spp., and Streptococcus thermophilus are examples of LAB that can convert sugars into lactic acid. Lactic acid inhibits the growth of subsequent and potentially harmful bacteria of other species and creates favorable conditions for yeast activity, a property utilized in the production of wine and beer. In winemaking, LAB are present throughout all stages, and they can either enhance or diminish the quality of wine through malolactic fermentation and affect the organoleptic properties of the final product. The concentration of LAB during malolactic fermentation reaches approximately 10⁷ CFU/mL, which indicates their importance in winemaking. The density of LAB in the initial phases of winemaking ranges from about 10³ to 10⁴ CFU/m. The most abundant are Lactobacillus hilgardii, L. plantarum, L. casei, Leuconostoc mesenteroides, and Pediococcus damnosus, while less common species include Oenococcus oeni and Lactobacillus brevis

Lactic fermentation can be used in the beverage industry to enhance antioxidant and antimicrobial properties or produce probiotic beverages. Muhialdin et al.tested the effect of dragon fruit juice fermentation with L. plantarum on consumer acceptability and biological activity of the final product. The results show that fermentation at 37 °C for 48 h enhanced the antibacterial activity of fermented dragon fruit juice threefold. As per acceptability, consumers preferred the mixed dragon fruit fermented juice with fresh juice in the 1:9 ratio, as the fermented juice was too sour, with low pH (3.49). Additionally, this beverage had an extended shelf life to 3 months with no detected odors, color, and taste modifications compared to the fresh dragon fruit juice, which developed an unpleasant aroma and taste only after 1 month of storage at 8 °C.

RATIONALE

        The use of probiotics in the food samples such as yoghurt has been increased as potential alternatives to probiotics used as growth promoters. In this case the development of effective probiotics products that can be licensed for man’s consumption and continues to receive attention. For this reason the study of, isolate and characterization of lactic acid bacteria from food sample are important to man in food because its presence shows the ability of the resistance to enteropathogenic organisms. Therefore the rational of this study is based mainly on food matter, the antibacterial activity and susceptibility to antibiotics.

HYPOTHESIS

HO: Lactic acid bacteria do not cause fermentation in fruits/ food.

H1: lactic acid ferment fruits and food substances (alternative hypothesis)

OBJECTIVES

Overall objective: To determine the activity of probiotic substances in fruits and food.

Specific objective: To identify the probiotic properties of lactic acid bacteria on fruits/food.