EVALUATION OF MICROORGANISMS AND PHYSICOCHEMICAL CHARACTERISTICS OF UNRIPE PAWPAW (CARICA PAPAYA LINN.) FRUITS DURING FERMENTATION

Abstract

Pawpaw (Carica papaya Linn) is a popular and important fruit tree, the whole plant parts, from the fruit to the pulp, are also known to have medicinal properties. The study investigated the microorganisms in fermented unripe pawpaw (Carica papaya Linn) fruits and determined the efficacy and potentials of broth associated microorganisms of the fruit against selected clinical isolates using albino rats. Samples of about 55 unripe pawpaw fruits were collected from pawpaw plants located in the Federal University of Technology, Akure, Nigeria. The samples were prepared and divided into fourteen portions, seven portions of the pawpaw peels and seven portions of the pawpaw fruits. They were fermentation for a period of seven days. Microbiological analysis was carried out on the samples for each day. Physiochemical analyses, proximate, mineral, antioxidant and antinutritional compositions of samples were determined using standard technique. Microorganisms were isolated, identified and screened for production of enzymes using standard methods. The antimicrobial activity of the fermented materials was tested against pathogenic organisms. The investigation was carried out using Swiss albino rats; the rats were screened to confirm the absence of any pathogenic infection before being used for the experiment. They were then infected with the pathogenic organisms and treated with the fermented pawpaw fruit broth. The pH value during the fermentation ranged from 2.22 to 6.04, titratable acidity ranged from 0.40 to 7.20% and 0.02-0.13g/ml for water absorption capacity of the samples. The samples revealed concentrations of proximate, mineral and antinutritional content as well as antioxidant properties. Phytochemical screening showed the presence of Tannins, Saponins, Flavonoids, Anthraquinones, Cardiac glucosides and Alkaloids. Bacteria isolated include; Leuconostoc mesenteroides, Bacillus subtilis, Listeria monocytogenes, Lactobacillus brevis, Micrococcus luteus, Staphylococcus aureus, Bacillus cereus, while fungi isolates were Mucor mucedo, Rhizopus stolonifer, Aspergillus niger, Aspergillus flavus, Penicillium notatum, Saccharomyces cerevisae, Candida tropicalis, Aspergillus funmigans. Leuconostoc, Bacillus, Lactobacillus, Micrococcus, Staphylococcus species predominated for the bacteria isoaltes while Apergillus and Mucor, predominated for Fungi. Saccharomyces cerevisae and Candida tropicalis were isolated for yeast in the fermenting broth. The fermentation process improved the quality characteristics of the fermented materials thereby enhancing the antimicrobial activity and also the breaking down of the antinutrient properties in the unripe pawpaw fruits. The findings from the study revealed that the fermented unripe pawpaw broth could be used to treat albino rats specimens that had beeninfected with enteric pathogenic microorganisms and the rats showed positive response after two days of treatment. This could be as a result of the phytochemical constituents present in the fermented broth.