EFFECT OF FERMENTATION ON THE NUTRIENT COMPOSITION, INVITRO PROTEIN DIGESTIBILITY AND ANTIOXIDANT PROPERTIES OF OPAGHA SEED (Pentaclethra macrophylla).

Abstract

Spontaneous fermented as well the unfermented seeds of Pentaclethra macrophylla (Opagha seeds) found mostly in all the remote villages in the southern part of Nigeria were analysed for their proximate composition, energy values, minerals contents, functional properties, anti-nutrients, amino acid profile ,vitamins, in-vitro protein digestibility as well as fatty acid profile of the seed oils.The unfermented opagha seeds contained on the average (g/100g) 11.84,crude protein(CP),3.80 ether extract (EE),3.64 crude fibre(CF),3.00 ash,68.29 nitrogen free extract(NFE).Natural fermentation increased CP,EE,CF and ash to 3.95,4.85 and 3.39g/100g respectively and increased values for CP and CF in microbially fermentation are 12.68 and 4.57g/100g respectively. The values for ash was the highest in the unfermented seeds 61.80g/100g and lowest in naturally fermented seeds 51.69g/100g with co-efficient of variation(CV) of 61.80%.Gross energy (kcal/100g) was highest in unfermented 376.7 and lowest 287.91kcal/100g in naturally fermented seeds. Both methods of fermentation processes generally enhanced the concentration of both trace and major minerals. The coefficient of variation (CV) in mineral content due to fermentation ranged from 4.78% in Na to 58.33% in selenium. The concentration of Fe was most affected by fermentation. The mean values for water absorption capacity (WAC), oil absorption capacity (OAC), emulsion capacity (EC), emulsion stability (ES), foaming capacity (FC), foaming stability (FS) 9.65,0.51,4.17,4.81,3.29 and 4.11% respectively. Both natural and microbial fermentation enhanced WAC, ES and EC while other functional attributes were not markedly affected. Protein solubilities of the fermented seeds were generally high in both acidic and alkaline media. The polyphenolic compound were significantly reduced when compared to the concentration in unfermented seeds. Opagha seeds generally contained good array of amino acids. However, microbially fermented seeds tends to have higher concentration particularly of alanine, serine, proline, valine, threonine, leucine, lysine, Ph-Alanine and histidine. The thin layer Gas Chromatographic analysis of the seed oils revealed the presence of fatty acids varying from C1 to C18 mean values ranged from 0.19% in erucic acid to 64.02% in linolenic acid. Among all the vitamins analysed vitamin C ranged 2.02mg/100g in unfermented seeds to 2.24mg/100g in microbially fermented seeds. The in-vitro multi-enzymes digestibility indicated that the microbilally fermented seeds 67.47% were more digestible than the naturally fermented and unfermented 65.66%. It was recommended that the controlled fermentation either natural or microbial methods may be used to modify the chemical and functional attributes of these seeds for different end uses.