NUTRITIONAL QUALITY AND PROBIOTICATION OF CONOPHOR (Tetracarpidiun conophorum) SEEDS AS AFFECTED BY PROCESSING

Abstract

This study evaluated raw and processed (as eaten) Conophor (Tetracarpidium conophorum) seeds for nutritional adequacy, probiotic potentials and histological safety. Freshly harvested conophor nuts were processed by cooking (at 100oC for 90 minutes) and toasting (at 145oC for 50 minutes). Raw nuts served as the control. The seeds were dried (at 60oC for 8 hours) and pulverized; oils were also obtained from each sample. Proximate chemical composition, mineral elements, antinutritional factors and amino acid compositions of the seed flours were determined. Oils extracted from the seed flours were analyzed for physicochemical properties, fatty acid profile and sterol composition. The oils and a commercially available vegetable oil (Executive Chef) were fed to groups of albino rats over an experimental period of twenty-eight days. The serum lipid profile [Total cholesterol (TC), α-Lipoprotein (HDL-C), β-Lipoprotein (LDL-C) and Triglycerides (TG)] of the blood obtained from the animals upon sacrifice was determined. Organs (heart and liver) excised from the animals were subjected to histological assay. Conophor creams were produced from the cooked and toasted samples and then innoculated with Lactobacillus acidophilus (C1 and T1); Lactobacillus plantarum (C2 and T2) singly and in co-culture (C3 and T3) to obtain a probioticated conophor cream which was stored at 5oC. The viability of these probiotics was investigated over a 28-day period at intervals of 7 days from the point of production. The results of the proximate composition show a high fat content with values ranging from 63.44 to 65.22g/100g dry weight. The most abundant mineral element in the seed flours was potassium, followed by calcium and phosphorus. Heavy metals (Pb, Hg, As, Cd, Co, and Cu) that could raise health and safety concerns were not in toxic concentrations in the samples. The seed flours were low in antinutritional factors (phytate, oxalate, tannin and trypsin) and processing (cooking and toasting) significantly reduced the levels of the antinutrients. The amino acid profile of the seed flours showed that aspartic acid (2.97-3.42g/100g) was the most concentrated amino acid followed by glutamic acid (2.80-3.31g/100g) and that leucine (1.65-1.93g/100g) was the most concentrated essential amino acid. The results of the physicochemical characteristics of the oils showed that the oils can be classified as drying oils with iodine values ranging from 146.27 to 186.25wijs. A high smoke point of about 250oC was obtained for the oils. The predominant fatty acid group in the oils was the polyunsaturated fatty acids with values ranging from 77.11 to 79.65%. Alpha-linolenic acid (61.96-62.64%) was found to be the most abundant fatty acid in the oils followed by linoleic acid (14.37-16.12%) and oleic (13.69-16.00%). Other fatty acids occurred in trace amounts. Campesterol and stigmasterol were the two most abundant of the sterols identified. Cholesterol was not detected in the oil obtained from the toasted conophor nut but its precursor, desmosterol was present. The serum lipid profile results showed that the parameters were within safe limits (<240mg/dl cholesterol; <200mg/dl triglyceride; ≥10mg/dl HDL-C and <160mg/dl LDL-C). Photomicrographs obtained from the histopathological assay revealed that organs from the animals fed on oil from cooked conophor maintained normal histology. Populations of Lactobacillus acidophilus and Lactobacillus plantarum as single or co-culture remained at > 6 log CFUg-1; this value suggests that conophor could be a potential probiotic food.