EFFECT OF PRE-PROCESSING TECHNIQUES ON THE PHYSICOCHEMICAL COMPOSITION, ANTIOXIDANT AND FUNCTIONAL PROPERTIES OF BRAZIL NUT (Pachira glabra) FLOUR AND OIL

Abstract

Pachira glabra is one of the many underutilized oil plants in the tropics. The oil seed is commonly processed by boiling or roasting and consumed as snacks or hot drink for consumption. In this study, the mature seeds were processed into flour after pre-processing by germination and roasting. The flours were divided into two portions, a portion was defatted using n-hexane; the full fat, defatted flours and oil extracted from the same seeds were evaluated for physicochemical composition, antioxidant properties, functional properties and fatty acid composition. Germination consisted of soaking seeds previously for 4 h in water and sprouting for 4 days. Roasting was done in an open iron pan at a temperature of 75 - 85°C with continuous stirring for 10 min until the seed turned golden brown. The results showed that germinated defatted seeds flour had higher crude protein (19.51%) and crude fibre (11.22%) contents, when compared with the raw defatted seeds flour having 8.75% and 4.50% of crude protein and crude fibre, respectively. The roasting was able to reduce the phytate and oxalate contents by 45% and 18% respectively, while germination was able to reduce it by 40% and 12% respectively in full-fat samples. The anti-nutrient to nutrient molar ratios of the flours showed that the values were relatively low when compared to the critical values. The antioxidant properties of the full-fat flour showed that the roasting significantly (P>0.05) increased the level of phenolic content, flavonoid and DPPH contents by 82%, 58% and 21% respectively except for the ferric reducing antioxidant power content that shows no significant (P>0.05) difference based on preprocessing techniques used. The germinated defatted samples significantly increased the water and oil absorption capacities, swelling capacity, foaming capacity and bulk density of flour by 17%, 6%, 35%, 70% and 31% respectively. Defatting improved the water and oil absorption capacities, swelling capacity and foaming capacity of the flour. The study revealed that roasting increased the chemical properties of the pre-processed oil seeds, having the highest saponification value of 161.09 mg KOH/g. The fatty acids profile of the oil showed that the predominant fatty acids were oleic and linoleic which are unsaturated fatty acids, and are of health benefits to human. Germination increased the nutritional qualities while roasting significantly reduced the anti-nutrient properties. The flour and oil from the seeds may find use in the food industry.