Analysis of four seeds used as soup thickeners in the South Eastern part of Nigeria

Abstract

Food safety is a primary concern for everyone, especially in our country Nigeria where it forms part of the government 7-point agenda. Some seeds used as soup thickeners include Afzelia africana, Brachystogia nigerica, Mucuna sloanei and Detarium microcarpum. The analysis of the proximate composition of the four selected seeds revealed that there were predominantly made up of carbohydrate (ranging from 86.27±0.80% in Afzelia africana to 96.12±0.60% in Detarium microcarpum) and were very low in moisture, protein, fiber, and ash. Analysis of the vitamin contents showed that the seeds were high in water-soluble vitamins. Investigation into the vegetable oil properties extracted from the four seeds showed that Afzelia africana has the highest oil content of 18.50% while Mucuna sloanei, Brachystogia nigerica and Deutarium microcarpum have 6.25%, 7.91% and 7.41% respectively. Afzelia africana also has the highest value of total fatty matter (98.47%) of all the samples. Deutarium microcarpum has moisture content of 5.80%, Brachystogia nigerica 4.30%, Mucuna sloanei 4.07% and Afzelia africana 2.80%. The acid value ranged from 0.20 for Deutarium microcarpum to 4.90 mgKOH/g for Mucuna sloanei. The free fatty acid content ranged from 2.60 for Afzelia africana to 14.00% in Brachystogia nigerica. The saponification value of Afzelia africana, Mucuna sloanei, Brachystogia nigerica and Detarium microcarpum were 229.12, 182.00, 162.90 and 123.3mgKOH/g respectively while the iodine values were found to be less than 100. Afzelia africana contained 41.25% linoleic acid, 33.65% palmitic acid, 12.65% oleic acid, 6.97% stearic acid, 1.54% myristic acid and trace amount of lauric acid 0.69%. Mucuna sloanei was found to be composed of 67.12% palmitic acid, 6.19% myristic acid and 4.71% myristoleic acid. The fatty acid profile of Brachystogia nigerica revealed 52.36% palmitic acid, 18.09% oleic acid, 14.12% stearic acid, 4.08% myristic acid and 1.46% lauric acid. Detarium microcarpum contained 6.86% myristoleic acid, 5.87% myristic acid and 2.28% linolenic acid. Afzelia africana had the highest iodine value of 74.10 while Mucuna sloanei, Brachystogia nigerica and Detarium microcarpum had 6.79, 25.70 and 55.00 (Wij's) respectively. The amino acid profile showed that they contained a reasonable amount of essential amino acids in g/100g protein such as of lysine (3.02–7.90), histidine (2.18–4.5), of threonine 1.13–2.04), valine (1.82–3.37), methionine (1.11–7.82), leucine (3.77–6.23), isoleucine (1.62–2.57), phenylalanine (1.88–4.67) and arginine (3.37–9.30). This supports that the seeds can supply essential nutrients such as amino acids and essential fatty acids, (especially for Afzelia africana and Deutarium microcrpum) that the body cannot synthesize, but must be supplied exogenously. It showed also that it can maintain the protein/nitrogen balance in the body. The high carbohydrate content also showed its essence in nutrition, especially as thickeners while the vitamin contents supports their importance as part of a meal.