). Effects of Different Processing Methods on Nutrient and Anti-Nutrient Compositions of African Star Apple (Chrysophyllum albidum) Kernels

Abstract

Effect of different processing methods on nutrients and anti- nutrient compositions of African star apple (Chrysophyllum albidum) kernels were investigated. Raw African star apple kernels were collected for the study. Four different processing methods (boiling, fermentation, soaking and roasting) were carried out. All the processed kernels were milled and taken to the laboratory for proximate, amino acids, minerals, vitamins and phytochemical analyses. Results of the study show that raw African star apple kernel contains 93.21 %dry matter, 12.03 % crude protein, 7.10 % crude fibre, 1.45 %ether extract, 1.85 %ash and 70.78 % nitrogen free extract and very high in gross energy (4000.10 Kcal/kg). Processing significantly reduced (P<0.05) crude protein in all the methods except boiling (13.26 %). Boiling and roasting significantly increased the energy content of the kernels. All the processing methods significantly (P<0.05) increased the contents of all the amino acids analyzed except leucine and lysine. Boiling, fermenting and soaking significantly (P<0.05) reduced the contents of leucine and lysine. Also, processing significantly affected the mineral contents of the African star apple kernels (P<0.05). All the processing methods except soaking reduced iron content in the kernel. The phosphorus content of the kernel (2.98-3.09 mg/100g) was not significantly affected by any of the processing methods. The results of the vitamin composition showed that only thiamine, riboflavin and ascorbic acid were significantly influenced (P<0.05) by the different processing methods. The other vitamins (retinol, cholecalciferol, α-tocopherol and menadione) were not significantly affected by any of the processing methods. Raw kernel was found to contain anti nutritional factors such as saponin (5.00 mg/100g), tannin (7.33 mg/100g), oxalate (12.41 mg/100g) and phytate (10.06 mg/100g). Anti-nutritional factors were significantly reduced (P<0.05) by the processing methods although boiling gave the highest percentage reduction of anti- nutritional factors (saponin, 93.40 %, tannin, 91.68 %, oxalate, 87.51 % and phytate, 98.31 %). It was concluded that African star apple kernel should be processed through boiling before being used as livestock feed.