The enhancement of the nutritive value of mango seed kernels for poultry by thermal treatment and radiation processing

Abstract

Raw seed kernels of local mango varieties (Magnifera indica L.) were analyzed for composition, levels of trypsin inhibitors, tannins, cyanogenetic glucosides, in vitro protein digestibility and apparent metabolizable energy (AMEN) as being effected by boiling, autoclaving as well as irradiation at 5, 10, 15, and 20 kGy. The air‐dry mango seed kernels (MSK) contained CP 70 gkg‐1, EE 128gkg‐1, and tannins 67 gkg‐1. Compared with raw kernels the contents of trypsin inhibitory activity (30 TIU g‐1) and cyanogenetic glucosides, measured as hydrocyanic acid (71 mgkg‐1), were lowered by boiling, autoclaving and radiation treatments. Tannin content (67.2 gkg‐1 in raw kernels) was decreased only by boiling or autoclaving, but irradiation did not introduce any effect. The low in vitro protein digestibility and AMEN values of raw MSK were enhanced by processing. The improvements were paralleled to reductions in trypsin inhibitory activity, cyanogenetic glucosides and tannin contents. Greater improvements were noticed with boiling and autoclaving than with irradiation alone. Autoclaving for 30 min plus irradiation treatment up to 20 kGy increased the in vitro protein digestibility and AMEN by 139% and 72%, respectively. These results indicate that tannins, trypsin inhibitors and cyanogenetic glucosides are responsible for the poor nutritive value of MSK. The effects of feeding 200 g kg‐1 raw or processed MSK on the performance of broiler chicks were examined. The inclusion of raw kernel affected body weight gain and feed consumption, while weight gain of birds fed the autoclaved (30 min) plus irradiated (20kGy) kernels was significantly more improved than by the other treatments. However, feed conversion ratio was not significantly different between groups fed the processed MSK, The results showed that the combination of autoclaving for 30 min plus irradiation up to 20 kGy upgraded the nutritive value more than the other tested treatments and that this method is most effective in processing MSK to be used as animal feed.