EFFECT OF STORAGE AND INSECT INFESTATION ON PHYSICO CHEMICAL AND NUTRITIVE VALUES OF SUN DRIED YAM ( DIOSCOREA ROTUNDATA )

Aremu , J . A . , Folarin , O . M . , Bamiro , F . O .

Department of Chemistry , University of Agriculture ,

P . M . B . 2240 , Abeokuta , Nigeria .

 

ABSTRACT

The effect of storage and insect infestation on the physico – chemical and nutritive values of infested and uninfested sun – dried yam ( Dioscorea Rotundata ) after storage for a long period under Nigerian household conditions were studied. The results obtained showed that the sample was non – resistant to insect infestation.The infested and uninfested samples were stored at ambient temperature and humidity under household condition.

The samples were subjected to proximate composition and mineral elemental analysis . Mineral elemental composition of both the infested and uninfested sun – dried yams were determined using Atomic Absorption Spectrometer model Bulks 210 VGP . There was no much difference exhibited for both infested and uninfested sun – dried yams for the elemental contents . Moisture content of the infested was found to be 10 . 96 % and the uninfested gave 8 . 75 % which indicated probability of further spoilage and further storage of the defeacation of the pest . Crude fibre content of the infested sample was 4 . 65 % and uninfested sample, 4 . 55 % . Value of ash obtained for the infested sun – dried yam sample was 4 . 24 % while that of the uninfested sample was 3 . 90 % . The infested yam gave a higher crude protein content of 11 . 47 % compared with 8 . 05 % uninfested sample . Oil content of the insect infested sample was found to be 1 . 28 % while that of the uninfested sample amounted to 0 . 98 % . A lower value of 71 . 05 % carbohydrate content was obtained for the infested yam compared with 78 . 55 % for the uninfested sample .

Generally , there was only significant decrease in carbohydrate values of the infested yam compared with the uninfested . The increase in protein value and moisture content could be due to the presence of the pest (insect ) present during crushing of yam samples into powder , which is always the practice by consumers before consumption .

 

KEY WORDS : DIOSCOREA ROTUNDATA, STORAGE, PROXIMATE ANALYSIS, MINERAL ANALYSIS.