Assessment of over time changes of moisture, cyanide and selected nutrients of stored dry leaves from cassava (Manihot esculenta Crantz)

Abstract

Most fresh agricultural products are quickly perishable and various methods of preservation are necessary. Cassava leaves from different types of cassava (bitter, sweet and wild) were (1) dried un-pounded and (2) dried pounded in a tunnel solar dryer, filled in high density polyethylene material, sealed and placed into opaque cartons. The packing materials were purposively chosen to limit water, oxygen and light access. The complete drying was when samples were completely brittle. The storage was done at room temperature at Sokoine University of Agriculture, Morogoro, Tanzania. The main purpose of the study was to estimate shelf life by evaluating satisfactory quality in terms of nutritional values, dryness and organoleptic parameters. Water, cyanide, ascorbic acid, β-carotene, protein, iron, phosphorus, potassium and zinc were chemically analyzed at zero, three, six, nine and twelve months of storage. Dryness and organoleptic parameters were also evaluated at these different storage lengths. Processing procedure had significant effect only on water (p=0.0358), cyanide (p=0.0189) and β-carotene (p=0.0214) contents. Storage time affected water, cyanide, ascorbic acid, β-carotene, protein, iron, phosphorus, potassium and zinc significantly (p<.0001). Water content increased by 6.8% and ascorbic acid decreased to zero while β-carotene, protein, minerals and cyanide showed slight decline during the storage period. The optimum storage time under the conditions was judged to be six months for nutrients and organoleptic parameters stability.

Keywords: Cassava leaves, solar drying, storage time, Rwanda.

African Journal of Biotechnology, Vol 13(42) 4112-4118