Cassava chips quality as influenced by cultivar, blanching time and slice thickness
Cassava forms part of diets in Kenya with both the roots and leaves being consumed as food. The short shelf-life of 72 hours and cyanogenic glucosides limit the extent of utilization. Currently, fried cassava chips and crisps are increasingly being consumed as snacks; and fried cassava chips are produced by street processors. The quality and safety of these products is not known, therefore, the current study was to establish the influence of cassava cultivar, blanching time and slice thickness on quality of fried cassava chips. Moisture, vitamin C and cyanide content in the raw cassava cultivars were determined before processing. The three raw cassava cultivars coded as MH95/0183, MM96/2480 and Fumba chai were washed, peeled and sliced into thickness of 6 mm, 10 mm and 20 mm. Equal groups of the slices were blanched at 950C for 0 minutes, 5 minutes and 10 minutes each and then subjected to frying temperature of 1700C. The physico-chemical and sensory properties of fried cassava chips were determined. Dry matter content, vitamin C content and cyanide levels significantly (p < 0.05) differed among the three raw cultivars except in MH95/0183 and MM96/2480. A strong positive relationship (r = 0.98) existed between moisture and cyanide contents in the raw cultivars. Mean cyanide levels in the three roots was: 37.04 mg/kg, 16.37 mg/kg and 48.48 mg/kg in MH95/0183, MM96/2480 and Fumba chai, respectively. Dry matter content was 36.79 %, 37.69 % and 30.42 % in MH95/0183, MM96/2480 and Fumba chai. The physico-chemical and sensory properties significantly (p < 0.05) differed within and across the cultivars as affected by processing conditions. Mean cyanide range was 1.4 - 11 mg/kg, oil content ranged 3.78 - 18.48 % and vitamin C content ranged 7.59 - 50.48 mg/100 g. Significant (p < 0.05) relationship (r = 0.707) existed between slice thickness and the redness color parameter. Cultivar, slice thickness and blanching time form important yardsticks in processing fried cassava chips. Proper choice of these parameters is, therefore, important in processing quality and safe cassava fries. Slice thickness of 6 mm combined with long blanching time of 10 minutes result in fried cassava chips with low and acceptable cyanide content as well as satisfactory consumer preference based on color, texture, oiliness and overall acceptability.
Key words: cyanide, quality, cassava, slice thickness, cultivar, blanching, consumer preference