Physico-chemical properties of selected Irish potato varieties grown in Kenya

Abstract

Potatoes have attracted great interest as a feasible solution to food insecurity and climate change in Kenya. Many varieties have been developed but their nutritional value and suitability for domestic and industrial use are not sufficiently studied. A comparative study of physical attributes (tuber weight, size, shape, eye depth and number, specific gravity, colour) and nutrient composition (proximate, minerals, vitamins, and simple sugars) of three varieties (Unica, Shangi and Dutch robjin) were evaluated using standard methods. Shangi and Unica had lengths above 50 mm recommended for French fry processing, but had deep eyes (1.54-2.98 mm). Unica had a red skin colour while Shangi was yellow. Both varieties had yellow coloured flesh. The specific gravity of the varieties ranged from 1.08-1.12. Shangi and Unica were suitable for processing based on their physical attributes except for eye-depths. Dutch robjin had the highest content of protein (1.76%), carbohydrates (20.43%), total ash (1.10%), crude fibre (1.11%), iron (0.87 mg/100 g), thiamine (0.036 mg/100 g), niacin (0.93 mg/100 g), pyridoxine (1.92 mg/100 g) and folic acid (34.62 µg/100 g). Unica had the highest zinc (0.41 mg/100 g) and calcium (8.51 mg/100 g) contents. Reducing sugar content across the three varieties was within recommended range for processing (97.75-107.53 mg/100 g). There was a significant (p<0.05) varietal difference in most of the nutrient components. Dutch Robjin showed the best nutritional quality.   Key words: Potato quality, Solanum tuberosum L., physical characteristics, nutrient content, food composition.