Biodiversity of potato cultivars as related to nutrient content and quality

Abstract

Biodiversity is essential to human nutrition and food security as it can ensure stable and sustainable food production and contribute to a diverse diet. Biodiversity is classified as the degree of variation within a species. The higher the degree of variation within a species the stronger the species and the greater the chance of species survival. More than 4 000 different potato cultivars are cultivated worldwide making potatoes a highly biodiverse crop that can be easily grown under a variety of agronomical conditions particularly in many developing countries to contribute towards human nutrition, agriculture and economics. More than 80 different cultivars are produced in South Africa and it is possible that there may be a significant difference in the nutritional value of these different cultivars. The purpose of this study was to investigate the effect of cultivar on macronutrient and mineral content (with and without the skin) and culinary applications of the 11 most commonly consumed potato cultivars in South Africa. Nutrient analysis was conducted on tubers with and without the skin. The potatoes were boiled, baked, microwaved and deep fat fried prior to objective and sensory analysis. A market investigation was conducted to develop a repeatable cooking method for the traditional South African deep fat fried “slap chips” that mimics market conditions. Focus groups were used to develop new descriptive words for labelling purposes that describe the best preparation techniques for cultivars with different intrinsic qualities. It was found that there is a significant difference in the macronutrient and mineral values of different potato cultivars irrespective if analysed with or without the skin. This confirms the variation of nutrient delivery within the species Solanum tuberosum as currently available on the South African market. It was found that when using less invasive cooking methods such as boiling, baking and microwaving cultivar characteristics remain the predominant determining factor influencing textural characteristics. Dry matter and starch proved to be the objective measures that best described the variance in data. By means of a descriptive sensory panel it was found that there is no clear pattern of differences amongst the types of cultivars (waxy, waxy/floury, floury) for any of the sensory attributes evaluated with a more invasive culinary application such as deep fat frying. It can therefore be assumed that all the cultivars will be suitable for preparation in this manner. Potatoes are a highly biodiverse, nutrient dense crop that can be promoted for their contribution to a diverse diet. As potatoes can be cultivated in a wide variety of agronomical conditions they can form part of a nutrient sensitive agricultural approach to alleviate global malnutrition and contribute to dietary diversity. Further investigation into the contribution of particular cultivars in this regard is recommended.