Processing traits of potato varieties grown in Uganda for potential production of French fries

Abstract

In Uganda, annual potato production is estimated at 162,151 metric tons which puts the country in a strategic position to benefit from the regional growing demand for processed potato products such as French fries. However, lack of sufficient data on the commonly grown potato varieties to support industrial-level processing, and inadequate knowledge on effects of processing treatments on the quality of the processed products are among the major challenges facing the Ugandan potato value chain. This study screened the major potato varieties grown in Uganda for their processing qualities. The quality attributes considered were physical characteristics of tubers (size, shape, eye depth, skin and flesh colour) and chemical composition (dry matter, starch, reducing sugars, amino acids). Analysis of variance was performed to assess the effect of processing methods on the performance of the most suitable varieties for processing into French fries. The varieties studied were Cruza, Kachpot1, Kimuli, Kinigi, Mbumbamagara, Rutuku, Rwashaki, Rwangume and Victoria. Consumer acceptability tests for the French fries were done five minutes after frying. The study findings indicated that Kinigi had the highest dry matter content (27.2%) whereas Rutuku had the lowest (19.28 %). Most varieties had tubers of medium size (50-60 mm), are round in shape with medium eye depth and had moderate levels of reducing sugars with the highest recorded being 0.55g/100g fresh weight basis (FW) in Kimuli, whereas Kinigi had the lowest level of 0.02g/100g FW. Kachpot1, Kinigi and Rwangume were the most suitable varieties for French fries processing because of their highest starch content (≥20%) and low concentration of reducing sugars (less than 0.50g/100g FW), tuber size (59.74 mm), round shape and medium eye depth (0.29 mm). Results confirmed that genotype significantly affected the quality of final product, with Kachpot1, Kinigi and Rwangume being the appropriate genotypes for French fries processing. In addition, processing methods significantly influenced the moisture content, oil uptake during processing, acrylamide concentration, colour and overall acceptability of the French fries. Potato strips of 12 mm x12 mm blanched at 85oC for 5 minutes yielded the best results for all the quality attributes. Given the suitability of Kachpot1, Kinigi and Rwangume for processing French fries and the increasing demand for the product, there is need to popularize and promote these varieties among farmers in order to produce adequate volumes industry-level processing requires. Further research should be done on the suitability of the other six potato varieties for production of other high value products such as flour, crisps, mashed potato among others.