Influence of diffused light seed storage and production location on physico-chemical characteristics and processing suitability of selected Kenyan potato (solanum tuberosum) varieties

Abstract

Potato varieties and different production sites can influence the quality of French fries and crisps. Planting well-sprouted potato seeds from diffused light storage (DLS) can lead to higher yields which can influence quality of tuber physico-chemical properties and hence the quality of processed French fries and crisps. The objective of the study was to determine the influence of diffused light seed potato storage (DLS) and production location on physico-chemical characteristics of Kenyan varieties ( Kenya Mpya, Dutch Robjin, Tigoni and Cangi) and their processing suitability into French fries and crisps. The study areas included National Potato Research Centre KARI-Tigoni in Kiambu County and three farmers (Pyhort, Kagema and Hellen) located in Nyandarua County in Kenya. DLS was achieved through farmers’ on-farm storage structures (ordinary wooden stores with iron-sheet roofs) exposing potato seeds to natural diffused light with good ventilation for 8 months. The study was carried out between April, 2013 and February, 2014. The selected tubers were processed into French fries and crisps then analyzed for sensory quality, moisture and oil contents as influenced by seed potato storage, varieties and production location. Completely randomized block design was used in the study where production locations were considered as blocks; independent factors were production locations, potato seed storage and potato varieties; dependent factors were soil pH, soil and potato tuber minerals contents, tubers specific gravity, dry matter content, vitamin C content, reducing sugars content, French fries and crisps moisture and oil contents and their sensory parameters. All the dependent analyses were performed following standard analytical methods. The data was analyzed using statistical analysis system (version 9). with production locations. Higher soil minerals contents led to higher potato tubers minerals contents except for Ca, Mn and Zn which showed reverse relationship. There were negative significant correlations between potato tubers dry matter content and soil pH and phosphorus; positive significant correlations between soil pH and potato tubers dry matter and vitamin C contents which showed that plant locality affected the quality of ware potatoes. Potato tubers’ specific gravity, dry matter, reducing sugars and vitamin C contents significantly (p≤0.05) differed with plant localities, potato varieties and seed potato storage. There were significant interactions among plant locality, variety and seed storage. DLS seed treatment caused production of potato tubers with higher specific gravity, dry matter content, vitamin C content, and minerals contents but with lower reducing sugars content. French fries and crisps processed from DLS seed had the required lower oil contents, moisture contents and higher levels of consumer acceptability in comparison with those from fresh seeds. All the sensory attributes of freshly processed French fries and crisps, differed significantly (p≤0.05) with plant localities, varieties and with seed potato storage. There were significant interactions among plant locality, variety and seed treatment. Diffused light seed potato storage and production location thus affect physico-chemical characteristics of Kenyan potato varieties and their processing suitability into French fries and crisps. Ministry of Agriculture, Livestock and Fisheries should ensure diffused light seed potato storage is adopted by more farmers in Nyandarua County and the rest of the Kenyan Counties so as to yield more and better quality ware potatoes for the potato industry.