The effect of maturity, bruising, chemical treatment (CIPC) and Co2 levels in storage bins on respiration and Quality of processed potatoes(Solanum Tuberosum L.)

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Shamaila, Mawele M
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Two potato cultivars, ‘Norchip’ and ‘Russet Burbank’ were used to study the changes that occur in potato tubers during growing season and through storage. In addition, the post harvest effects of bruising, chemical treatment (CIPC) and CO2 build-up in storage bins on the quality of stored tubers were studied. The changes and quality parameters studied were respiratory rate (CO2 evolution), sucrose and reducing sugar levels, chip colour and dry matter content. It was found that the CO2 evolution increased to a value 8-14 hours after harvest and decline d to an equilibrium level after about 48-50 hours in both cultivars. The total amount of Co2 released by mature tubers was lower than that released by tubers harvested earlier in the growing season. Bruising of potato tubers was found to increase the respiration rates. Bruised tubers respired at higher rates intact tubers and the rate of respiration increased with the severity of bruising. Although the bruised immature tubers evolved more CO2 than mature tubers, the effects of bruised were more pronounced as the tubers matured. The sucrose content and reducing sugars of potatoes harvested early in the growing season were higher than those of tubers harvested late in the growing season. The chip colour in the cultivars remained relatively light and acceptable through the growing season while the dry matter content increased. In storage, the sucrose content continued to decline and the chip colour darkened with time. The reducing sugars drastically increased after sprout inhibitor treatment (CIPC) while the dry matter content did not change. Closure of storage bins and application of sprout inhibitor (CIPC) resulted in increased CO2levels in the storage bins, increased reducing sugars of tubers and dark chips (lower Agtron units). A new higher Co2 level was maintained in the storage bins even after regular ventilation was resumed. Bruising tubers at harvest resulted in increased sucrose content, dark chip and lower dry matter content both under short and long term storage. Bruised tubers showed blemishes and dark wounds at areas of impact and this contributed greatly to poor processed potatoes.