30B-24 |
Effect of soft rot severity (Erwinia carotovora ssp. carotovora) on quality characteristics of raw and cooked potatoes. |
F. NOURIAN1, A. C. Kushalappa2, and H. S. Ramaswamy1. (1) Dept. of Food Science & Agricultural Chemistry, McGill Univ., Macdonald Campus, 21111 Lakeshore Rd., Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada, (2) Dept. of Plant Science, McGill Univ., Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada Bacterial soft rot, caused by Erwinia carotovora ssp. carotovora (ECC), is a serious problem during storage of potatoes. High temperature, bruising, etc., increases respiration rate, which could be used as an indicator of tuber health. Diseases cause physical and chemical changes in potatoes, which affect consumers' acceptability. The objective of this study was to evaluate the effect of levels of disease severity on respiration rate and quality characteristics of raw and cooked potatoes. Potato tubers, cv. Chieftain, were surface sterilized, washed and air-dried. Seven wounds (5mm x 5mm) were made on each side of tuber, one side was inoculated with ECC and the other side was inoculated with water as a control. Inoculated tubers were exposed to 0, 12, 24, 36 and 48 h of mist at 20°C to produce five levels of disease severity. The volume of disease, texture and color were assessed, and the respiration rate was measured based on the amount of CO2 production. The volume of disease increased from 200 to 2700 mm3, and the respiration rate increased from 8.9 to 17.4 ml/kg.h as the disease progressed. Quality changes associated with progress of disease were: lowered firmness (18 to 11 N/mm2 in fresh and 6.6 to 2.6 N/mm2 in cooked potatoes), lowered L values and increased a and b values. Like wise ascorbic acid decreased from 3971 to 1794 mg/100g, reducing sugars increased from 6-8 mg/100g, total sugar increased from 12 to 15 mg/100g, total soluble solids increased from 2 to 2.2 °Brix, pH decreased from 6.06 to 5.89, and acidity increased from 0.05 to 0.1 %. The results showed that the longer the period of incubation, the higher the severity of disease, the lower the quality of tubers, and higher the respiration rate of tubers.
Session 30B, Fruit & Vegetable Products: Sensory, Product Development, Fresh-Cut, and Storage
|