44C-10 |
Changes in a-amylase activity, starch and sugars in jicama roots stored at chilling conditions |
E. MERCADO-SILVA and B. Lazo-Mendoza. Departamento de Investigación y Posgrado en Alimentos, Universidad Autónoma de Querétaro, Centro Universitario, Cerro de las Campanas s/n, Querétaro, Qro., 76010, Mexico The jicama root is appreciated as fresh vegetable and it is used like substitute of the water chest nut in the Chinese cuisine, but their storage under refrigeration is limited due of their sensitivity to chilling injury. There are possibilities that the chilling temperatures induces sweetening of the root and decrease their quality. The objective was to study the changes in the starch content, sugars and a amylase activity in jicama roots stored at 10 and 20°C. 72 roots were stored at 10 and 20°C during 20 days and each four days were taken three roots for inmediate analysis and others three were transferred at 20°C for four days and finally analyzed for starch content by enzymatic method, sugar content byspectrophotometric method and a amylase activity of the flesh using a starch solution as substrate and iodine solution for color development after 10 minutes reaction time. The recovered starch amount after 20 days of storage was lower than the starch content at time zero days (3.3 g/100 Fresh weight). Roots stored at 10°C and the transferred to 20°C for four days showed the lowest content (1.7 and 1.6 g/100g FW respectively). The sugar content increased in the roots stored at chilling conditions and also for the samples transferred from 10 to 20°C reaching concentrations of 3.4 g/100g FW. The samples maintained at 20°C had 2.6 g/ 100g FW. The a- amylase activity was higher in the samples maintained at 10°C and transferred at 20°C. However the control group (20°C) was similar at samples maintained at 10°C. These results indicate that the jicama root present the sweetening phenomena as a symptom of chilling injury and this aspect decreased their quality.
Session 44C, Fruit & Vegetable Products: Chemistry
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