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Effect of Blanching, Refrigeration and Freezing on Ascorbic Acid Retention in Some Selected Vegetables

M. Burhan Uddin
Department of Food Technology & Rural Industries, Banqladesh Agricultural University, Mymensingh.

J. U. Chowdhury
Department of Food Technology & Rural Industries, Banqladesh Agricultural University, Mymensingh.

Abstract/ Executive Summary:

A study was undertaken to evaluate the losses of ascorbic acid of Cabbage, Peas and Indian spinach when steam blanched and hot water blanched with storage in refrigeration (7⁰C) and freezing (- 20⁰C). Adequate water blanching and steam blanching (at zero pressure) periods for these vegetables were determined using catalase and per oxidase tests as index of enzyme inactivation and these were three minutes and five minutes respectively. The reduction in ascorbic acid in samples of the stored vegetables were recorded at an interval of 7 days up to 28 days. Ascorbic acid was better retained in steam blanched vegetables than in unblanched and hot water blanched ones. Its loss was insignificant in peas and significant in cabbage and indian spinach after two weeks of storage in refrigerator at 7⁰C. But these vegetables could be preserved for more than two weeks in freezing storage (- 20⁰C) with retention of significant amount of ascorbic acid.

Keywords: Blanching, Refrigeration, Freezing, Ascorbic acid retention, Cabbage, Peas and Indian spinach

Location: Department of Food Technoiogy and Rural Industries, BAU, Mymensigh

Start Date:

End Date:

Program Area: Postharvest and Agro-processing

Commodity: Vegetables

Objectives:

To evaluate the losses of ascorbic acid of Cabbage, Peas and Indian spinach when steam blanched and hot water blanched with storage in refrigeration (7⁰C ) and freezing ( - 20⁰C).

Methodology:

The samples were analyzed separately for the ascorbic acid content of each by visual titration method using 2,6 dichlorophonel indophenol dye solutlon. Adequate steam blanching (at 0 pressure) and water blanching (boiling water) time was determined for these vegetables using catalase and peroxidase tests. The period of steam blanching and water blanching were three and five minutes respectively for each vegetables. Each of the prepared vegetable (shreds of cabbage, pods of peas and pieces of indian spinach) was then devided into three lots - one for water blanching, one for steam blanching and the other for preserving as fresh or unblanched state. Immediately after blanching the ascorbic acid content of the steam and water blanched vegetables were determined by the visual titration method. The blanched and unblanched vegetables were then preserved in refrigeration (at 7⁰C) and freezing (at - 20⁰C} chambers in unit packages (each polvethylene bags containing about 100 gms vegetables). At an interval of seven days the ascorbic acid content of the unblanched and blanched vegetables were determined by aforesaid method. The experiments were continued for four weeks

Source of Information: Bangladesh J. Agril. Sci. 15 (2) : 299-302 ; 1988

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Losses was insignificant in peas and significant in cabbage and indian spinach after two weeks of storage in refrigerator at 7 ⁰C. But these vegetables could be preserved for more than two weeks in freezing storage (- 20⁰C) with retention of significant amount of ascorbic acid.

Knowledge Management: Journal