CAROTENE AND ASCORBIC ACID CONTENT OP FRESH MARKET AND COMMERCIALLY FROZEN FRUITS AND VEGETABLES¹

Abstract

The present status of our knowledge of the stability of vitamins -2 and C in fruits and vegetables when subjected to varied conditions of storage and freezing are given here in the form of a review of investigations and original data. It is hoped that the facts presented will give a clearer conception of the effect of certain environmental factors on the vitamins. Frozen fruits and vegetables are becoming more and more widely consumed and form an important addition to the human dietary. Retention of the vitamins in these processed foods is of the greatest health interest.Until recently it has been impossible to evaluate exactly the vitamin values of foods obtainable on the market because the standard tests using the biological or animal-survey methods could not always detect variations such as are caused by maturity, variety, locality, or temperature of exposure.With the discovery by Tillmans, I-Iirsch, and IIirsch (1932) of the rapid chemical method of determining vitamin C and its rapid development and improvement by many laboratories, investigations on the effect of environmental conditions, such as storage, processing, and cooking, have been greatly stimulated. Similarly, recent development of spectrophotometric and chemical methods for the determination of vitamin A and carotene has led to a renewed interest in the vitamin A content of foods and the effect of various factors involved in food distribution and preparation of this vitamin. Vitamin A, however, has been far less concerned in food research during the past few years than vitamin C. Reviews of quantitative data on the occurrence of vitamins in fresh and processed foods have been published by Fellers (1936) and by Daniel and Munsell (1937). Because of the newness of suceessful freezing methods, relatively fewer investigations have been conducted on the effect of freezing than on the various heat treatments.

ASCORBIC ACID, THIAMIN, RIBOFLAVIN, AND CAROTENE CONTENTS OF ASPARAGUS AND SPINACH IN THE FRESH, STORED, AND FROZEN STATES, BOTH BEFORE AND AFTER COOKING 1,2

“…They also found that spinach grown in muck soil contained 50 per cent less ascorbic acid than did the same variety grown on upland soil, and that the autumn spinach contained nearly a third more ascorbic acid than did spring spinach. Similarly, Feener, Palmer, and Fitzgerald (1937) and Fitzgerald and Fellers (1938) noted that the ascorbic acid content of spinach varied with the season of growth.…”

“…Olliver (1936) found that asparagus tips lost 80 per cent of their ascorbic acid during four days' storage a t room temperature. Fitzgerald and Fellers (1938) noted a 20-per cent loss of ascorbic acid from asparagus stored at 21.1°C.(70"F.) for 24 hours.…”

“…They also reported that broken spinach leaves often contained 60 per cent less ascorbic acid than did whole leaves. Fitzgerald and Fellers (1938) found that spinach lost 43 per cent ascorbic acid when stored a t 21.l0C.(70"F.) for 24 hours, and 47 per cent when thus stored for 48 hours.…”

“…E f e c t of Freezing Procedures: Fitzgerald and Fellers (1938) gave the ascorbic acid content of quick-frozen asparagus as from 9 to 32 mg. per 100 gm. ; of fresh cut asparagus, not of the same lots, as from 18 to 44 mg. per 100 gm.…”

L’influence de l’hydratation sur les pertes de vitamine C dans les laitues

“…A côté du «facteur temps», le facteur «tem pérature» est capital pour la conservation de la vitam ine C: Fitzgerald (6) Lors d'une mission de l'un de nous à Bagdad, notre collaborateur Izmirlian, directeur de l'Institut National de N utrition, découvre la teneur exceptionnellement élevée en acide ascorbique, d'un végétal poussant à l'état sauvage: le Khoubbaz (10). Or, si la perte vitam i nique est extrêm em ent rapide dans le Khoubbaz conservé à sec (de 117,5 mg. pour 100 g., à 23,3 mg. pour 100 g. au quatrièm e jour), la conservation en est nettem ent améliorée si la plante a la racine m ain tenue dans l'eau: (111,5 mg. pour 100 g. au quatrièm e jour), c'est à dire un taux pratiquem ent inchangé.…”