EFFECT OF STEAM AND HOT‐WATER BLANCHING ON ASCORBIC ACID CONTENT OF SNAP BEANS AND CAULIFLOWER¹

Abstract

The fact that vegetables which are to be preserved by quick freezing and freezer-locker storage should be subjected to a preliminary blanching or scalding process is generally recognized. This study was undertaken in order to compare the effects of hot-water and steam blanching as practiced in the home on the ascorbic acid content of snap beans and cauliflower. Determinations of ascorbic acid content were made during the preparation for freezing, after quick freezing, and at intervals during freezer-locker storage.Few studies have been published comparing hot-water and steam methods of blanching. Brown (1941) stated that hot water is a more effective blanching agent than steam because it separates the particles, reaches all surfaces, and has a high thermal capacity. He added that steam should be used for blanching vegetables that have extremely large surfaces exposed to leaching action. The effect of blanching prior to canning of fresh peas, broad beans, stringless and runner beans, carrots, potatoes, parsnips, sprouts, swedes, dried pea, and dried beans has been studied by Adam and Horner (1941). They reported the average retentions of ascorbic acid in all the vegetables tested as 72, 64, and 58 per cent for the one-, three-, and six-minute water blanch, respectively, and 75 per cent for the material blanched in steam for three minutes. Melnick, Hochberg, and Oser (1944) concluded that steam blanching is to be preferred for snap beans since the hot-water method resulted in a notable loss of soluble nutrients while the loss during steam blanching was not significant. Farrell and Fellers (1942) found that 33 per cent of the total ascorbic acid content of Bountiful snap beans was lost during preparation of the beans for freezer storage.No pertinent data have been found concerning the effect of blanching on the ascorbic acid content of cauliflower. EXPERIMENTAL PROCEDUREThe Stringless Black Valentine snap beans used in this study were grown under the supervision of the Department of Horticulture. Series of plantings were made in both 1942 and 1943 so that the snap beans This paper results from a study which was carried on for two years, 1942 and 1943. The data obtained in 1042 represent a portion of the thesis submitted by Janet L. Retzer to the Graduate School of the University of Illinois in partial fulfillment for the degree of Master of Bcienee.

Effects of Freeze Preservation on Nutrients

“…Cumulative losses (after completion of freezing) of vitamin C from vegetables during storage at -18°C (means plus ranges). References: Asparagus [Gordon and Noble 1959 ;Guerrant 1957 ;Jenkins et al 1940 (reduced ascorbic acid plus dehydroascorbic acid)]; green beans Dietrich et al 1959;Pierce et al 1955;Retzer et al 1945); broccoli (Fisher and Van Duyne 1952;Gordon and Noble 1959;Guerrant 1957); cauliflower [Gordon and Noble 1959;Guerrant 1957;Jenkins et al 1940 (reduced ascorbic acid plus dehydroascorbic acid) ; Retzer et al 1945] ; green peas (Bedford and Hard 1950;Derse and Teply 1958;Guerrant and O'Hara 1953;Guerrant et al 1953;Volz et al 1949;Weits et al 1970); spinach (Bedford and Hard 1950;Dietrich et al 1960;Fisher and Van Duyne 1952;Guerrant 1957;Juries 1970;Tinklin and Filinger 1956;Volz et al 1949;Weits et al 1970).…”

“…Unfortunately, only a few studies have dealt with this question and the results are contradictory (Fisher and Van Duyne 1952;Retzer et at. 1945).…”

“…g Gordon and Noble (1959), Noble and Gordon (1964), Retzer et al (1945). h Barnes and Tressler (1943), Batchelder et al (1947), Bedford and Hard (1950), Feaster et al (1949), Guerrant and O'Hara (1953), Guerrant etal.…”

Effect of Duration and Temperature of Blanch on Vitamin Retention by Certain Vegetables

“…Retzer, Van Duyne, Chase, and Simpson (9) studied the effect of steam and hot-water blanching on the ascorbic acid content of snap beans and cauliflower. Snap beans were found to lose 15% of the vitamin during water blanching and 11% during steam blanching.…”