J.A. Phillips

Microwave Blanching Of Vegetables For Frozen Storage

The quality of five vegetables, blanched using either microwave or hot water methods currently recommended to the American consumer, was examined after one, two, four, and six months of frozen storage. The vegetables were analyzed for residual peroxidase activity immediately after blanching. Storage stability of cooked and uncooked vegeta bles was determined by examining various quality factors after each period of frozen storage. Quality factors included color, texture, flavor, and overall acceptability of the vegetables as measured using objective methodology and sensory evaluation. Broccoli and zucchini retained high levels of peroxidase activity after microwave blanching. Broccoli and green beans blanched with microwave energy retained less chlorophyll (p 0.05), had higher shear force values (p 0.05), and received lower sensory eval uation scores than the water blanched vegetables (p 0.05) for quality factors common ly used by consumers. The texture of zucchini blanched with microwave energy was limp as measured by shear force and by sensory evaluation. No significant differences (p 0.05) were found in the quality of carrots or cauliflower blanched by the two meth ods. Instructions currently available for microwave blanching of vegetables for home freezing do not result in a quality product for all vegetables.

Home-Canned Tomatoes: A Comparison of the Effects of Varying Time and Temperature Combinations Durin Processing

Whole tomatoes were processed in pint and quart jars by home-canning, raw pack methods in a boiling-water bath or at pressures of 5, 10, or 15 p.s.i.g. (pounds per square inch as measured by gauge) to a minimum internal end-point temperature of 82°C (180°F). Thermocouples placed in the coldest point in the jars and attached to a recording potentiometer were used to establish the times for processing by the 3 pressure treatments. USDA recommended times were used for process ing in a boiling-water bath. The products from the four different treatments were analyzed and compared subjectively for color, flavor, texture, and acidity; and objectively for color, firmness, drained weight, acidity, and ascorbic acid content. Time and energy usage were also recorded and compared. No significant differences were found for any of the quality characteristics except color. However, the significant difference in color indicated by the sensory panel and an objective calcu lation from Hunterlab Color Difference Meter Measurements could not be attributed to processing treatments. There were differences in the amount of time involved and the kilowatt hours used in the canning procedures. Home-canning by any pressure method saved time and energy and yielded products comparable to those processed in a boiling-water bath.

Total And Active Time Required To Prepare Convenience And Home-Prepared Foods With An Electric Range And A Microwave Oven

Total and active time required to prepare 20 convenience foods and their home- prepared counterparts with a conventional electric range and a countertop mi crowave oven were measured. The majority of home-prepared foods (91%) re quired more total preparation time, and all home-prepared foods required more active preparation time, than did the convenience counterparts. Most foods pre pared with the electric range (78%) required more total preparation time than did foods prepared with the microwave oven. However the majority of microwave- prepared foods required more active preparation time or the same amount of active time as foods prepared with the electric range.

Cost of Preparing Convenience and Home-Prepared Foods With an Electric Range and a Microwave Oven

The composite cost of preparing 20 convenience foods and their home- prepared counterparts with an electric range and a microwave oven was deter mined. Per-serving costs were calculated for food, fuel used in preparation, and active preparation time at two wage levels. The majority of convenience foods (74%) cost more for food alone than did the home-prepared counterparts, while 52 percent of home-prepared foods cost more for fuel alone. Nearly all home- prepared foods (98%) had a higher cost for active preparation time at either wage level. When food and fuel costs were combined, 74 percent of convenience foods cost more than the home-prepared counterparts. However, when the cost of active preparation time was added, home-prepared foods become more expen sive. The combined cost for food, fuel, and active preparation time at minimum wage was greater for 70 percent of home-prepared foods than for convenience foods, and the combined cost with time valued at the market wage rate of a cook was greater for 91 percent of home-prepared foods.

Vitamin C Retention in Orange Juice Imitation Orange Juice, and Orange Beverage from Frozen Concentrates

The susceptibility of ascorbic acid to aerobic oxidation and possible loss of vitamin activity prompted a study to (1) determine if the vitamin C content of reconstituted frozen orange juice prepared using an electric blender is different from that prepared by stirring, and (2) to ascer tain the stability of vitamin C in reconstituted frozen orange concentrates (both pure and syn thetic) stored in a refrigerator for up to one week. Two cans of three brands of frozen concentrated orange juice and one brand of frozen con centrated orange beverage were reconstituted, one using an electric blender and the other by stirring. One can of imitation orange juice was reconstituted by stirring only. The beverages were analyzed immediately after reconstituting, after 3 days, and after 7 days of storage in a refrigerator at 0 ± 1°C (30°–34°F). Method of preparation did not have a significant effect on vitamin C (ascorbic acid plus dehydro-ascorbic acid) levels. Both time and product affected vitamin C levels. The syn thetically derived orange concentrates were higher in vitamin C (62 mg/100 ml) compared with the orange juices (52 mg/100 ml). All reconstituted concentrates studied were similar in retention of vitamin C, retaining 94 percent or more after 3 days and 91 percent or more after 7 days.