SUMMARY— The effect of processing variables on the cell structure and physical characteristics of carrots were determined. The phloem portion of fresh carrots was subjected to one of the following treatments: blanching; cooking for 10 min; freezing at 0°F, −30°F or −320°F; freeze drying, compressing after freeze drying at approximately 1500 psi. Carrots at each treatment were tested for: (1) texture by means of the Ailo‐Kramer Shear Press; (2) water holding capacity by centrifuging at 500, 1000, 1500, 2000 and 2500 rpm; (3) histological changes by microscope observation of the tissue structure. Results indicate that among all treatments, freezing temperature is the most critical factor affecting the cell structure of the carrots. Freezing at 0°F or −30°F results in considerable disruption of the cellular structure, whereas it was minimal at −320°F. Carrots frozen at −320°F showed firmer texture as well as higher water holding capacity than the rest. Significant correlation coefficient was established between the shear press values and percent weight loss measured by centrifugation. This suggests that the latter may be used as an objective test for measuring textural changes in processed carrots and perhaps other foods.

No abstract

— A system for continuous microwave sterilization of foods packaged in plastic pouches has been designed, constructed and tested. Air pressure was used to prevent pouch rupture. Pouches containing food for use in military rations were sealed and introduced through an air lock on to a conveyor inside a plastic pipe within a microwave cavity. Microwave energy was supplied up to 10 kw at 2,450 MHz. Conveyor speed and power were regulated to provide the process time and temperature. Cooling was achieved in a cooling bath. Pouches were overpackaged in a foil laminate for additional protection. Several food products were processed. Total process times of 9–14 min were achieved.

The nonenzymatic discoloration of pureed foods (baby foods) has been the subject of many recent investigations. Livingston, Esselen, and Fellers (5) found that storage temperature and headspace oxygen were critical factors in the browning of apple sauce. These results were corroborated by Vilece (8) who carried out quantitative studies of the effect of oxygen and ascorbic acid on eight fruit and vegetable purees.I t was felt that additional information could be obtained by investigating more extensively the browning of one vegetable product. Green bean puree was selected because it was desired to determine the role of chlorophyll or its degradation products in browning. It was possible to remove all the colored constituents from green bean purke, and thus study browning without the masking effect or reactions of the natural pigments. End products of browning from stored green bean puree were isolated.

No abstract