Quality of and mold growth on white enriched bread for military rations following directional microwave treatment

Meals ready-to-eat (MRE) are self-contained and flexible packages used by military personnel while in the field to store food for an extended period of time; however, inclusion of white bread is not a common practice because of short shelf life stability and spoilage. The objective of this study was to determine mold inhibition and quality attributes over a 60-d period after applying directional microwaves. Different bread loaves were used for quality and for microbiological experiments. For microbiological analysis, bread was exposed to 0-, 5-, 6-, 7-, 8-, 9-, and 10-s directional microwave treatments after inoculation with a 3 strain cocktail of common bread mold, stored at 25°C for 60 d, and monitored for mold growth. For quality analysis, bread was exposed to 0- and 10-s treatments, stored at 25°C, and moisture, water activity (a_w), softness, and sensory analysis were analyzed on 0, 7, 14, 28, 45, and 60 d. There was no quantifiable mold present at day 0 when treated for 10 s (P < 0.05). By day 60, the 10-s treatment had significantly lower counts (< 3 CFU/g) than the remaining treatments. Directional microwave treatment significantly decreased the moisture content of the bread but was not detectable by consumers. There was no difference in a_w through day 45 but differences were detected at day 60. There were no differences in softness (mm) of the treated and untreated bread through day 60. No differences were detected by sensory analysis. Directional microwaves can be used to extend the shelf life of white enriched bread up 2 mo with minimal mold growth and without detrimental effect to quality.