Quality of and Mold Growth on White Enriched Bread for Military Rations Following Directional Microwave Treatment

Abstract

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 degrees C for 60 d, and monitored for mold growth. For quality analysis, bread was exposed to 0- and 10-s treatments, stored at 25 degrees 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.

Analysis of bread dielectric properties using mixture equations

“…Thus methods to control microbial spoilage are of great importance to the bakery industry (Smith et al, 2004). Microwave (MW) and radio frequency (RF) heating have been studied as a means to control mold growth and extend shelf life of finished bakery products (Cathcart et al, 1947;Bartholomew et al, 1947;Olsen, 1965;Zhao et al, 1999;Piyasena et al, 2003;Tang et al, 2005;Lakins et al, 2008). In order to obtain desired heating performance in microwave and RF heating treatment, relevant properties of foods must be obtained, among which dielectric properties are the most important.…”

Analysis of bread loss factor using modified Debye equations

“…New mold control methods that do not rely on chemical preservatives are of great interest to the bakery industry. Post-baking treatments of packaged bakery products using microwave (MW) and radio frequency (RF) energy hold good potential (Zhao et al, 1999;Piyasena et al, 2003;Koral, 2004;Lakins et al, 2008). In order to design effective MW or RF treatments that provide a good balance between mold control and retention of product quality, it is desirable to gain a better understanding of the dielectric properties of bread products.…”

Dielectric properties of microwave-baked cake and its constituents over a frequency range of 0.915–2.450GHz

“…Thus methods to control microbial spoilage are of great importance to the bakery industry. Microwave (MW) heating has been studied as a means to control mold growth and extend shelf life of finished bakery products (Tang et al, 2005;Lakins et al, 2008). The application of microwave heating is of particular interest because of the operational efficiencies it affords.…”