Dados do Trabalho

Título

STORAGE OF APPLES IN MULTILAYER RESONANT CAVITY: EFFECT ON TEXTURE AND MICROBIOLOGICAL QUALITY

Introdução

Multilayer resonant cavities (MRCs), also called modified Faraday cages, comprising an inner conductive layer (usually galvanized steel) and alternating layers of dielectric and metallic materials, create a unique electromagnetic and electrostatic environment that retains energy as standing waves. This study investigates the potential of MRCs as a novel method for preserving the microbiological and texture quality of Gala apples during storage.

Material e Métodos

Fresh apples were randomly assigned to three storage treatments: inside MRC at room temperature (TA), control at room temperature (TB), and under refrigeration at 6°C (TC). Samples were stored for 54 days, with periodic collection (n= 6 apples) every 7-15 days for quantification of Mesophilic Aerobic Microorganisms (MA) and Yeasts & Molds (YM) populations using plate count technique (PCA and DRBC media, respectively). At the beginning and end of storage, the maximum resistance force (Fmax) and penetration of 2cm apple pulp and skin samples was determined using a texturometer, through compression and perforation tests, respectively. Data were subjected to ANOVA, followed by Tukey's test (p≤0.05).

Resultados e Discussão

Microbial populations remained approximately stable throughout storage in all treatments, with counts (logCFU/g) around 3.8 for YM and 4.1 for MA. No significant differences were observed among treatments at the latest analysis times. After 54 days, Fmax of pulp (133.7±9.4N) and skin (18.5±1.6N) of apples from TA were significantly higher than TB and comparable to TC.

Conclusão

These results suggest that MRC storage can maintain apple texture as effectively as refrigeration, without requiring energy input. This may be attributed to the unique electromagnetic and electrostatic environment generated by the cavity, which may immobilize water and reduce the effective energy available to initiate degradative reactions by electrostatic discharge of air at the conductive inner layer, thereby lowering their rate. Although MRC storage did not result in microbial reduction, population growth was also not favored, similar to what occurred under refrigeration. The findings highlight the potential of MRCs as a sustainable and cost-effective method for preserving fresh produce quality. Further research is needed to elucidate the underlying mechanisms and assess effects on other fruit quality parameters, such as physicochemical and biochemical attributes, over extended storage periods.