Minimal processing of a Granny Smith apple puree by microwave heating

Consumers are demanding more fresh appearing, more convenient and healthier fruit products. At the same time fruit industries look for technologies to decontaminate fruit products by minimising losses of nutritional and sensorial quality. Microwave heating technology gives the opportunity to have a fast heat process in a continuous mode. Granny Smith apple puree, with natural additives, was prepared and submitted to a) short microwave treatment during 35 s at 652 W. The effects of the treatment were evaluated looking for, the stability of vitamin C, total polyphenol content, as well as viscosity, colour and titratable acidity over a period of two weeks. Its effect on E. coli, L. innocua and indigenous microbiota was evaluated. Results showed that while a reduction of microorganisms was achieved, the treatment could not inactivate the enzymes present in the product and prevent vitamin C degradation. On the other hand the treatment did not affect the stability of the viscosity and titratable acidity during storage period. Industrial relevance: A minimal industrial process of apple products that reduces pathogenic microorganisms, while maintaining nutritional and sensorial attributes is needed to increase the competitiveness of the fruit sector. Short microwave treatment may be a solution to achieve this objective. (C) 2009 Elsevier Ltd. All rights reserved.