Effects of Microwave Heating on Sensory Characteristics of Kiwifruit Puree

The effect of microwave processing on the characteristics of kiwifruit puree was evaluated by applying various gentle treatments. Different combinations of microwave power/processing time were applied, with power among 200-1,000 W and time among 60-340 s, and various sensory and instrumental measurements were performed with the aim of establishing correlations and determining which instrumental parameters were the most appropriate to control the quality of kiwi puree. The water and soluble solids of the product, 83 and 14/100 g sample, respectively, did not change due to treatments. For sensory assessment, an expert panel was previously trained to describe the product. Fourteen descriptors were defined, but only the descriptors 'typical kiwifruit colour', 'tone', 'lightness', 'visual consistency' and 'typical taste' were significant to distinguish between kiwifruit puree samples. The instrumental analysis of samples consisted in measuring consistency, viscosity, colour and physicochemical characteristics of the treated and fresh puree. Applying intense treatments (600 W-340 s, 900 W-300 s and 1,000 W-200 s) through high power or long treatment periods or a combination of these factors, mainly affects the consistency (flow distance decreased from 5. 9 to 3. 4 mm/g sample), viscosity (increased from 1. 6 to 2. 5 Pa/s), colour (maximun ¿E was 6 U) and taste of the product. As a result, samples were thicker and with an atypical flavour and kiwifruit colour due to increased clarity (L* increased from 38 to 43) and slight changes in the yellow-green hue (h* decreased from 95 to 94). For the instrumental determinations of colour and visual perception of consistency, the most suitable parameters for quality control are the colour coordinates L*, a*, h*, whiteness index and flow distance measured with a Bostwick consistometer. © 2011 Springer Science+Business Media, LLC.The authors thank the Ministerio de Educacion y Ciencia for the financial support given throughout the Project AGL 2010-22176. The authors are indebted to the Generalitat Valenciana (Valencia, Spain) for the Grant awarded to the author Maria Benlloch. The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain.Benlloch Tinoco, M.; Varela Tomasco, PA.; Salvador Alcaraz, A.; Martínez Navarrete, N. (2012). Effects of Microwave Heating on Sensory Characteristics of Kiwifruit Puree. Food and Bioprocess Technology. 5(8):3021-3031. https://doi.org/10.1007/s11947-011-0652-1S3021303158Albert, A., Varela, P., Salvador, A., & Fiszman, S. M. (2009). 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Assessment of microwave energy for disinfestation of grain Written for presentation at the CSAE/SCGR 2005 Meeting

Abstract. Infestation of grain by insects is widely controlled by the use of insecticides. Use of contact insecticides results in chemical residues left in the food which may have adverse effects on humans. Also insects develop resistance to both contact insecticides and fumigants. Microwave disinfestation offers an alternate way to disinfest grain. Microwaves are electromagnetic waves with frequencies ranging from 300 MHz to 300 GHz. The use of microwaves for killing insects is based on the dielectric heating of insects present in grain, which is a relatively poor conductor of electricity. There is a possibility of selective heating of insects in grain because of a significant difference in dielectric constants between grain and insects. The major advantage of using microwave energy is that no chemical residues are left in the food and insects are unlikely to develop resistance to this treatment. Principle of microwave disinfestation, experimental results from previous studies and the advantages of using microwaves for disinfestation of grain are discussed

The Canadian Society for Bioengineering La Société Canadienne de Génie Agroalimentaire et de Bioingénierie Disinfestation of life stages of Tribolium castaneum in wheat using microwave energy Written for presentation at the CSBE/SCGAB 2006 Annual Conferen

Abstract Insecticide residues have adverse effects on humans, and insects develop resistance to insecticides. Hence there is a need for an alternate method for disinfestation of grain. Disinfestation of grains using microwaves can be an alternate method to insecticides for killing insects. A method to control Tribolium castaneum (Herbst) in wheat using microwave energy is described in this manuscript. An industrial microwave system operating at 2.45 GHz was used to determine the mortality of life stages of T. castaneum. Wheat samples of 50 g each at 14, 16, and 18% moisture content (wet basis) were infested with 5 and 10 insects. The infested samples were then exposed to microwaves at four different power levels of 250, 300, 400, and 500 W for two exposure times of 28 and 56 s. One hundred percent mortality was achieved at 400 W for eggs and for larvae, pupae and adult at 500 W. The mortality rates were lower at the lower power levels and shorter exposure time. Among the life stages, eggs were most susceptible followed by larvae, adult and pupae. Germination of wheat kernels was lowered after treatment with microwave energy