Moisture sorption isotherms and isosteric heat of sorption of dry persimmon leaves

Moisture sorption isotherms of persimmon leaves were determined at 20, 30 and 40 °C using the standard gravimetric static method over a range of relative humidity from 0.06 to 0.9. The experimental sorption curves were fitted by seven equations: Henderson, Halsey, Smith, Oswin, BET, GAB and Caurie. The Halsey, Smith, GAB and BET models were found to be the most suitable for describing the sorption curves. The isosteric heat of sorption of water was determined from the equilibrium data at different temperatures. It decreased as moisture content increased and was found to be a polynomial function of moisture content.The authors acknowledge the support of the Universtitat Politecnica de Valencia.Martínez Las Heras, R.; Heredia Gutiérrez, AB.; Castelló Gómez, ML.; Andrés Grau, AM. (2014). Moisture sorption isotherms and isosteric heat of sorption of dry persimmon leaves. Food Bioscience. 7:88-94. doi:10.1016/j.fbio.2014.06.002S8894

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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Optimization of Fermentation Time in Instant Tea Production

Fermentation should be optimum for the production of good quality tea. One of the methods commonly followed today is based on the amount of theaflavin (TF) formed during fermentation. For this, samples (juice for instant tea (IT) and pressed leaf residue for black tea granules (TG» were collected at specific interval of time during fermentation and the optical density values were determined by a spectrophotometer. Optimum period was indicated by the peak of the curve obtained by plotting optical density (00) values of the sample vs. fermentation time. The optimum fermentation time for IT was I h and for TG was 1.5 h. The amount of TF formed, as indicated by the increase in 00 in juice increased with increase in fermentation time up to 60 min and after that it decreased. Similar trend was found for pressed leaf residue also where the 00 increased up to 90 min. The decrease in theaflavin content beyond a certain time may be due to the conversion of theaflavin to the a FU bigins (TR). The result was emphasized by another experiment in which IT and TG were prepared with different fermentation times, and the prepared samples were analyzed for the quality by a sensory evaluation pane