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Starches from sixteen cassava germplasms harvested at the same time in the Hainan region were evaluated for their physicochemical and structural properties. The granule morphology of all the isolated cassava starch samples showed round, bell or oval shapes and exhibited the same A-type crystalline pattern. The crystallinity range was 26.6-30.8%. The selected cassava germplasms showed a wide variation in granule size distribution: The D[4,3] (the average particle size) ranged from 13.49 µm to 306.27 µm. The water absorption capacity (192.6-226.7%), oil absorption capacity (185.-0-216.9%) and transparency (6.8-16.5%) indices varied significantly among the cassava germplasms. However, the retrogradation rates of the cassava starch pastes increased rapidly during the first 1 h and then stabilized. The solubility of starch increased with the temperature. In addition, the FTIR (Fourier Transform Infrared Spectrometer) ratios of 1045/1022 cm-1 and 1022/995 cm-1 of the sixteen cassava starches varied in the range of 1.06-1.78 and 0.78-1.04, respectively. These results indicated that the granule size, relative crystallinity, degree of short-range order, water and oil absorption capacities, solubility and transparency of the cassava starches were greatly influenced by the variety of cassava, which could help in determining the advantages of these starches for applications in different food and nonfood industries. [ABSTRACT FROM AUTHOR]

Dielectric properties of sliced Agaricus bisporus samples, with 0.16-0.89 [g/g, wet basis (w.b.)] moisture content, were determined using a network analyser and an open-ended coaxial-line probe, over a frequency range of 915 MHz to 2450 MHz and a temperature range of 25°C to 60°C. The results showed that the permittivity of A. bisporus was a function of frequency, moisture content, and temperature. The dielectric constant and loss factor were directly proportional to moisture content and temperature, respectively, and both decreased with increasing frequency. However, the influence of temperature on the dielectric constant showed a different trend, as this was affected by the moisture content of the sample. The dielectric loss factor initially increased and then decreased with the decrease in moisture content. Both inflection points appeared at the moisture content value of 0.69 (g/g, w.b.), which represents the "semi-bound water transfer" point. Third-degree polynomial models could be used to describe dielectric constant and loss factor values as functions of moisture content and temperature. The penetration depth decreased with increasing frequency and temperature; however, this first decreased with decreasing moisture content and then increased. Notably, the penetration depth was at a low ebb when the moisture content ranged from 0.69 to 0.52 (g/g, w.b.), indicating easier uneven drying. Low frequency (915 MHz) with large penetration depth represents a highly effective method for large-scale industrial dielectric microwave drying of A. bisporus slices from the angle of uniformity. [ABSTRACT FROM AUTHOR]