Investigation of the effect of beef moisture content on the amount of bound moisture with the calorimetric method

Abstract

With the development of food processing and storage at near-cryoscopic temperatures, more and more attention is being paid to the development of methods for frozen out moisture and cryoscopic temperature calculating based on their component composition data. There is a significant dispersion among the existing experimental data of various researchers and calculation methods for beef thermophysical properties. In the study given, the authors determined the enthalpy of phase transitions, beet heat capacity with different moisture content and its cryoscopic temperature with the method of differential scanning calorimetry. With the analysis of the phase transitions enthalpy, it was found out that the share of non-freezing water for beef is n = 0.35 (g of water per 1 g of dry matter). The presence of the vitreous phase in the temperature range of about -85 ° С was established, most noticeably manifested when the moisture content of the samples is w = 37–45.8%, which indicates the formation of amorphous solutions in the process of food products freezing. Beginning of moisture melting peak Tm.b. takes place at temperatures range from -35 ° C till -25 ° C for the samples with low and normal moisture content respectively. Acccording to the theoretical Heldman ratio, a dependence for cryoscopic temperature calculating was proposed . The given semi-empirical dependences of the phase transitions enthalpy and the frozen moisture fraction provide an increase in the accuracy of calculations at low values of moisture content in the product. The research results can be used as input data in mathematical modeling of heat exchange processes and the development of calculating methods for the thermophysical properties of food products based on their composition.

Thermal conductivity factor for beef of NOR and DFD grades at the subcryoscopic temperatures

“…The results of the measurements are in satisfactory agreement with the data of V. P. Latyshev [18]. Earlier experiments [30] showed that at temperatures below minus 35 °C, the amount of frozen moisture in meat remains almost unchanged. Taking this into account, a formula was developed for calculating the amount of frozen moisture (3).…”

“…The temperature deviation from the initial temperature of the sample measured by the sensor makes it possible to calculate the thermal conductivity of the material under study according to the relationship: 0.9 °C [28]. At the temperatures close to cryoscopic temperature, the amoun in meat of different grades may vary by more than 30% [29,30,31].…”

“…With an increase in the pH of beef from 5.5 to 6.9, the cryoscopic temperature increases from minus 1.5 °C to minus 0.9 °C [28]. At the temperatures close to cryoscopic temperature, the amount of frozen moisture in meat of different grades may vary by more than 30% [29,30,31].…”

Calculation of Heat Capacity in Meat During Its Freezing Considering Phase Change

“…Recently, several studies were conducted on processes of freezing and thawing, considering their effect on product quality [11,12,13,14,15,16,17,18,19,20].…”