Drying kinetics using superheated steam and quality attributes of dried pork slices for different thickness, seasoning and fibers distribution

Effect of microwave vacuum drying time on the quality profiles, microstructures and in vitro digestibility of pork chip snacks

In present study, the quality profiles, microstructures and in vitro digestibility of pork chip snacks (PCS) prepared by microwave vacuum drying (MVD) under different drying times (20, 21, 22, 23, and 24 min) were investigated. The results revealed significant decreases in the moisture content and L*-value of PCS, while the protein/ash contents, a*-value, and b*-value of PCS markedly increased with prolonged MVD time (P < 0.05). Additionally, as MVD time extended from 20 to 24 min, the textural characteristics of PCS, particularly brittleness and crunchiness, initially increased and then gradually decreased (P < 0.05). Scanning electron microscopy (SEM) images showed that a moderate MVD time (22 min) resulted in the formation of larger pores in PCS, enhancing brittleness and crunchiness. However, excessive MVD time (24 min) led to the melting of these pores, subsequently reducing the brittleness and crunchiness of PCS. Furthermore, in vitro protein digestibility of PCS gradually decreased with increasing MVD time, primarily attributed to increased protein aggregation, as indicated by changes in sulfhydryl contents. In summary, our findings highlight that PCS subjected to 22 min of MVD exhibited the highest overall acceptability. This study provides a novel strategy for the application of MVD in the processing of meat snacks.

Drying dynamics of meat highlighting areas of relevance to dry-aging of beef

Drying of foods is a processing step, which has a variety of outcomes from improving shelf life and product stability, to reducing weight, or to achieving a targeted product eating quality. Drying is key step in the manufacturing of some dried meat products, such as jerky. It is also a major event that occurs when beef is dry-aged, where beef is exposed to air under defined conditions for an extended aging period. Although the conditions typically used to produce dried meat products are significantly different from those that prevail during dry-aging, both involve a gradual removal of water from muscle. As there is a paucity of research on the kinetics of the dehydration process occurring during dry-aging of beef, this paper comprehensively reviews models used to describe drying kinetics in other beef products, in order to gain insights regarding the key factors that impact water removal from meat. Consideration is given as to how the specific conditions during dry-aging such as air flows used (approximately 2 m/s), high air relative humidity, low temperature, and meat geometry will influence the kinetics of the drying. With regard to modeling, equations derived from Fick's second law of diffusion (e.g., thin-layer models) have been used to describe the drying kinetics of small-sized meat products. However, to apply Fick's law to dry-aging, some different considerations may need to be evaluated such as: tridimensional geometry (i.e., whole muscle); uniform initial moisture content; isotropic diffusion; negligible shrinkage;and a combination of internal and external resistances.

Effects of NaCl content and drying temperature on lipid oxidation, protein oxidation, and physical properties of dry-cured chicken

This study aimed to investigate the effects of different NaCl content and drying temperatures on the lipid oxidation, protein oxidation, and physical properties of dry-cured chicken. In the final product, lipid oxidation, protein oxidation, and physical properties were significantly affected by NaCl and temperature. Increased NaCl content and temperature led to significantly increased level of indicators including conjugated diene, thiobarbituric acid reactive substances, and carbonyl contents (P < 0.05). Conversely, the sulfhydryl contents and surface hydrophobicity significantly decreased (P < 0.05). Results of sodium dodecyl sulfate polyacrylamide gel electrophoresis further indicated that NaCl and temperature affected protein oxidation and degradation. According to the drying curve, the main factor affecting the drying time was the drying temperature and a slower rate of moisture loss occurred in samples with higher NaCl content. Moreover, due to the effects of temperature on lipid and protein oxidation and moisture diffusion, the hardness and shrinkage ratio increased with temperature. PRACTICAL APPLICATION: Dry-cured chicken is a kind of air-dried meat product. During actual production of dry-cured chicken, its physicochemical characteristics (e.g., lipid and protein oxidation and texture) are affected by NaCl content and drying temperature. In this study, the NaCl content and drying temperature were found to promote lipid and protein oxidation and have significant effects on texture properties. Therefore, the NaCl content and drying temperature should be controlled to improve the quality of dry-cured chicken.

Drying Modelling, Moisture Diffusivity and Sensory quality of Thin Layer dried Beef

The objective of the present study was to determine the drying kinetics, moisture diffusivity and sensory quality of convective air dried beef. The effect of temperature of drying (30-60°C) and thickness of samples (2.5-10 mm) on the convective thin-layer drying kinetics of beefdried in a cabinet dryer was evaluated. Five semi-theoretical models were fit to the drying experimentaldata with the aim of predicting drying characteristics of beef and fitting quality of models determined using the standard error of estimate (SEE)and coefficient of determination (R2). Determination ofeffective moisture diffusivity (Deff) from the experimental drying datawas done and sensory quality of the optimized dried cooked and uncookedbeef samplesevaluated. Drying time and rate of drying increased with an increasing temperature but decreased with increased slice thickness. However, there was overlapping of drying curves at 40-50°C. Among the selected models, Page model gave the best prediction of beef drying characteristics. Effective moisture diffusivity (Deff) ranged between 4.2337 x 10-11 and 5.5899 x 10-10 m2/s, increasing with an increase in air temperature and beef slice thickness.Of all the sensory parameters evaluated, texture was the only attribute that gave significantly different (P > 0.05) scores between the cooked and uncooked dried beef samples.

Drying Kinetics and Quality Attributes of White Radish in Low Pressure Superheated Steam

In this paper, white radish discs were dried in superheated steam at absolute pressure 95 mbar at four levels of drying temperature from 75 °C to 90 °C. The drying kinetics and various quality attributes of white radish were investigated, compared with the results by vacuum drying. By kinetic modeling of drying processes with Fick’s second law, low pressure superheated steam drying (LPSSD) had slightly lower value of effective moisture diffusivity but higher activation energy than vacuum drying. In comparison with vacuum drying, the rehydration capability of dried samples by LPSSD was better due to porous microstructure. Only 25 % or more the total amount of Vitamin C was preserved after drying to the ultimate moisture content, but it was found that some amount of Vitamin C was taken with the exhaust steam and preserved in the condensate.

Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

This work focused on the effects of the moisture content, slices thickness and microwave power on aspects of energy and exergy, drying kinetics, moisture diffusivity, activation energy, and modeling of the thin layer drying of kiwi slices. Results showed that energy and exergy efficiency increased with increasing microwave power and decreasing slice thickness while values of energy efficiency (15.15-32.27 %) were higher than exergy efficiency (11.35-24.68 %). Also, these parameters decreased with a decrease in moisture content. Specific energy consumption varied from 7.79 to 10.02, 8.59 to 10.77 and 9.57 to16.20 to MJ/kg water evaporated for 3, 6 and 9 mm, respectively. The values of exergy loss were found to be in the range of 5.90 and 14.39 MJ/kg water and decreased as the microwave power increased and slice thickness decreased. Effective diffusivity increased with decreasing moisture content and increasing microwave power and slice thickness. Average effective moisture diffusivity of kiwi slices changes between 1.47 × 10(-9) and 39.29 × 10(-9) m(2)/s within the given variables range. Activation energy (17.96-21.38 W/g) showed a significant dependence on the moisture content. Although the Midilli model showed the best fit, Page's model was selected, since it had almost a similar performance but the model is simpler with two parameters instead of four.