A strategy for improving the uniformity of radio frequency tempering for frozen beef with cuboid and step shapes

Advancements and perspectives of novel freezing and thawing technologies effects on meat: A review

Freezing is an effective method to extend the shelf life of meat. Traditional slow freezing technologies tend to damage muscle cells due to the formation of large ice crystals. Before further processing, frozen meat needs to undergo a thawing process. Traditional thawing technologies require long thawing times, which may increase the drip loss and accelerate the bacterial growth rate. Quality deterioration and nutrient reduction are common problems in frozen meat. To produce high-quality frozen meat, novel freezing and thawing technologies have been developed constantly over the past decades. This review investigated the effects of eight novel freezing technologies and seven novel thawing technologies on frozen meat quality. Novel freezing technologies with rapid freezing rates contribute to forming small and uniformly distributed ice crystals, thereby reducing the damage to muscle cells. Some novel thawing technologies increase the thawing efficiency by exposing the meat to energy fields to heat all parts of the meat concurrently. Additionally, the principles of these technologies are summarized. Single-method freezing and thawing have limitations in preserving the quality of fresh meat. Therefore, this review also discussed the potential application of combined freezing/thawing technologies, which can better maintain moisture distribution, reduce color and texture changes, and lower lipid and protein oxidation. Many challenges remain in the exploitation of novel freezing/thawing technologies. Further research could focus on investigating the mechanisms and industrial applications of these technologies, establishing models to describe freezing/thawing processes, and exploring different freezing/thawing equipment based on differences in myofibril structure and tissue moisture content.

Electrostatically-enhanced two-stage low-temperature tempering: Effects on the quality of frozen tan mutton

The two-stage low-temperature tempering (TLT) and TLT assisted by electrostatic fields (TLT-1500/2000/2500/3000) were developed to investigate their effects on the quality of frozen Tan mutton. The results demonstrated that both TLT and TLT-1500/2000/2500/3000 significantly (P < 0.05) enhanced the tempering rate compared to refrigerator tempering (4 °C, RT). The analysis of tempering, cooking, and centrifugal losses, along with the evaluation of electrical conductivity, pH, and TVB-N, showed that the water retention capacity and freshness of Tan mutton treated with TLT-2500 were closest to those of fresh Tan mutton. Scanning electron microscopy analysis demonstrated that TLT-2500 best maintained the tissue integrity of Tan mutton, while low-field nuclear magnetic resonance analysis revealed it contained the highest immobile water and least free water. Furthermore, Tan mutton treated with TLT-2000 and TLT-2500 exhibited minimal lipid oxidation and color change. In contrast, the most significant changes in all indicators were observed after RT.

Evaluation of the Improvement Effect of Whey Protein Poly-Peptides on Quality Characteristics of Repeated Freeze-Thawed Spanish Mackerel Surimi Balls

This investigation aimed to assess the effects of whey protein hydrolysate (WPH) on the oxidative stability of protein and the ability of Scomberomorus niphoniu surimi balls to retain water after repeated freeze-thaw (F-T) cycles. Ten percent natural whey peptides (NWP), 5% WPH, 10% WPH, 15% WPH, 0.02% butyl hydroxyl anisole (BHA), and a control group that did not receive any treatment were the six groups that were employed in the experiment. The cooking loss, water retention, total sulfhydryl content, and carbonyl content of each group were all measured. Notably, it was found that the surimi balls' capacity to hold onto water and fend off oxidation was enhanced in a dose-dependent manner by the addition of WPH. Furthermore, the results showed that the 15% WPH added to the surimi balls effectively decreased protein oxidation in the F-T cycles and ameliorated the texture deterioration of surimi balls induced by repeated F-T, laying a theoretical foundation for the industrial application of WPH in surimi products.

Evaluation of Pilot-Scale Radio Frequency Heating Uniformity for Beef Sausage Pasteurization Process

Radio frequency (RF) heating has the advantages of a much faster heating rate as well as the great potential for sterilization of food compared to traditional thermal sterilization. A new kettle was designed for sterilization experiments applying RF energy (27.12 MHz, 6 kW). In this research, beef sausages were pasteurized by RF heating alone, the dielectric properties (DPs) of which were determined, and heating uniformity and heating rate were evaluated under different conditions. The results indicate that the DPs of samples were significantly influenced (p < 0.01) by the temperature and frequency. The electrode gap, sample height and NaCl content had significant effects (p < 0.01) on the heating uniformity when using RF energy alone. The best heating uniformity was obtained under an electrode gap of 180 mm, a sample height of 80 mm and NaCl content of 3%. The cold points and hot spots were located at the edge of the upper section and geometric center of the sample, respectively. This study reveals the great potential in solid food for pasteurization using RF energy alone. Future studies should focus on sterilization applying RF energy and SW simultaneously using the newly designed kettle.

Effect of Load Spatial Configuration on the Heating of Chicken Meat Assisted by Radio Frequency at 40.68 MHz

Food heating assisted by radio frequencies has been industrially applied to post-harvest treatment of grains, legumes and various kind of nuts, to tempering and thawing of meat and fish products and to post-baking of biscuits. The design of food processes based on the application of radiofrequencies was often based on rules of thumb, so much so that their intensification could lead significant improvements. One of the subjects under consideration is the shape of the food items that may influence their heating assisted by radiofrequency. In this work, a joint experimental and numerical study on the effects of the spatial configuration of a food sample (chicken meat shaped as a parallelepiped) on the heating pattern in a custom RF oven (40.68 MHz, 50 Ohm, 10 cm electrodes gap, 300 W) is presented. Minced chicken breast samples were shaped as cubes (4 × 4 × 4 cm3) to be organized in different loads and spatial configurations (horizontal or vertical arrays of 2 to 16 cubes). The samples were heated at two radiofrequency operative power levels (225 W and 300 W). Heating rate, temperature uniformity and heating efficiency were determined during each run. A digital twin of the experimental system and process was developed by building and numerically solving a 3D transient mathematical model, taking into account electromagnetic field distribution in air and samples and heat transfer in the food samples. Once validated, the digital tool was used to analyze the heating behavior of the samples, focusing on the most efficient configurations. Both experiments and simulations showed that, given a fixed gap between the electrodes (10 cm), the vertically oriented samples exhibited a larger heating efficiency with respect to the horizontally oriented ones, pointing out that the gap between the top electrode and the samples plays a major role in the heating efficiency. The efficiency was larger (double or even more; >40% vs. 10−15%) in thicker samples (built with two layers of cubes), closer to the top electrode, independently from nominal power. Nevertheless, temperature uniformity in vertical configurations was poorer (6−7 °C) than in horizontal ones (3 °C).