Radio frequency heating of comminuted meats - considerations in relation to microbial challenge studies

Production of Marinated Chinese Lotus Root Slices Using High-Pressure Processing as an Alternative to Traditional Thermal-and-Soaking Procedure

Marinated vegetables are traditional cold dishes with a long history and special flavor in the Chinese deli market. However, the traditional thermal-and-soaking (TS) procedure often results in unreproducible flavor quality properties of marinated vegetables and waste of brine and time in production. A novel green and sustainable technique, high-pressure processing (HPP), has caught the attention of the food industry. In this study, the effects of HPP and TS treatment on the visual, flavor, textural, and microbiological qualities of Chinese marinated lotus root slices were investigated. Compared to the TS products, lighter color, more varieties of volatile compounds, and crunchier texture were detected in the HPP products. Throughout the 4 °C, 25 °C, and 45 °C shelf life challenges, the HPP products retained their original color and crunchiness better than the TS ones, whereas no significant differences were found in total viable counts (TVCs) in the first half of the shelf lives. The Arrhenius model under the first-order reaction of TVC deterioration showed a good fit to the shelf life of the HPP marinated lotus root slices. This study demonstrates that HPP may assist in making the best use of brine in a more time-efficient manner to improve the visual, flavor, and textural quality of traditional Chinese marinated lotus root slices.

Radio frequency pasteurization and heating uniformity of canned pineapple

This research investigated heating uniformity and pasteurization of canned pineapple using radio frequency (RF) energy. Experiments were conducted in a 6 kW, 27.12 MHz pilot-scale RF system. Results showed that the temperature difference was more than 16°C, and the standard deviation was 4.38°C at the end of heating when using RF heating alone. Water bath-assisted RF (WRF) heating effectively improved the heating uniformity, the temperature difference was less than 7°C and the standard deviation was 2.52°C at the end of heating in the condition of electrode gap (210 mm), chord length of the fruit block (26 mm), and the initial temperature of sugar solution (80°C). When the total number of colonies reached 4-log reduction, water bath (WB) heating alone needed 660 s, and WRF heating needed 180 s. Vitamin C, hardness, and color of fruit blocks were well preserved using WRF heating compared with WB alone. PRACTICAL APPLICATION: This study shows that the pasteurization of canned food by radio frequency heating can achieve better food quality than the traditional pasteurization methods. Therefore, this research can promote the application of radio frequency heating technology in canned food pasteurization.

Pasteurization of flavored shredded pork using Zno nanoparticles combined with radio frequency pasteurization technology

Effects of ZnO nanoparticles combined radio frequency (ZNCRF) pasteurization on the survival of microorganism, flavor and taste of Flavored shredded pork were compared with conventional high pressure steam (HPS) sterilization. The results showed that ZNCRF pasteurization was better than HPS sterilization in terms of flavor and taste parameters and at the same time met the pasteurization requirement. GC-MS and NMR measurements were performed to explore changes in volatile compounds and status and distribution of water within the sample. The ZNCRF pasteurization when carried out for 30 min and the HPS sterilization reduced the relative contents of aldehydes by 18.8% and 19.7%, respectively, while the ZNCRF pasteurization within 20 min had less effect on aldehydes. Both ZNCRF pasteurization and HPS sterilization destroyed the vacuolar membrane of the samples caused the loss of water from the cytoplasm (T₂₃). This work shows that ZNCRF when applied for 20 min is a mild pasteurization method that can be applied to improve the quality of Flavored shredded pork.

Emerging Meat Processing Technologies for Microbiological Safety of Meat and Meat Products

A consumer trend toward convenient, minimally processed meat products has exerted tremendous pressure on meat processors to ensure the safety of meat and meat products without compromising product quality and the meeting of consumer demands. This has led to challenges in developing and implementing novel processing technologies as the use of newer technologies may affect consumer choices and opinions of meat and meat products. Novel technologies adopted by the meat industry for controlling foodborne pathogens of significant public health implications, gaps in the technologies, and the need for scaling up technologies that have been proven to be successful in research settings or at the pilot scale will be discussed. Novel processing technologies in the meat industry warrant microbiological validation prior to becoming commercially viable options and enacting infrastructural changes. This review presents the advantages and shortcomings of such technologies and provides an overview of technologies that can be successfully implemented and streamlined in existing processing environments.

The effect of radio-frequency heating on vacuum-packed saury (Cololabis saira) in water

We characterized vacuum-packed whole saury (Cololabis saira) treated using radio-frequency (RF) heating and compared it with that treated using conventional retort heating. RF heating is electrical heating based on dielectric heating. In this study, the effect of RF heating on softening and collagen in backbone was analyzed. RF heating heated the center of fish faster than water. The backbone was softened to a chewable level, and the heating time was shortened to one-third. The amount of crude protein and collagen in backbone decreased with decreasing elasticity, although that heated using RF (131°C) still contained a higher amount than conventional heating. However, β and γ collagen, and then α1 and α2 collagen chain in backbone disappeared with heating; therefore, collagen was degraded to collagen peptide. Results confirmed that RF heating provided wholly eatable fish containing low-molecular collagen peptide in a short heating time.

Effects of radio frequency and high pressure steam sterilisation on the colour and flavour of prepared Nostoc sphaeroides

BACKGROUND

Nostoc sphaeroides has been used as a highly effective herbal medicine and dietary supplement for thousands of years. The desired dark green colour of fresh N. sphaeroides is converted into an undesirable dark brown during conventional high pressure (HP) steam sterilisation. Radio frequency (RF) sterilisation technology was used in this study to determine its effectiveness in sterilising N. sphaeroides and to achieve better preservation of natural colour and desirable flavour. Sterilisation was carried out using a 6 kW, 27 MHz RF instrument for 10, 20 and 30 min. The degree of microbial kill and the effects of RF sterilisation on colour and flavour were determined and compared with those obtained from HP steam (121 °C, 30 min) sterilisation.

RESULTS

The effects of RF sterilisation on colour and flavour (measured using electronic nose) parameters were significantly lower than that in HP steam sterilisation. The RF sterilisation carried out for 20 min achieved logarithmic reduction of bacterial population and met China's national standard while preserving the colour and flavour better.

CONCLUSION

Results of the present study indicated that application of RF sterilisation would improve the quality of sterilised N. sphaeroides and broaden its application in the food and health food industries. © 2017 Society of Chemical Industry.

Effect of marination in gravy on the radio frequency and microwave processing properties of beef

Dielectric properties (the dielectric constant (ε') and the dielectric loss factor (ε″)) and the penetration depth of raw eye of round beef Semitendinosus muscle, raw beef marinated in gravy, raw beef cooked in gravy, and gravy alone were determined as a function of the temperature (20-130 °C) and frequency (27-1,800 MHz). Both ε' and ε″ values increased as the temperature increased at low frequencies (27 and 40 MHz). At high frequencies (915 and 1,800 MHz), ε' showed a 50 % decrease while ε″ increased nearly three fold with increasing temperature in the range from 20 to 130 °C. ε' increased gradually while ε″ increased five fold when the temperature increased from 20 to 130 °C. Both ε' and ε″ of all samples decreased with increase in frequency. Marinating the beef in gravy dramatically increased the ε″ values, particularly at the lower frequencies. Power penetration depth of all samples decreased with increase temperature and frequency. These results are expected to provide useful data for modeling dielectric heating processes of marinated muscle food.