Title : Investigating the effects of superchilling storage on the microstructure of beef meat.
Abstract:
Superchilling offers a promising approach to extending the shelf life of fresh products beyond conventional chilling, without the adverse effects associated with freezing. The final quality of the product is primarily determined by the ice volume fraction and the properties of ice crystals, including their size, distribution, and location. To maintain optimal product integrity, the ice volume fraction must be precisely controlled within the range of 30% to 35% during superchilled storage. Additionally, ice crystals should be uniformly distributed throughout the product, and their growth must be minimized to preserve texture and quality.
Beef meat samples were partially frozen in an air blast freezer at ‒30°C (air temperature) and 58 W/m2 K for 9 minutes prior to storage under different temperature conditions of ‒1.8°C, ‒2.8°C, ‒4°C, and ‒5°C for 21 days. The aim of this work was to study the microstructure of beef during superchilled storage. X-ray microtomography (µCT) which is an advanced 3D imaging technique was used to visualize and quantify the evolution of ice crystals in superchilled beef meat samples during storage. This method provided in-depth analysis of ice volume fractions, ice crystal size and number as well as ice crystal distribution in terms of cumulative probability density functions. The analysis was done at four distinct time points: days 1, 7, 15, and 21.
The average initial ice volume fraction of the pre-frozen sample was 31% ± 0.01 at day 0 (obtained immediately after partial freezing. Our results showed that both storage time and storage temperature had a significant impact on the microstructure of the beef meat. Moreover, a progressive growth of ice crystals was observed during storage, as evidenced by cumulative probability curves that depicted a higher proportion of larger ice crystals at ‒4°C and ‒5°C compared to ‒1.8°C and ‒2.8°C. These findings emphasize the importance of investigating microstructural evolution in superchilled storage because they have a direct impact on the final beef quality. Moreover, the use of a non-destructive 3D method for describing microstructure evolution during superchilled storage provided insights that will lead to a better control of the quality and safety of food throughout the cold chain.
