Contactless monitoring of food drying and freezing processes with millimeter waves

Optimizing Harvesting Efficiency: Development and Assessment of a Pneumatic Air Jet Excitation Nozzle for Delicate Biostructures in Food Processing

This study presents a new pneumatic air jet excitation nozzle, specifically designed for food processing applications. The device, which uses compressed air equipment and a precision solenoid valve, controls air discharge through a parametric air jet nozzle. Tests showed that the device could achieve shooting frequencies in the 40-45 Hz range, with operational pressures between 5 and 7 bar. A sensor system was used to measure the force generated by the device at different frequencies and pressures. Using the Design of Experiments (DOE) methodology, we identified optimal cavity designs for 5 and 6 bar pressures. These designs outperformed others in generating uniform force and maintaining consistent vibration voltage behavior. This highlights the efficacy of our approach in enhancing device performance under different conditions. The device's practical application in food processing was demonstrated, particularly in delicate tasks such as the selective harvesting of sensitive crops like coffee fruits. The precise vibrations generated by the device could potentially enhance harvesting efficiency while significantly reducing mechanical damage to plants. The results position the device as a compelling proof of concept, offering an alternative method for exciting biostructures in food processing. This device opens up new possibilities in agricultural and biological fields, providing a non-intrusive and practical approach to manipulating and interacting with delicate, contactless structures, with a specific focus on improving food processing efficiency and quality.

Ice crystallization and structural changes in cheese during freezing and frozen storage: implications for functional properties

Temperature-mediated preservation techniques offer a simple, scalable, effective, and fairly efficient method of long-term storage of food products. In order to ensure the uninterrupted availability of cheese across the globe, a critical understanding of its techno-functional properties as affected by freezing and frozen storage is essential. Detailed studies of temperature-mediated molecular dynamics are available for relatively simpler and homogeneous systems like pure water, proteins, and carbohydrates. However, for heterogeneous systems like cheese, inter-component interactions at sub-zero temperatures have not been extensively covered. Ice crystallization during freezing causes dehydration of caseins and the formation of concentration gradients within the cheese matrix, causing undesirable changes in texture-functional attributes, but findings vary due to experimental conditions. A suitable combination of sample size, freezing rate, aging, and tempering can extend the shelf life of high- and low-moisture Mozzarella cheese. However, limited studies on other cheeses suggest that effects and suitability differ by cheese type, in most cases adversely affecting texture and functional attributes. This review presents an overview of the understanding of the effects of refrigeration, freezing techniques, and frozen storage on structural components of cheese, most prominently Mozzarella cheese, and the corresponding impact on microstructure and functionality. Also included are the mechanism of ice formation and relevant mathematical models for estimation of the thermophysical properties of cheese to assist in designing optimized schemes for their frozen storage. The review also highlights the lack of unanimity in critical understanding concerning the effect of freezing on the long-term storage of Mozzarella cheese with respect to its functionality.

Glass transitions in frozen systems as influenced by molecular weight of food components

Freezing is a frequently used way to expand the storage life of foods with high water content. Under suitable cooling rates, frozen systems attain a condition of maximum freeze concentration, which is characterized by the glass transition temperature (T_g '), end point of freezing or onset of melting (T_m '), and concentration of solids (X_s ') in the maximum-freeze-concentrated matrix. The value of T_g ', T_m ', and X_s ' depends on the chemical composition of frozen system. Below T_g ', the rates of deteriorative reactions are significantly reduced. In this article, the data for T_g ', T_m ', and X_s ' of different frozen systems including sugars, starches, proteins, and food are collected and compiled. The trends in T_g ' and T_m ' data of food are investigated using molecular weight (MW) of food components. The T_g ' and T_m ' of most starches (increased by 2.46% to 87.3% and 10.8% to 85.0%) and some protein-rich foods (increased by 5.00% to 53.4% and 25.0% to 52.9%) were higher than the maximum values of sugar-rich foods. Both T_g ' and T_m ' values increased with increasing MW of solids in frozen food, reaching an asymptotic value. Moreover, there were exponential relationships between T_g ' or T_m ' values and MW for sugar and starch-rich foods taken together. Some studies found that frozen storage below T_g ' maintains the higher quality of food that was achieved by fast freezing. However, other studies found that there was no significant difference in the quality of frozen foods between storage temperature below and above T_g '. Therefore, storage below T_g ' is not the only factor for predicting the stability of frozen foods.