Mechanisms of Heat Transfer During Food Production

Thermal conductivity is one of the unifying properties of a food product that affects heat treatment success. Thermal conductivity is highly dependent on the material's moisture content, temperature, and physical molecular arrangement.

FREMONT, CA: Humans are naturally predisposed to seek sugary things, and this craving only intensifies as we age. When confronted with the exceedingly difficult question of their opinions on chocolate, most people react with delight. Their responses frequently express how much they savor this delectable gift. Their faces will light up as they anticipate the milky, smooth flavor of their favorite chocolate bar and how eager they are to get their hands on a piece of that delicious goodness. This passion for chocolate and sweet items, in general, has propelled the confectionery industry's prosperity in the United States, which was valued at more than USD 34.5 billion in 2020. Confectionery products include cookies, chocolate, gummy bears, and chewing gum. Unsurprisingly, chocolate sales exceed USD 21.1 billion in the confectionery business, accounting for slightly more than 60 percent of total sales. It is reasonable to suppose that society places a premium on the quality of the items manufactured by candy manufacturing enterprises. Effective heat management during processing is a critical factor in the success of chocolate and candy production.

Thermal processing is unquestionably a critical component of the food production business. The thermal processing idea is based on heating foods at a predetermined temperature for a predetermined period. This processing application aims to enhance food goods' eating quality and safety by extending their shelf life and eliminating potentially hazardous microbes. The textbook definitions of food heat treatment methods emphasize the importance of utilizing various techniques, such as blanching, cooking, drying, pasteurization, sterilization, and thawing. All of these procedures rely heavily on a thorough understanding of the thermophysical characteristics of food. Specific heat, thermal conductivity, thermal diffusivity, freezing point, and freezing range are the primary qualities of a food product.

Conduction

The success of thermal treatment on food products is contingent upon the materials' ability to withstand an increase in temperature. Heat transfer takes place in properly built equipment that has been engineered to perform the required thermal treatment. Conduction, radiation, and convection all contribute to heat transmission in these machines. Conduction is the transfer of kinetic energy from molecule to molecule or from surface to surface. Due to the intake of heat, one molecule will become energized and transmit a portion of this energy to a nearby molecule with a lower energy level. When one cooks an egg in a cast iron metal skillet, this is an example of conduction heat transfer. The heat generated by the hot stove transfers energy to the thermally conductive metal pan, energizing its molecules. These high-energy molecules are what transfer the energy required to cook an egg. Conduction is used in the food processing sector to cook generally semi-solid foods and not move (for example, pie filling or tomato paste stored in a can).

Radiation

Thermal radiation is produced when electromagnetic waves are emitted from an emitting object or thermal body. Our skin emits infrared radiation, a kind of heat and energy. To some extent, all materials emit thermal energy in response to their internal resting temperature. Naturally, the hotter a thing is, the more heat it will emit.

Typically, one or more heat transfer processes occur during food processing, production, and packing. The thickness of the walls of shipping containers is critical in limiting heat transfer or loss by conduction. When designing food packaging, reflective materials such as aluminum can affect a product's radiation sensitivity. Any material that exhibits high resistance to heat transfer by conduction, radiation, or convection is considered an insulator and often has a very low thermal conductivity. This heat resistance can be advantageous in limiting enzyme and microbe growth, but it presents a barrier for manufacturers when designing appropriate thermal treatment applications.