Food Properties and Processing Theory

Food Properties and Processing Theory

• Food texture can be assessed using sensory methods, including taste panels and quantitative descriptive analysis.
• Numerical texture profiling can involve quantifying the force required to shear, penetrate, extrude, compress or cut a food.
• Mass transfer is crucial in food processing, influencing operations like solvent extraction, distillation, membrane processing, and blanching.
• Mass transfer of gases and vapors is key during evaporation, dehydration, baking, roasting, frying, freeze drying, freezing, and maintaining quality in chilled, MAP, and packaged foods.
• The rate of mass transfer is influenced by the driving force and the resistance to the flow of materials.
• Common sources of energy in food processing include electricity, natural gas, liquid petroleum gas, and liquid fuel oil.
• Heat processing is a preservation method that denatures proteins, thereby destroying enzyme activity and enzyme-controlled metabolism in microorganisms.
• Microbial destruction follows a first-order reaction, meaning the same percentage of microorganisms die within a given time interval regardless of their initial number. This is known as the logarithmic order of death.
• The decimal reduction time (D value) is the time required to reduce the number of microorganisms by a factor of 10 (90% reduction).
• The D value is dependent on the type of microorganism and the temperature.
• The thermal death time (TDT) curve represents the relationship between temperature and D value.
• The z value is the temperature change required to achieve a tenfold change in the D value, reflecting the temperature dependence of microbial destruction.
• The recovery of microorganisms in heat resistance studies is influenced by the growth media and incubation conditions.
• The concept of commercial sterility aims to reduce the number of surviving microorganisms to an acceptable level, not necessarily eliminating all microorganisms.
• Heat treatment can affect both nutritional and sensory characteristics of foods, often following a first-order reaction.
• The impact of heat on nutritional and sensory properties can be minimized by using higher temperatures and shorter processing times.
• The concept of high-temperature short-time (HTST) processing is based on minimizing the impact of heat on food quality.
• Water activity (aw) is a measure of the availability of water for microbial, enzymatic, or chemical activity in a food.
• Low aw inhibits microbial activity, with specific thresholds for different microorganisms (e.g., most bacteria below 0.9, most yeasts below 0.8, most fungi below 0.7, and almost all microbial activity inhibited below 0.6).
• Factors such as temperature, pH, oxygen, carbon dioxide, and chemical preservatives can influence the effectiveness of aw in inhibiting microbial growth.
• Unit operations that reduce water availability in foods include dehydration, evaporation, freeze drying, freeze concentration, and the use of humectants.
• The interaction between aw and other factors (temperature, pH, oxygen, etc.) plays a major role in controlling microbial growth and food spoilage.

This quiz covers essential concepts in food properties and processing, focusing on texture assessment, mass transfer, and heat processing methods. You'll learn how different processing techniques affect food quality and preservation. Test your knowledge on key operations like extraction, evaporation, and baking.