Food Preservation: Microbial, Chemical, and Thermal Methods with Quality Control

What are the types of reactions involved in food preservation?

Chemical reactions, biological reactions, and microbial growth.

What external agents are used in food preservation?

Thermal energy, chemicals, radiation, high pressure, and electric fields.

What is the purpose of commercial sterilization?

To achieve a shelf-stable food product through a thermal process.

What is the D-value in microbial survival?

The decimal reduction time needed for a 90% reduction in the microbial population.

How does the D-value change?

It changes depending on the species and the magnitude of the external agent.

What does the thermal resistance constant (Z-value) indicate?

The increase in temperature necessary to cause a 90% reduction in the D-value.

What is the thermal death time (F-value)?

The total time required to achieve a stated reduction in a population of vegetative cells or spores.

How is the F-value calculated?

F = (number of log cycles) x D.

What is the significance of Clostridium botulinum in food preservation?

It is a target microorganism in canning due to its ability to form heat-resistant spores.

What is the cold spot in cylindrical containers during sterilization?

For liquid foods, it's 1/3 up from the base; for solid foods, it's at the geometric center.

What factors affect heat penetration during sterilization?

Product factors, container factors, and retort factors.

What is lethality in the context of thermal processing?

A measure of the heat treatment or sterilization process effectiveness.

What is the come-up time in retort processing?

The time required for a retort to reach a minimum required process temperature.

What are the two types of commercial sterilization systems?

Batch and Continuous systems, and Aseptic systems.

What is aseptic processing?

Heating foods in thin layers to achieve lethality before filling into presterilized containers.

What sterilizing agents are used for packaging in aseptic processing?

Steam, peracetic acid (CH3CO3H), and hydrogen peroxide (H2O2).

What are the advantages of pouch-processed systems?

Reduced processing time, lower shipping costs, and better sensory properties.

What are the disadvantages of pouch-processed systems?

Poor physical stability and the need for sophisticated sealing equipment.

What is the primary goal of thermal processing in food preservation?

To kill viable microorganisms, spores, and enzymes.

What is the reference temperature for Clostridium botulinum in thermal processing?

250°F or 121°C.

What is the relationship between the D-value and the F-value?

F-value can be expressed as a multiple of D-values, such as F = 4D for a 99.99% reduction.

What is the importance of pH in food sterilization?

It affects the heat resistance of microorganisms and the overall sterilization process.

What is the role of enzymes in food preservation?

Enzymes can affect food quality and safety, necessitating their inactivation during processing.

What is the significance of the geometric center in solid food sterilization?

It is the location where the cold spot is typically found, crucial for effective heat distribution.

How does microbial survival curve relate to food preservation?

It quantifies the effectiveness of the preservation process over time.

What is the primary method used to sterilize food in aseptic processing?

Heat exchanger, steam injection, steam infusion, and ohmic heating.

What substances are used to sterilize packaging materials in aseptic processing?

Steam, peracetic acid (CH3CO3H), and hydrogen peroxide (H2O2).

Describe the steps involved in aseptic packaging.

UHT treatment of product, aseptic transfer, sterilization of packaging material, sterile surroundings during packaging, and tight hermetically sealed containers.

What is the main advantage of aseptic processing compared to in-container sterilization?

Aseptic processing has a shorter processing time and better retention of sensory characteristics and nutritional value.

What is a key design component of all aseptic packaging systems?

The space where the product is introduced into the package.

What is the driving force behind solid-liquid separations in food processing?

Pressure, vacuum, or centrifugal force.

What is centrifugation used for in food processing?

To separate particles from suspensions based on size, shape, and density.

What is crystallization in the context of food processing?

The process by which solid crystals of a solute are formed from a solution, used in sugar and salt production.

How does distillation work in food processing?

It separates volatile components of a mixture based on differences in their volatility.

What is the purpose of solvent extraction in food processing?

To separate a soluble compound from a solid or liquid matrix using a volatile solvent.

What is the role of evaporation in food processing?

To obtain partial separation of a volatile solvent, commonly water, from non-volatile components.

What are membrane separations used for in the food industry?

To separate proteins from whey, concentrate milk, clarify juices, and concentrate egg products.

What are the main types of membrane filtration?

Microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO).

What does quality refer to in the food industry?

It can refer to the grade of the product or the materials and workmanship involved.

What is variation in the context of food processing?

The deviation between one data point to the next based on some reference point.

What is common cause variation?

Natural variation that occurs randomly within a predictable range and cannot be traced to a specific cause.

What is special cause variation?

Variation that occurs due to an assignable cause outside natural variation, such as people or machinery.

How is standard deviation used in quality control?

It quantifies the amount of variation or dispersion in a set of values.

What is the purpose of control charts in quality control?

To track a process and signal when it is getting out of control.

What are the two types of control charts?

Control charts for variables and control charts for attributes.

What do X-bar charts monitor?

The central tendency of a process.

What do R-charts monitor?

The variation within a process.

What is the significance of upper and lower control limits in control charts?

They indicate the range of normal variation; points outside these limits indicate assignable variation.

What is random variation?

Variation due to chance that is inherent in the design of the process.

How can random variation be reduced?

By using better design, materials, or equipment.

What is statistical process control?

A procedure to check if a process has changed in a way that would affect product quality.