6. Food Processing and Preservation Technologies

Introduction and Context

Food processing is the deliberate transformation of raw agricultural materials into foods that are safe, stable, convenient, palatable and economically valuable. Preservation is the control of physical, chemical and biological changes that would otherwise reduce food quality or make it unsafe. In hotel management, these technologies are not confined to factories. They influence purchasing, menu planning, storage, food cost, kitchen operations, waste reduction, regulatory compliance and guest satisfaction.

Fresh foods are biologically active systems. Enzymes continue to function after harvest, microorganisms may multiply, fats may oxidise, pigments may change and moisture may migrate between ingredients. Processing technologies intervene in these changes. The appropriate intervention depends on the characteristics of the food, the intended shelf life, distribution conditions, available equipment, capital, energy, labour, packaging and the quality expected by the customer.

No single preservation method is universally superior. Heat may provide excellent microbial safety but damage texture or flavour. Freezing generally retains nutritional value but requires an uninterrupted cold chain. Dehydration reduces water activity and transport weight but can produce shrinkage and undesirable texture. Emerging technologies such as high-pressure processing may preserve fresh-like quality, although they require specialised equipment and suitable packaging. Sound decisions therefore require comparison rather than simple preference.

Learning Objectives

After studying this chapter, the learner should be able to:

1. Explain the scientific basis of major food processing and preservation technologies.

2. Distinguish microbial control from quality preservation and relate both to food safety.

3. Compare thermal processing, chilling, freezing, dehydration, concentration, irradiation, modified-atmosphere packaging and high-pressure processing.

4. Apply hurdle technology principles to food-service and hospitality situations.

5. Evaluate technologies using safety, quality, cost, sustainability and operational criteria.

6. Identify regulatory, ethical, managerial and technological issues in preservation decisions.

7. Recommend an appropriate preservation system for a particular product or hotel operation.

The Preservation Problem: What Must Be Controlled?

The central scientific concept in preservation is the control of microbial growth and chemical or enzymatic deterioration. Microorganisms require suitable nutrients, water, temperature, pH, oxygen and time. Preservation removes or restricts one or more of these conditions. The measure most directly associated with microbial availability of water is water activity, expressed as aw. It is different from total moisture: two foods may contain similar moisture but make different proportions of that moisture available to microorganisms.

Temperature strongly affects reaction rates and microbial growth. Chilling slows growth but usually does not stop all microorganisms. Freezing converts water into ice and greatly reduces available liquid water, although most microorganisms are not necessarily killed. Thawing can therefore restore conditions for rapid growth. Acidity, measured by pH, is another important factor. Acid foods generally restrict many pathogens, but acid-tolerant yeasts, moulds and some bacteria remain relevant. Oxygen availability influences aerobic microorganisms, oxidative rancidity and pigment stability.

Preservation must also address enzymes naturally present in food. Blanching vegetables before freezing, for example, inactivates enzymes that would otherwise cause colour, flavour and texture deterioration. Packaging is not merely a container; it is part of the preservation system because it controls moisture transfer, oxygen exposure, light, contamination and mechanical damage.

Important terminology

A process lethality is the microbial inactivation achieved by a treatment. A thermal death time describes the time required at a specified temperature to destroy a defined microbial population, while the D-value is the time required for a one-logarithmic, or tenfold, reduction under specified conditions. The z-value is the temperature increase required to change the D-value by a factor of ten. These measures help process authorities design safe heat treatments.

A critical control point is a step at which control is essential to prevent, eliminate or reduce a food-safety hazard to an acceptable level. Shelf life is the period during which a food remains safe and meets defined quality specifications under stated storage conditions. Cold chain refers to the continuous maintenance of required low temperatures during storage, transport, display and service.

Thermal Processing: Reliable Safety Through Controlled Heat

Thermal processing uses heat to destroy or reduce microorganisms and inactivate enzymes. It includes blanching, pasteurisation, sterilisation, commercial sterilisation, cooking and hot filling. The required intensity depends on food acidity, viscosity, packaging, target organisms and desired shelf life.

Pasteurisation is a relatively mild heat treatment designed to destroy vegetative pathogens and reduce spoilage organisms while preserving sensory quality. Milk, liquid egg products, fruit beverages and some sauces may be pasteurised. Pasteurised foods normally require refrigeration because spores and some heat-resistant organisms can survive. Sterilisation and commercial sterilisation use more severe conditions. Commercially sterile foods are processed to achieve stability under normal unrefrigerated storage, although the objective is practical safety and stability rather than the absolute destruction of every microorganism.

Blanching is usually applied to vegetables before freezing or dehydration. Its principal purpose is enzyme inactivation, colour stabilisation and reduction of surface microorganisms, not complete preservation. Canning combines heat treatment with hermetic sealing. In low-acid canned foods, control of spore-forming pathogens is especially important, and scheduled processes must be validated according to product composition, container size and heat penetration.

Thermal treatment offers strong safety assurance, predictable processing and compatibility with large-scale production. Its disadvantages include nutrient losses, cooked flavours, softening, browning and energy consumption. The severity of treatment must be sufficient for safety but no greater than necessary for quality. In hotel kitchens, thermal preservation is seen in pasteurised sauces, cooked-and-chilled foods, sous-vide products, preserves and ready-to-eat meals. Vacuum cooking does not eliminate the need for validated time-temperature control; anaerobic conditions can create serious hazards if temperature management is inadequate.

Chilling and Freezing: Managing Temperature and Ice

Chilling usually stores foods above their freezing point, commonly within a product-specific refrigerated range. It slows microbial multiplication and chemical reactions without fundamentally changing the food structure. Its success depends on rapid cooling after cooking, correct storage temperature, hygienic handling, suitable packaging and avoidance of temperature abuse.

Rapid chilling is particularly important in institutional and hotel food production. Large containers of soup, curry or cooked rice cool slowly at the centre, allowing microorganisms to multiply. Shallow pans, portioning, blast chilling and monitored refrigeration reduce this risk. A chilled product remains perishable; refrigeration extends shelf life but does not make a food sterile.

Freezing preserves food by converting much of its water into ice. Rapid freezing produces smaller ice crystals, generally causing less cellular damage than slow freezing. Thawing should be controlled because exudate loss, texture deterioration and microbial growth may occur. Repeated freeze–thaw cycles are especially damaging. Freezer burn results from moisture migration and sublimation at the product surface; it is primarily a quality defect, although it indicates poor packaging or storage conditions.

Freezing is suitable for meat, seafood, vegetables, fruits, bakery products and prepared meals. It usually retains nutrients well, but texture-sensitive foods such as some leafy vegetables, cream-based preparations and high-water fruits may deteriorate. The capital and energy requirements of freezing, together with the need for a reliable cold chain, influence cost. In hospitality, portion-controlled frozen ingredients can reduce labour and waste, but operators must assess whether thawed quality meets the menu promise.

Dehydration and Concentration: Preservation by Removing Water

Dehydration removes water by evaporation, usually with heated air, vacuum, spray drying, drum drying or freeze-drying. By lowering water activity, it restricts the growth of most bacteria and many yeasts and moulds. Dehydrated products may be lightweight and convenient, but they can experience case hardening, colour loss, flavour changes, oxidation and rehydration problems.

Drying rate depends on temperature, air velocity, relative humidity, food composition, piece size and surface characteristics. Excessive temperature may cause browning or nutrient damage, whereas inadequate drying leaves sufficient water for spoilage. Packaging must prevent moisture uptake after drying. Dried herbs, spices, fruit, mushrooms, instant beverages and powdered ingredients illustrate common applications.

Freeze-drying first freezes the product and then removes ice by sublimation under vacuum. It can preserve shape, aroma and rehydration characteristics better than many conventional drying methods, but it is expensive and energy intensive. Spray drying is widely used for milk, coffee, flavourings and emulsions because liquid feed can be converted into powder rapidly.

Concentration removes part of the water from a liquid food but does not normally reduce water activity enough for complete preservation. Fruit concentrates, syrups, tomato products and condensed milk often require additional hurdles such as acidity, sugar, refrigeration or heat treatment. Concentration can reduce transport and storage costs, but excessive heating may damage volatile flavours and colour.

Chemical and Formulation-Based Preservation

Salt, sugar, organic acids, approved preservatives and fermentation can create conditions unfavourable to pathogens and spoilage organisms. Salt and sugar reduce water activity; acids lower pH; preservatives may inhibit specific groups of microorganisms. Their effectiveness depends on concentration, distribution, temperature and the food matrix.

Fermentation is a biological preservation process in which selected or naturally occurring microorganisms convert carbohydrates into acids, alcohol or other inhibitory metabolites. Yoghurt, cheese, pickles, sourdough and fermented beverages demonstrate how fermentation can improve safety, flavour and value. However, fermentation is not automatically safe: starter cultures, salt concentration, temperature, acidity and hygiene must be controlled.

Chemical preservatives must be legally permitted and used at authorised levels. Labels should accurately communicate their presence where required. A professional operator should never substitute excessive salt, sugar or acid for validated process control, particularly when vulnerable consumers may be exposed.

Irradiation: Ionising Energy as a Preservation Tool

Food irradiation exposes products to controlled ionising radiation. Depending on dose and application, it may inhibit sprouting, delay ripening, reduce insect infestation, eliminate parasites or reduce microbial populations. It can be applied to spices, certain fruits and vegetables, grains and some animal products under regulatory approval.

Irradiation does not make food radioactive. Nevertheless, it is a process requiring approved facilities, dose control, traceability, packaging compatibility and regulatory labelling. Its effects on quality depend on dose, food composition and oxygen conditions. It cannot compensate for poor hygiene after treatment, and irradiated food may still require refrigeration.

Public acceptance is influenced by communication and trust. Hospitality managers should provide accurate information rather than implying that irradiation is either inherently dangerous or a substitute for all other controls.

Modified-Atmosphere Packaging and Vacuum Packaging

Modified-atmosphere packaging (MAP) replaces or adjusts the air surrounding food, commonly using carbon dioxide, nitrogen and oxygen in carefully selected proportions. Reduced oxygen may slow oxidation and aerobic microbial growth, while carbon dioxide can inhibit certain spoilage organisms. Vacuum packaging removes much of the air without necessarily introducing a replacement gas.

MAP can preserve colour in fresh meat, extend the quality of prepared foods and reduce food waste. However, it does not sterilise the product. Reduced-oxygen conditions can favour anaerobic hazards if temperature and shelf life are poorly controlled. Gas composition changes during storage because microorganisms and food tissues consume or produce gases. Film permeability, seal integrity, headspace volume and storage temperature therefore require technical control.

For hotels, vacuum packaging can support central production, portion control and sous-vide cooking. Products must be labelled with production dates, use-by dates, storage requirements and reheating instructions. A visually attractive package is not evidence of safety; strict validated controls remain essential.

High-Pressure Processing and Other Non-Thermal Technologies

High-pressure processing (HPP) subjects packaged food, usually in a water-filled pressure vessel, to very high hydrostatic pressure for a specified time. Pressure is transmitted uniformly, so container shape has limited influence on treatment. HPP can inactivate many vegetative microorganisms while retaining fresh flavour, colour and certain nutrients better than severe heating. It is used for juices, dips, ready-to-eat meats, seafood and other suitable products.

HPP is less effective against bacterial spores unless combined with heat or other hurdles. It also requires pressure-resistant flexible packaging and substantial capital investment. Product formulation, pH, water activity and post-process contamination determine the final safety outcome.

Pulsed electric fields are used mainly for pumpable liquids and can disrupt microbial cells with limited heating. Ultrasound may assist extraction, cleaning or microbial control, while ultraviolet light can treat surfaces, air and transparent liquids. These methods are application-specific and should not be treated as universal replacements for thermal processing. Their suitability depends on penetration, product geometry, validation evidence and regulatory acceptance.

Hurdle Technology: Combining Moderate Controls

Hurdle technology uses several preservation factors, each insufficient or less desirable alone, in combination. Typical hurdles include low pH, reduced water activity, refrigeration, mild heat, preservatives, competitive cultures, packaging and limited oxygen. The combined system prevents microorganisms from adapting, growing or causing unacceptable deterioration.

For example, a chilled ready-to-eat sauce might use acidification, pasteurisation, hygienic filling, a sealed package and refrigerated storage. A fruit preserve may combine high soluble solids, acidity, heat treatment and a suitable container. The principle is not simply to add more treatments; it is to design complementary controls that provide safety while protecting quality and reducing cost.

A hurdle plan should identify hazards, define measurable limits, establish monitoring and corrective actions, and verify the system. Interactions can be complex. A small change in pH, salt, packaging or storage temperature may substantially alter shelf life. The system must therefore be validated for the actual recipe, process, equipment and distribution chain.

A Framework for Selecting a Preservation Technology

Technology selection should begin with the product and the intended use rather than with equipment availability. The following questions provide a practical decision framework:

• What hazards are present, and is the food ready to eat?
• What shelf life and distribution distance are required?
• Is the product acidic, low-acid, liquid, particulate, solid or emulsion-based?
• Which attributes—fresh flavour, crispness, colour, aroma or nutritional value—are essential?
• Can the operation maintain a reliable cold chain?
• What are the capital, labour, energy, packaging and maintenance costs?
• Is the required technology available at the hotel, through a supplier or through a contract processor?
• What regulations, labelling requirements and customer expectations apply?

A useful managerial comparison considers five dimensions: safety assurance, quality retention, operational feasibility, total cost and sustainability. Total cost includes purchase price, energy, water, labour, waste, maintenance, packaging, transport and the cost of product failure. The cheapest treatment per unit may not be the least costly system if it produces high waste or frequent quality complaints.

Practical and Professional Applications in Hospitality

Hotels use preservation technologies across procurement, production and service. Central kitchens may cook, blast chill, portion, package and distribute meals to outlets. Restaurants may use vacuum-packed ingredients, frozen seafood, dried spices, concentrated stocks and fermented products. Banqueting operations depend on accurate production planning because excess food may become a safety and financial liability.

Managers should establish product specifications that include receiving temperature, packaging condition, use-by period, storage location, rotation method and preparation instructions. Employees require training in thermometer use, cooling procedures, thawing, allergen control, package integrity and documentation. Digital temperature loggers and cloud-based monitoring can alert managers to deviations, but technology does not replace corrective action or competent supervision.

Sustainability decisions require balance. Freezing and refrigeration consume energy, while dehydration reduces transport weight but may require substantial heat. Packaging can extend shelf life and prevent waste, yet multilayer materials may be difficult to recycle. A life-cycle perspective is more useful than judging a technology solely by its packaging or energy use.

Illustrative Case Study: Extending the Shelf Life of a Hotel’s Fresh Sauce

Background

A 180-room hotel produces a refrigerated herb-and-yoghurt sauce for restaurants and banquets. The sauce has a fresh appearance and flavour but currently remains acceptable for only three days. Approximately 12 percent of production is discarded because demand fluctuates.

Situation and problem

The executive chef proposes freezing the sauce, but sensory trials show separation after thawing. The purchasing manager suggests adding more preservatives, while the food-safety manager is concerned about relying on formulation changes without validation. The hotel seeks a solution that improves shelf life without compromising the fresh quality promised on the menu.

Analysis

The sauce is a ready-to-eat, high-moisture product. Its risks include contamination after mixing, growth during refrigerated storage and quality loss through oxidation or phase separation. Freezing is unsuitable unless the formulation is redesigned. A severe heat treatment would damage the yoghurt structure and herbs. Vacuum packaging may reduce oxygen but does not by itself control all microbial hazards.

The team measures pH, evaluates ingredient quality, reviews hygienic zoning and examines the cooling and filling process. They identify that the sauce is filled manually into large containers, creating prolonged exposure and slow cooling. The main opportunity is therefore process control rather than a single new technology.

Approach and solution

The hotel adopts a hurdle strategy: validated acidification within the approved product specification, pasteurisation of the base before addition of heat-sensitive herbs, rapid chilling, hygienic addition of herbs, portion filling in sealed containers, refrigerated storage with continuous temperature monitoring, and a conservative use-by period established through shelf-life testing. A small amount of approved antioxidant is considered only after regulatory and sensory review. The product is labelled with batch identification and handling instructions.

Outcome

In this illustrative case, the combined system extends acceptable refrigerated life, reduces exposure during filling and lowers waste without changing the menu identity. The final shelf life is not assumed from laboratory results alone; it is confirmed through microbiological, chemical and sensory studies under intended storage conditions.

Learning points

The case demonstrates that preservation is a system. A new machine would not correct poor hygiene or slow cooling. Hurdles must be measurable, validated and matched to the product. Quality objectives, food safety, cost and customer expectations should be evaluated together.

Risks, Limitations and Common Errors

Common failures include confusing refrigeration with safety, estimating cooling time by container size alone, refreezing thawed foods without evaluation, ignoring post-process contamination, using unsuitable packaging and assigning shelf life without evidence. Another error is treating a laboratory process as automatically transferable to commercial production. Equipment loading, product viscosity, container geometry and operator practice can change process performance.

Thermal processes may be under-processed or over-processed. Freezing systems may suffer from temperature fluctuations. Dehydrated foods may reabsorb moisture. MAP products may appear fresh while hazardous microorganisms increase. Irradiation and HPP may be technically effective but economically unsuitable for a small operation. Every technology has a boundary of safe application.

Governance, Regulation and Professional Ethics

Food businesses are responsible for supplying safe food and complying with applicable food laws, standards, labelling rules and inspection requirements. HACCP-based systems should identify biological, chemical and physical hazards and establish verification. Records must be accurate enough to demonstrate that critical controls were monitored.

Ethical practice requires truthful communication. A hotel should not describe a highly processed product as “fresh” in a way that misleads guests, nor should it conceal relevant allergen, irradiation or preservative information where disclosure is required. Claims such as “natural,” “chemical-free” or “preservative-free” must be interpreted carefully and supported by evidence. Supplier audits, traceability and recall procedures are central elements of responsible management.

Emerging Developments

Current development is directed toward milder processing, precision control and integrated systems. Improved sensors can monitor temperature, pressure, moisture and gas composition in real time. Predictive microbiology and data analytics can support shelf-life estimation, although models require validation against actual products. Automation can improve portioning, sealing and traceability in central kitchens.

Research is also exploring pulsed light, cold plasma, advanced membrane concentration, edible coatings, intelligent packaging and combinations of non-thermal technologies. The important managerial trend is convergence: processing, packaging, refrigeration, data systems and supply-chain design are increasingly treated as one preservation platform rather than separate activities.

Best-Practice Principles

1. Begin with hazard analysis and product requirements.

2. Use validated processes rather than assumed time and temperature rules.

3. Treat packaging and cold-chain management as part of preservation.

4. Monitor critical limits and document deviations.

5. Test both safety and sensory shelf life.

6. Train staff in the reasons behind procedures, not only the procedures themselves.

7. Select the least severe process that achieves the required safety and stability.

8. Review energy, packaging, waste and total cost before investment.

9. Revalidate processes when recipes, equipment, package size or distribution conditions change.

10. Communicate honestly with guests, regulators and business partners.

Chapter Summary

Food preservation controls microbial growth, enzymes, oxidation, moisture migration and other causes of deterioration. Thermal processing offers dependable microbial reduction but may affect fresh quality. Chilling slows deterioration, whereas freezing provides longer stability through ice formation but requires an uninterrupted cold chain. Dehydration and concentration reduce available water and transport weight, while irradiation, MAP, vacuum packaging and HPP provide more specialised controls. Fermentation and formulation-based methods use acidity, salt, sugar, cultures or approved preservatives.

Hurdle technology combines moderate controls to achieve safety and quality with less severe treatment. Selection should be based on hazards, product properties, desired shelf life, sensory objectives, cost, sustainability, regulation and operational capability. In hospitality, preservation is a managed system linking procurement, preparation, packaging, storage, distribution, monitoring and service. Validated processes, accurate records, trained employees and truthful communication are essential to professional practice.

Key Terms

Water activity: The availability of water in a food for microbial growth and chemical reactions.

Pasteurisation: A controlled heat treatment that destroys pathogens and reduces spoilage organisms without achieving commercial sterility.

Commercial sterility: A condition in which a processed food is stable and safe under specified storage conditions.

Blanching: A brief heat treatment, commonly used to inactivate enzymes before freezing or drying.

D-value: Time required at a specified condition to achieve a tenfold microbial reduction.

z-value: Temperature increase required to change a microorganism’s D-value tenfold.

Cold chain: Continuous maintenance of required low temperatures during handling and distribution.

Freezer burn: Surface quality deterioration caused by moisture loss and sublimation during frozen storage.

Dehydration: Removal of water from food, generally by evaporation.

Concentration: Partial removal of water from a liquid food.

Fermentation: Microbial conversion of food components into acids, alcohols or other products that can inhibit competitors and alter food quality.

Irradiation: Treatment of food with controlled ionising radiation.

Modified-atmosphere packaging: Packaging in which the surrounding gas composition is changed to influence shelf life.

Vacuum packaging: Removal of much of the air from a sealed package.

High-pressure processing: Preservation using high hydrostatic pressure, usually in a water-filled vessel.

Hurdle technology: Use of several complementary preservation factors to inhibit microorganisms and deterioration.

Shelf life: Period during which food remains safe and meets specified quality requirements.

Critical control point: A step where control is essential to prevent or reduce a food-safety hazard.

Validation: Evidence that a process is capable of achieving its intended safety or quality outcome.

Traceability: Ability to follow a food, ingredient or batch through specified stages of production and distribution.

Review Questions

Short Answer Questions

1. Why is water activity more useful than moisture content alone when assessing microbial growth?

2. Distinguish pasteurisation from commercial sterilisation.

3. Why is rapid cooling important in hotel food production?

4. What is the principal purpose of blanching before freezing vegetables?

5. Define hurdle technology and provide one example.

Long Answer Questions

1. Compare chilling and freezing with respect to mechanism, quality, safety, cost and hospitality applications.

2. Explain the advantages and limitations of thermal processing, dehydration and concentration.

3. Discuss the operating principles and food-safety implications of MAP and vacuum packaging.

4. Examine HPP and irradiation as alternatives or complements to conventional processing.

5. Develop a preservation-selection framework for a hotel central kitchen.

Analytical / Application Questions

1. A hotel wants to distribute a chilled ready-to-eat soup to three properties. Recommend a preservation and monitoring system, explaining the hurdles and validation evidence required.

2. A frozen fruit dessert develops large ice crystals and severe drip loss. Analyse the likely causes and propose corrective actions.

3. A chef proposes vacuum-packing a cooked low-acid food for a seven-day refrigerated shelf life. Evaluate the proposal from safety, quality, regulatory and managerial perspectives.

22. Multiple Choice Questions with Answers

Question 1

Which preservation factor most directly restricts microbial growth by reducing the water available to microorganisms?

A. Water activity reduction

B. Increased oxygen concentration

C. Larger package size

D. Higher storage humidity

Correct Answer: A. Water activity reduction

Question 2

The principal purpose of blanching vegetables before freezing is to:

A. Sterilise the vegetables completely

B. Inactivate enzymes that cause quality deterioration

C. Increase their water activity

D. Create a modified atmosphere

Correct Answer: B. Inactivate enzymes that cause quality deterioration

Question 3

Why does rapid freezing generally produce better texture than slow freezing?

A. It destroys all microorganisms

B. It produces smaller ice crystals and less cellular damage

C. It increases oxygen diffusion

D. It removes all water from the product

Correct Answer: B. It produces smaller ice crystals and less cellular damage

Question 4

A pasteurised food normally requires refrigeration because pasteurisation:

A. Destroys every bacterial spore

B. Does not eliminate all microorganisms capable of later growth

C. Increases the product’s water activity

D. Removes the need for hygienic handling

Correct Answer: B. Does not eliminate all microorganisms capable of later growth

Question 5

Which combination best illustrates hurdle technology?

A. Only increasing package size

B. Acidification, mild heat, hygienic filling and refrigeration

C. Leaving food at room temperature in a sealed container

D. Using a decorative label with no process change

Correct Answer: B. Acidification, mild heat, hygienic filling and refrigeration

Question 6

What is a significant safety concern with reduced-oxygen packaging?

A. It always causes immediate freezing

B. It may favour anaerobic hazards if time and temperature are poorly controlled

C. It sterilises the product without heat

D. It prevents all chemical reactions

Correct Answer: B. It may favour anaerobic hazards if time and temperature are poorly controlled

Question 7

Which statement about high-pressure processing is most accurate?

A. It is equally effective against all bacterial spores

B. It can retain fresh-like qualities but requires suitable equipment and packaging

C. It makes products radioactive

D. It is applicable only to dry powders

Correct Answer: B. It can retain fresh-like qualities but requires suitable equipment and packaging

Question 8

A hotel is selecting between freezing and dehydration. Which factor most strongly favours dehydration?

A. The need for a lightweight product with reduced transport volume

B. A requirement to preserve the original fresh texture of leafy vegetables

C. The absence of any packaging requirement

D. The intention to eliminate all post-process hazards

Correct Answer: A. The need for a lightweight product with reduced transport volume

Question 9

Which measure describes the time required for a tenfold reduction in a microbial population under specified conditions?

A. z-value

B. D-value

C. pH value

D. Shelf-life value

Correct Answer: B. D-value

Question 10

A hotel’s new sauce process includes acidification, pasteurisation, rapid chilling, sealed filling and refrigerated storage. This design demonstrates that:

A. One severe treatment is always unnecessary and unsafe

B. Several validated moderate controls can work together as a preservation system

C. Packaging replaces the need for temperature control

D. Acid foods never require microbiological assessment

Correct Answer: B. Several validated moderate controls can work together as a preservation system