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WBBSE Madhyamik Food Processing (Vocational) study materials
WBBSE Madhyamik Food Processing (Vocational) study resources

WBBSE Madhyamik Food Processing (Vocational) practice questions

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Question 1Introduction to Food Processing and Food Science Basics

In food processing, which of the following is the best example of a primary processing operation applied to raw agricultural produce?

  1. Preparing a ready-to-eat curry in a retort pouch
  2. Cleaning and grading harvested paddy before milling Correct answer.
  3. Baking bread from refined wheat flour
  4. Formulating a vitamin-fortified breakfast cereal

Explanation

Primary processing covers the first steps that turn harvested or slaughtered raw material into a stable, transportable form, such as cleaning, grading, sorting, drying and milling. Baking, retort cooking and fortification happen later, after the raw material has already been converted into an ingredient or food. So only cleaning and grading paddy is a primary operation.

Question 2Introduction to Food Processing and Food Science Basics

Which statement correctly distinguishes food processing from food preservation?

  1. Processing and preservation are exactly the same set of operations
  2. Preservation changes raw material into a food product, while processing only extends shelf life
  3. Processing applies only to animal foods, while preservation applies only to plant foods
  4. Processing changes raw material into a food product, while preservation extends its usable life Correct answer.

Explanation

Processing refers to the set of operations that convert raw material into a food product with desired form, texture or safety, while preservation specifically aims to slow spoilage and extend shelf life. The two overlap because many processing steps also preserve, but they are not identical concepts. The remaining options reverse the definitions or invent a plant-versus-animal split that does not exist.

Question 3Introduction to Food Processing and Food Science Basics

A home-scale food unit dries fish in the open sun on bamboo mats. Which main purpose of food processing does this step most directly serve?

  1. Improving the protein digestibility of the fish
  2. Adding essential micronutrients to the fish
  3. Increasing the water activity of the product
  4. Preserving the fish by lowering its moisture content Correct answer.

Explanation

Sun drying removes water, which lowers water activity and slows the growth of spoilage microorganisms and enzymes, so it is essentially a preservation step. It does not add nutrients, and it generally does not raise water activity. Improved protein digestibility is not the main purpose of simple drying.

Question 4Introduction to Food Processing and Food Science Basics

In food science, what does the term 'water activity' (a_w) measure?

  1. The volume of water absorbed by a dry food during soaking
  2. The total mass of water present in a food sample
  3. The ratio of free water vapour pressure in a food to that of pure water at the same temperature Correct answer.
  4. The temperature at which water inside a food begins to boil

Explanation

Water activity is defined as the vapour pressure of water in the food divided by the vapour pressure of pure water at the same temperature, so it measures the availability of water rather than its total amount. Microorganisms need available water, which is why a_w predicts microbial stability better than moisture content. Total mass, boiling temperature and soaking volume are unrelated quantities.

Question 5Introduction to Food Processing and Food Science Basics

Which of the following is a correct statement about the macronutrient composition of foods?

  1. Carbohydrates, proteins and fats are energy-yielding macronutrients Correct answer.
  2. Dietary fibre is a mineral that provides no energy
  3. Vitamins and minerals are the main energy-yielding macronutrients
  4. Water is classified as a macronutrient because it is needed in large amounts

Explanation

Carbohydrates, proteins and fats supply energy and are therefore called energy-yielding macronutrients, along with water being needed in bulk but not as an energy source. Vitamins and minerals are micronutrients required in small amounts and do not yield energy. Fibre is a carbohydrate component, not a mineral.

Question 6Introduction to Food Processing and Food Science Basics

Which of the following is the most appropriate example of a unit operation in food processing?

  1. Manufacturing a complete ready-to-eat meal kit
  2. Designing a food factory layout
  3. Distributing packaged foods to retail outlets
  4. Size reduction of grains by grinding Correct answer.

Explanation

A unit operation is a single, identifiable physical step such as grinding, sieving, mixing, heating or freezing that can be combined with others to build a process. Grinding grains is a discrete physical operation. Making a whole meal kit, distributing products and designing a layout are broader activities, not individual unit operations.

Question 7Introduction to Food Processing and Food Science Basics

A processor wants to reduce spoilage of bottled mango juice by destroying vegetative pathogens already present in the juice. Which processing approach is most directly suited?

  1. Chilling the juice to 4 degrees Celsius and storing it
  2. Adding more sugar to the juice
  3. Packaging the juice in clear glass bottles
  4. Applying a controlled heat treatment such as pasteurisation Correct answer.

Explanation

Pasteurisation uses a controlled heat treatment to destroy vegetative pathogens and spoilage organisms in a liquid food such as juice. Sugar addition and refrigeration slow but do not destroy organisms already present, and clear glass packaging offers no microbial kill step. The objective stated is destruction of existing vegetative pathogens, so a heat treatment is the direct answer.

Question 8Introduction to Food Processing and Food Science Basics

Which change in a food is mainly caused by the Maillard reaction during heating?

  1. Loss of vitamin C through oxidation in an acidic medium
  2. Separation of oil and water in an unstable emulsion
  3. Development of brown colour and roasted flavour when sugars react with amino groups Correct answer.
  4. Formation of ice crystals during slow freezing

Explanation

The Maillard reaction is a non-enzymatic browning reaction in which reducing sugars condense with amino groups of proteins or amino acids, producing brown pigments and characteristic roasted or baked flavours. It requires heat and low moisture, as in baking and frying. Vitamin loss, ice crystal formation and emulsion breakdown are different phenomena.

Question 9Introduction to Food Processing and Food Science Basics

Enzymatic browning of cut apples and potatoes is best controlled by which measure?

  1. Exposing the cut surfaces to open air for a long time
  2. Blanching or treating with ascorbic acid or citric acid solution Correct answer.
  3. Storing the cut pieces in a warm, humid chamber
  4. Increasing the pH strongly with lime water

Explanation

Enzymatic browning results from polyphenol oxidase acting on phenolic compounds when cells are damaged and oxygen is present. Heat from blanching denatures the enzyme, while ascorbic acid reduces the quinone intermediates and citric acid lowers pH to slow the enzyme. Warm humid storage, alkaline conditions and prolonged air exposure all favour browning.

Question 10Introduction to Food Processing and Food Science Basics

Which statement about the role of pH in food spoilage and preservation is correct?

  1. pH has no effect on the activity of preservatives
  2. Lowering pH always increases the heat resistance of bacterial spores
  3. All microorganisms grow fastest at pH 2
  4. Most bacteria grow best near neutral pH, so acidification can inhibit them Correct answer.

Explanation

Most bacteria, including many pathogens, grow best around neutral pH, so lowering pH by fermentation or acid addition restricts their growth. Very few organisms tolerate pH near 2, and acidification generally reduces rather than increases heat resistance. pH also strongly affects the effectiveness of preservatives such as benzoates and sulphites.

Question 11Introduction to Food Processing and Food Science Basics

During slow freezing of a food, which change is typically observed compared with rapid freezing?

  1. Water activity of the frozen product becomes zero
  2. Larger ice crystals form outside the cells and damage texture Correct answer.
  3. Smaller ice crystals form within the cells
  4. No ice crystals form at all

Explanation

Slow freezing allows ice crystals to grow large, and these crystals tend to form in extracellular spaces, rupturing cell walls and causing drip loss and poor texture on thawing. Rapid freezing produces many small crystals distributed more evenly. Ice crystals certainly form, and water activity does not fall to zero merely because the food is frozen.

Question 12Introduction to Food Processing and Food Science Basics

Which of the following correctly describes the principle of canning as a preservation method?

  1. The food is exposed to ultraviolet light after sealing to sterilise the contents
  2. The food is stored under vacuum without any heat treatment
  3. The food is kept sweet enough that no microorganism can ever grow
  4. The food is sealed in a container and given a heat treatment sufficient to inactivate microorganisms Correct answer.

Explanation

Canning relies on sealing food in an airtight container and applying a heat process sufficient to destroy the target microorganisms and inactivate enzymes, so that the sealed product remains stable. UV light does not penetrate food and is not the basis of canning. High sugar and vacuum alone are not the canning principle.

Question 13Introduction to Food Processing and Food Science Basics

A food technologist measures the moisture content of a biscuit as 4 percent and its water activity as 0.35. What is the most reasonable conclusion?

  1. The biscuit has high water activity despite its low moisture
  2. The biscuit must be refrigerated to prevent mould growth
  3. The biscuit is likely to support rapid growth of most bacteria
  4. The biscuit is likely to be microbiologically stable because available water is low Correct answer.

Explanation

Most bacteria require water activity above about 0.90 for growth, and many moulds need above about 0.70, so a value of 0.35 indicates very little available water. This explains why dry biscuits are shelf-stable without refrigeration. The low moisture value is consistent with the low water activity, not in conflict with it.

Question 14Introduction to Food Processing and Food Science Basics

Which of the following best explains why blanching vegetables before freezing improves product quality?

  1. It adds a protective sugar coating to each piece
  2. It inactivates enzymes that would otherwise cause off-flavours and colour loss during storage Correct answer.
  3. It increases the water content so the tissue freezes more evenly
  4. It sterilises the vegetables so that no microorganisms remain

Explanation

Blanching is a short heat treatment that denatures enzymes such as peroxidase and polyphenol oxidase, which would otherwise cause off-flavours, colour changes and nutrient loss during frozen storage. It does not sterilise the product, since freezing foods are not commercially sterile. It also does not add water or sugar coatings.

Question 15Introduction to Food Processing and Food Science Basics

Which statement about food additives and their functions is correct?

  1. Preservatives inhibit microbial growth, while antioxidants delay oxidative rancidity Correct answer.
  2. Preservatives add colour, while antioxidants add sweetness
  3. Antioxidants inhibit microbial growth, while preservatives delay rancidity
  4. Emulsifiers are used mainly to increase the protein content of foods

Explanation

Preservatives such as sorbates and benzoates inhibit microbial growth, whereas antioxidants such as BHA or ascorbic acid delay oxidation of fats and pigments. Colourants and sweeteners are separate functional classes. Emulsifiers stabilise mixtures of oil and water and do not raise protein content.

Question 16Introduction to Food Processing and Food Science Basics

Which of the following correctly pairs a foodborne pathogen with a typical associated food source?

  1. Saccharomyces cerevisiae with raw eggs
  2. Trichinella spiralis with dried spices
  3. Lactobacillus bulgaricus with raw poultry
  4. Clostridium botulinum with low-acid canned foods that received insufficient heat processing Correct answer.

Explanation

Clostridium botulinum forms heat-resistant spores that can survive inadequate canning of low-acid foods and then produce toxin in the anaerobic sealed can. Lactobacillus bulgaricus and Saccharomyces cerevisiae are useful fermentation organisms, not poultry or egg pathogens. Trichinella spiralis is a parasite associated with undercooked pork, not dried spices.

Question 17Introduction to Food Processing and Food Science Basics

A small unit produces a fruit beverage and wants to compare two preservation options: pasteurisation at 90 degrees Celsius for 30 seconds, or storage at 4 degrees Celsius without heat treatment. Which reasoning is most sound?

  1. Both options give identical shelf life because temperature is the only factor
  2. Chilling alone is always superior because heat damages nutrients
  3. Pasteurisation destroys vegetative microorganisms and inactivates enzymes, giving a longer shelf life than chilling alone Correct answer.
  4. Neither option affects microbial growth because the beverage is acidic

Explanation

Pasteurisation at 90 degrees Celsius for 30 seconds destroys vegetative microorganisms and inactivates enzymes, so the product can be stored longer, while chilling only slows growth and requires an unbroken cold chain. Heat does cause some nutrient loss, but that does not make chilling always superior. The two options do not give identical shelf life, and acidity affects but does not eliminate microbial growth.

Question 18Introduction to Food Processing and Food Science Basics

In an emulsion such as mayonnaise, which mechanism best explains the role of an emulsifier?

  1. It increases the surface tension between oil and water
  2. It lowers interfacial tension and forms a film around droplets to prevent coalescence Correct answer.
  3. It removes all water from the system so that no droplets remain
  4. It raises the density of oil so that oil droplets sink and separate

Explanation

An emulsifier is surface-active: it lowers the interfacial tension between oil and water and forms a protective film around dispersed droplets, slowing coalescence and keeping the emulsion stable. Raising density, removing water or raising surface tension would all promote rather than prevent separation.

Question 19Introduction to Food Processing and Food Science Basics

A processor compares two drying methods for a heat-sensitive fruit pulp: hot-air drying at 80 degrees Celsius and freeze drying. Which conclusion is most defensible?

  1. Both methods give identical nutrient retention because water is removed in both
  2. Freeze drying better retains heat-sensitive nutrients and original structure but costs more Correct answer.
  3. Hot-air drying better retains heat-sensitive vitamins and the porous structure
  4. Freeze drying causes greater thermal degradation because it uses higher temperatures

Explanation

Freeze drying removes water by sublimation under vacuum at low temperature, so heat-sensitive vitamins and the porous structure are better preserved, but the equipment and energy costs are higher. Hot-air drying at 80 degrees Celsius exposes the pulp to heat that degrades sensitive nutrients and causes shrinkage. Nutrient retention is therefore not identical, and freeze drying does not use higher temperatures.

Question 20Introduction to Food Processing and Food Science Basics

Which statement correctly explains why a food with a lower pH generally requires a milder heat process to achieve commercial sterility?

  1. Acid conditions make the food thicker, which slows heat penetration
  2. Acid conditions sensitise microbial cells and spores to heat, so a lower heat dose is needed Correct answer.
  3. Acid conditions remove all microorganisms before heating begins
  4. Acid conditions increase the heat resistance of all spores

Explanation

Lower pH increases the heat sensitivity of microorganisms, so acid or acidified foods can be made commercially sterile with a milder heat process than low-acid foods. This is why low-acid canned foods, which support Clostridium botulinum, require a much more severe process. Acid does not thicken the food in a way that slows heat penetration, increase spore heat resistance, or remove organisms before heating.

Question 21Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

In wheat grain structure, which layer is rich in cellulose and gives protection to the grain?

  1. Bran Correct answer.
  2. Germ
  3. Endosperm
  4. Aleurone layer

Explanation

The bran is the outer protective covering of the wheat grain and is made up largely of cellulose and hemicellulose along with some minerals. It protects the inner endosperm and germ and is removed during milling to produce maida.

Question 22Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which cereal is commonly parboiled before milling to improve its nutritional quality and reduce breakage?

  1. Maize
  2. Paddy rice Correct answer.
  3. Wheat
  4. Barley

Explanation

Parboiling involves soaking, steaming and drying paddy before milling, which drives vitamins and minerals from the bran into the endosperm and hardens the grain. This reduces breakage during milling and retains more thiamine in the polished rice.

Question 23Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

The protein fraction of pulses that is soluble in water and is important for foaming and gel formation is:

  1. Glutelin
  2. Albumin Correct answer.
  3. Prolamin
  4. Globulin

Explanation

Pulse albumins are water-soluble proteins that contribute to foaming and gel-forming behaviour, while globulins are salt-soluble and form the major storage protein. Glutelins and prolamins are the main cereal storage proteins rather than the water-soluble pulse fraction.

Question 24Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

A processor wants to reduce the anti-nutritional factor trypsin inhibitor in soybean before using it in food. Which treatment is most effective?

  1. Adequate moist heat treatment Correct answer.
  2. Adding sodium chloride
  3. Dry storage at room temperature
  4. Soaking in cold water only

Explanation

Trypsin inhibitor in soybean is a heat-labile protein, so adequate moist heating such as boiling or steaming denatures it and improves protein digestibility. Cold soaking, dry storage or salting does not destroy the inhibitor effectively.

Question 25Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

In fruit and vegetable processing, the enzyme mainly responsible for enzymatic browning of cut surfaces is:

  1. Pectin methylesterase
  2. Amylase
  3. Polyphenol oxidase Correct answer.
  4. Lipase

Explanation

Polyphenol oxidase catalyses oxidation of phenolic compounds to quinones, which polymerise into brown pigments when tissue is cut and exposed to air. Blanching or use of ascorbic acid and citric acid is used to control this reaction.

Question 26Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which grading characteristic is most directly used to classify mangoes for table use rather than for processing?

  1. Fibre length of the stem
  2. Starch content of the stone
  3. Oil content of the peel
  4. Firmness, skin colour and freedom from blemishes Correct answer.

Explanation

Table mangoes are graded on external quality attributes such as size, firmness, skin colour, shape and absence of blemishes and decay. These visible characters guide market grading, whereas processing quality depends more on pulp yield, total soluble solids and acidity.

Question 27Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

The chief storage polysaccharide of potato tubers that influences chip texture and oil absorption is:

  1. Cellulose
  2. Starch Correct answer.
  3. Inulin
  4. Pectin

Explanation

Potato tuber dry matter is dominated by starch, and its content and granule behaviour affect texture, frying behaviour and oil uptake in chips. High dry matter with suitable starch gives crisp, less oily chips.

Question 28Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

A pulse sample shows hard-to-cook defect. Which storage condition is most commonly associated with this defect?

  1. Storage in the dark at low humidity
  2. Vacuum packaging at low temperature
  3. High humidity and warm temperature during storage Correct answer.
  4. Low humidity and cold storage

Explanation

The hard-to-cook defect develops when pulses are stored under warm, humid conditions, which promotes toughening of the seed coat and reduced water uptake during cooking. Cool, dry storage helps preserve normal cooking quality.

Question 29Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which statement correctly describes the difference between whole grain and refined cereal flour in terms of composition?

  1. Whole grain flour has no endosperm fraction
  2. Both contain identical ash content because milling does not change composition
  3. Whole grain flour retains bran and germ, giving more fibre and minerals Correct answer.
  4. Refined flour contains more bran and germ than whole grain flour

Explanation

Whole grain flour is milled from the entire kernel, so it retains bran and germ and therefore more dietary fibre, minerals and B vitamins. Refined flour consists mainly of endosperm and has lower fibre and ash.

Question 30Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

During blanching of green vegetables before freezing, the main purpose of the treatment is to:

  1. Increase the water content of tissue
  2. Promote microbial growth for fermentation
  3. Inactivate enzymes that cause off-flavour and colour loss Correct answer.
  4. Increase the starch content of the tissue

Explanation

Blanching uses hot water or steam to denature enzymes such as peroxidase and polyphenol oxidase that would otherwise cause off-flavours, browning and loss of green colour during frozen storage. It also helps remove surface air and some microorganisms.

Question 31Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which of the following is a characteristic feature of cereal prolamins?

  1. They are soluble only in strong alkali
  2. They are soluble in non-polar organic solvents
  3. They are soluble in aqueous alcohol solutions Correct answer.
  4. They are soluble in water and dilute salt solutions

Explanation

Prolamins such as gliadin in wheat and zein in maize are soluble in aqueous alcohol solutions and are rich in proline and glutamine. This solubility is used in the classical Osborne protein classification.

Question 32Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

A fruit juice processor observes loss of cloudiness and settling in stored juice. Which enzyme is chiefly involved in this defect?

  1. Pectin methylesterase Correct answer.
  2. Catalase
  3. Lipoxygenase
  4. Invertase

Explanation

Pectin methylesterase de-esterifies pectin, and the resulting low-methoxyl pectin can interact with calcium and coagulate, causing cloud loss and sediment in juices. Heat treatment is used to inactivate the enzyme.

Question 33Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which pulse is a major source of the sulphur-containing amino acid methionine relative to cereals, making the cereal-pulse combination nutritionally valuable?

  1. Soybean Correct answer.
  2. Black gram
  3. Bengal gram
  4. Lentil

Explanation

Soybean has a comparatively high protein content with a better methionine balance than most other pulses, while cereals are limiting in lysine. Combining cereals with soybean or other pulses improves the overall amino acid profile.

Question 34Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

In a cereal-based breakfast product, which change is expected when whole wheat flour replaces refined flour at the same moisture?

  1. Lower water absorption and brighter colour
  2. Higher fat content with lighter colour
  3. Higher water absorption and darker colour Correct answer.
  4. No change in water absorption

Explanation

Whole wheat flour contains bran particles that absorb more water and contain pigments, so dough water absorption rises and the product becomes darker with a bran-speckled appearance. Refined flour gives a lighter, lower-absorption dough.

Question 35Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which unit operation is most suitable for removing stones and dirt from a batch of pulses before milling?

  1. Roasting
  2. Destoning and washing Correct answer.
  3. Milling
  4. Fermentation

Explanation

Destoners use differences in density and size to separate heavy stones from pulses, and washing removes adhering soil and dust. Cleaning by destoning and washing is done before any milling or further processing.

Question 36Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which factor most strongly determines the total soluble solids content used as a maturity index in citrus fruits?

  1. Moisture content of the seed
  2. Amount of reducing sugars and organic acids Correct answer.
  3. Length of the fruit stalk
  4. Content of cellulose in the peel

Explanation

Total soluble solids in citrus juice are mainly sugars and organic acids, and the sugar-to-acid ratio is a standard maturity index. Peel cellulose, stalk length and seed moisture do not determine TSS.

Question 37Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which cereal is traditionally malted for use in brewing and in malt-based foods because of its high diastatic power?

  1. Rice
  2. Oats
  3. Barley Correct answer.
  4. Sorghum

Explanation

Barley germinates readily and produces high levels of amylase enzymes, giving strong diastatic power for converting starch to fermentable sugars during malting and mashing. This makes it the preferred brewing cereal.

Question 38Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

A vegetable processor wants to preserve the green colour of peas during canning. Which practice helps achieve this?

  1. Short blanch and avoidance of excessive acid in the brine Correct answer.
  2. Prolonged heating in an acidic medium
  3. Addition of copper salts to the brine
  4. Storage of the canned product at high temperature

Explanation

Chlorophyll is converted to brown pheophytin by heat and acid, so a short blanch and a brine of controlled pH help retain the green colour. Excessive heating and acidity accelerate the colour loss.

Question 39Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which property of wheat gluten is responsible for the elasticity of bread dough?

  1. Glutenin fraction providing elasticity Correct answer.
  2. Bran fibre content
  3. Albumin fraction providing foam
  4. Starch granule swelling

Explanation

Glutenin forms large, extensible networks that give dough its elastic and cohesive character, while gliadin contributes extensibility and viscosity. Together they form the viscoelastic gluten network that traps gas in bread dough.

Question 40Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which of the following best explains why pulses are soaked before cooking?

  1. Soaking destroys all protein in the seed
  2. Soaking increases the fat content of the seed
  3. Soaking increases the starch content of the seed
  4. Soaking softens the seed coat and reduces cooking time Correct answer.

Explanation

Soaking allows water to penetrate the seed coat and hydrate the cotyledons, which softens the tissue and shortens cooking time. It also leaches some oligosaccharides and antinutrients, improving digestibility.

Question 41Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

A batch of bananas is stored at low temperature and the peel blackens while the pulp remains hard. This disorder is best described as:

  1. Mechanical injury
  2. Chilling injury Correct answer.
  3. Freezing injury
  4. Sunburn

Explanation

Bananas are chilling-sensitive tropical fruits, and storage below about 12 to 13 degrees Celsius causes chilling injury with peel blackening, surface pitting and failure to ripen normally. The pulp may remain hard while the peel darkens.

Question 42Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which statement about the aleurone layer of a cereal grain is correct?

  1. It is a single layer of protein-rich cells beneath the bran Correct answer.
  2. It is the starchy storage tissue of the endosperm
  3. It is the outermost husk and contains mainly silica
  4. It is the embryo of the grain

Explanation

The aleurone layer lies just inside the bran and consists of thick-walled cells rich in protein, vitamins and minerals. In milling it is largely removed with the bran, which is why highly refined flour loses these nutrients.

Question 43Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

In the processing of tomato into paste, which quality attribute is most important for obtaining a thick product with good yield?

  1. High starch content of the pulp
  2. High cellulose content of the skin
  3. High seed oil content
  4. High soluble solids and high pectin content Correct answer.

Explanation

Tomato paste concentration depends on the soluble solids of the juice, and pectin contributes viscosity and consistency. Varieties with high soluble solids and suitable pectin give better yield and thicker paste.

Question 44Food Raw Materials: Cereals, Pulses, Fruits and Vegetables

Which of the following correctly matches a cereal with its typical processed product?

  1. Maize to dal
  2. Barley to besan
  3. Paddy rice to maida
  4. Wheat to semolina Correct answer.

Explanation

Wheat milling yields semolina as a coarse granular product along with flour, while rice gives polished rice and wheat gives maida. Dal and besan are pulse products, not cereal products.

Question 45Food Preservation Principles and Methods (thermal, drying, refrigeration, chemical)

In food preservation, the term 'sterilisation' of a canned product means that the process has been designed to destroy which of the following?

  1. All viable micro-organisms including heat-resistant bacterial spores Correct answer.
  2. Only the vegetative cells of Salmonella species
  3. Only the surface moulds that grow after opening
  4. Only the spoilage yeasts present on the raw fruit

Explanation

Commercial sterilisation aims at a heat treatment sufficient to inactivate all vegetative cells and the heat-resistant spores of Clostridium botulinum, so that the sealed can remains stable at ambient temperature. Killing only yeasts, salmonellae or surface moulds would leave spore formers able to spoil the product or produce toxin. The word therefore refers to the target of the process, not to a sterile hospital condition.

Question 46Food Preservation Principles and Methods (thermal, drying, refrigeration, chemical)

Blanching of vegetables before freezing is carried out mainly to inactivate which group of enzymes and thereby prevent off-flavour development during frozen storage?

  1. Oxidative and hydrolytic enzymes such as peroxidase and catalase Correct answer.
  2. Pectin methylesterase only
  3. Amylases that break down starch to sugar
  4. Lipases that hydrolyse neutral fats

Explanation

Blanching is a short hot-water or steam treatment that denatures the enzymes responsible for oxidative browning, off-flavour and vitamin loss during frozen storage; peroxidase and catalase are commonly used as indicator enzymes to check blanching adequacy. Lipases, pectin methylesterase and amylases exist in vegetables, but they are not the group that blanching is designed to control for frozen quality.

Question 47Food Preservation Principles and Methods (thermal, drying, refrigeration, chemical)

Which statement correctly describes the principle of freeze drying (lyophilisation) as used for instant coffee and dried fruit?

  1. Water is squeezed out mechanically from the frozen mass by pressing
  2. Water is removed as vapour from a frozen product by sublimation under reduced pressure Correct answer.
  3. Water is removed by soaking the frozen product in concentrated sugar syrup
  4. Water is boiled off at atmospheric pressure while the product remains frozen

Explanation

In lyophilisation the product is frozen and water is removed as vapour directly from ice by sublimation under vacuum, below the triple point, so the product stays frozen throughout. This preserves structure, aroma and rehydration quality. Mechanical pressing, boiling at atmospheric pressure, and osmotic soaking are different operations and do not describe sublimation drying.

Question 48Food Preservation Principles and Methods (thermal, drying, refrigeration, chemical)

Refrigeration at 0 to 5 degrees Celsius slows food spoilage mainly because at these temperatures microbial growth and enzyme activity are:

  1. Unaffected, since temperature does not influence spoilage
  2. Completely stopped for all micro-organisms
  3. Increased because cold activates enzymes
  4. Reduced in rate but not stopped Correct answer.

Explanation

Chilling reduces the metabolic rate of micro-organisms and the velocity of enzymatic reactions, so spoilage is delayed but continues. Psychrotrophic organisms such as Listeria and some Pseudomonas can still grow, and enzymes remain partly active. Refrigeration is therefore a preservative that extends shelf life rather than a treatment that stops deterioration completely.

Question 49Food Preservation Principles and Methods (thermal, drying, refrigeration, chemical)

Sodium chloride preserves foods such as pickles and salted fish chiefly by which mechanism?

  1. Acting as a strong oxidising agent on microbial cells
  2. Lowering water activity so that available moisture for micro-organisms is reduced Correct answer.
  3. Raising the pH of the food above 9
  4. Supplying nutrients that favour useful bacteria

Explanation

Salt dissolves in the food water and binds it, lowering water activity, which restricts the water available for microbial metabolism and causes plasmolysis of cells. The effect depends on concentration; a strong brine can inhibit most spoilage organisms. Salt does not raise pH, feed spoilage bacteria, or act as an oxidiser.

Question 50Food Preservation Principles and Methods (thermal, drying, refrigeration, chemical)

Which of the following is the correct description of the temperature range of the 'danger zone' that should be avoided during holding of cooked foods?

  1. Below freezing, that is, below 0 degrees Celsius
  2. Between about 5 and 60 degrees Celsius Correct answer.
  3. Above 100 degrees Celsius only
  4. Between 60 and 100 degrees Celsius

Explanation

Bacterial multiplication is fastest in the warm range roughly between 5 and 60 degrees Celsius, so cooked foods should be held either below about 5 degrees or above 60 degrees. Freezing stops growth, while temperatures above 60 degrees inhibit most vegetative cells. Holding food in the middle range for long periods allows rapid population increase.