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Punjab PSEB Senior Secondary NSQF Food Processing study materials
Punjab PSEB Senior Secondary NSQF Food Processing study resources

Punjab PSEB Senior Secondary NSQF Food Processing practice questions

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Question 1Introduction to Food Processing and Indian Food Industry

In the Indian food processing sector, which term describes the conversion of raw agricultural produce into shelf-stable products such as flour, oil, or canned goods through industrial methods?

  1. Food fortification
  2. Food processing Correct answer.
  3. Food hoarding
  4. Food adulteration

Explanation

Food processing refers to the set of industrial operations that transform raw agricultural commodities into stable, marketable products. Adulteration and hoarding are illegal practices, while fortification is only one specific processing intervention.

Question 2Introduction to Food Processing and Indian Food Industry

Which of the following is classified as a primary processed product rather than a secondary or tertiary one?

  1. Cleaned and graded wheat grain Correct answer.
  2. Packaged biscuits with cream filling
  3. Bread baked from wheat flour
  4. Ready-to-eat wheat porridge sachet

Explanation

Primary processing involves basic cleaning, grading, sorting, and simple preservation of the raw commodity with minimal change to its form. Bread, biscuits, and ready-to-eat porridge involve substantial transformation and are secondary or tertiary products.

Question 3Introduction to Food Processing and Indian Food Industry

Which Indian institution is the apex body responsible for standards and certification of processed foods sold in the domestic market?

  1. Agricultural and Processed Food Products Export Development Authority (APEDA)
  2. Indian Council of Agricultural Research (ICAR)
  3. Food Safety and Standards Authority of India (FSSAI) Correct answer.
  4. National Dairy Development Board (NDDB)

Explanation

FSSAI is the statutory authority under the Food Safety and Standards Act, 2006, that sets standards and regulates food businesses in India. ICAR handles agricultural research, NDDB supports dairy development, and APEDA promotes exports, so none of them set domestic food standards.

Question 4Introduction to Food Processing and Indian Food Industry

A Punjab food entrepreneur wants to sell packaged mango pickle in other states. Which legislation primarily governs the safety and labelling requirements of this product?

  1. Food Safety and Standards Act, 2006 Correct answer.
  2. Consumer Protection Act, 2019
  3. Essential Commodities Act, 1955
  4. Prevention of Food Adulteration Act, 1954

Explanation

The Food Safety and Standards Act, 2006 consolidated earlier food laws and now governs safety, standards, and labelling of all food products in India. The Prevention of Food Adulteration Act was repealed when FSSAI came into force.

Question 5Introduction to Food Processing and Indian Food Industry

Which of the following best describes the role of APEDA in the Indian food processing industry?

  1. Promoting exports of scheduled agricultural and processed food products Correct answer.
  2. Conducting food safety inspections of restaurants
  3. Setting maximum retail prices for packaged foods
  4. Regulating the import of agricultural machinery

Explanation

APEDA is a statutory export promotion body that facilitates and develops the export of scheduled agricultural and processed food products. It does not set retail prices, inspect restaurants, or regulate machinery imports.

Question 6Introduction to Food Processing and Indian Food Industry

Fruit and vegetable processing in Punjab is significant mainly because the state produces large surpluses that face which common problem in the fresh market?

  1. Complete absence of cold storage technology
  2. High perishability leading to post-harvest losses Correct answer.
  3. Lack of any irrigation facilities
  4. Legal ban on the sale of fresh produce

Explanation

Fresh fruits and vegetables are highly perishable, so surplus production often leads to spoilage and price crashes unless processed or stored. Processing converts such surplus into stable products with longer shelf life.

Question 7Introduction to Food Processing and Indian Food Industry

Which of the following is an example of a tertiary-level food processing activity?

  1. Milling paddy into rice
  2. Cleaning and bagging raw paddy
  3. Preparing and packaging a ready-to-eat meal for retail sale Correct answer.
  4. Drying freshly harvested maize

Explanation

Tertiary processing involves preparing ready-to-eat or ready-to-serve convenience foods, often combining several ingredients and packaging them for consumers. Cleaning, milling, and drying are primary operations.

Question 8Introduction to Food Processing and Indian Food Industry

Which of the following is a major reason for the growth of the packaged food industry in India?

  1. Complete self-sufficiency of every household in food production
  2. Prohibition of all food retail outlets
  3. Decline in the total population
  4. Rising urbanisation and demand for convenience foods Correct answer.

Explanation

Urbanisation, working couples, and changing lifestyles have increased demand for convenient, packaged, and ready-to-eat foods, driving industry growth. Population decline and household self-sufficiency would reduce rather than expand the market.

Question 9Introduction to Food Processing and Indian Food Industry

A cooperative in Punjab wants to set up a small unit to extract oil from mustard seed. This activity is best classified as which type of processing?

  1. Secondary processing of a dairy product
  2. Tertiary processing of a ready meal
  3. Primary processing of an oilseed Correct answer.
  4. Fortification of a cereal

Explanation

Oil extraction from an oilseed is a primary processing operation that separates oil from the raw seed with minimal ingredient addition. It is not ready-meal preparation, dairy processing, or cereal fortification.

Question 10Introduction to Food Processing and Indian Food Industry

Which of the following is a value-added product derived from milk?

  1. Paneer Correct answer.
  2. Wheat flour
  3. Mustard oil
  4. Rice bran

Explanation

Paneer is obtained by coagulating milk and is a classic value-added dairy product. Wheat flour, mustard oil, and rice bran are derived from cereals and oilseeds, not milk.

Question 11Introduction to Food Processing and Indian Food Industry

Which term refers to the loss of food quantity and quality between harvest and final consumption?

  1. Post-harvest loss Correct answer.
  2. Food fortification
  3. Food adulteration
  4. Food grading

Explanation

Post-harvest loss covers the reduction in quantity and quality of food from harvesting through storage, transport, and marketing until consumption. Fortification and grading are deliberate quality operations, while adulteration is intentional contamination.

Question 12Introduction to Food Processing and Indian Food Industry

A food processing unit in Ludhiana wants to label its product as 'organic'. Which certification route is relevant in India?

  1. Certification under the National Programme for Organic Production Correct answer.
  2. Licensing under the Essential Commodities Act
  3. Certification under the Bureau of Indian Standards hallmark scheme
  4. Registration under the Companies Act

Explanation

Organic food claims in India are regulated through the National Programme for Organic Production, which accredits certification bodies. BIS hallmarking applies to products such as gold jewellery, and the other laws do not certify organic status.

Question 13Introduction to Food Processing and Indian Food Industry

Which of the following best explains why processing reduces seasonal price fluctuations for farmers?

  1. It guarantees a fixed price by law for all crops
  2. It eliminates the need for any storage infrastructure
  3. It increases the water content of the produce
  4. It allows surplus produce to be stored and sold beyond the harvest season Correct answer.

Explanation

Processing converts perishable surpluses into stable products that can be stored and marketed later, smoothing supply across seasons and reducing price crashes at harvest. It does not add water, remove the need for storage, or legally fix prices.

Question 14Introduction to Food Processing and Indian Food Industry

Which of these is a secondary processed product of the cereal sector?

  1. Cleaned maize grain
  2. Paddy husk
  3. Freshly harvested wheat
  4. Breakfast cereal flakes Correct answer.

Explanation

Breakfast cereal flakes are produced by cooking, flaking, and toasting grain, which is a secondary transformation. Paddy husk is a by-product, while fresh wheat and cleaned maize are primary or raw commodities.

Question 15Introduction to Food Processing and Indian Food Industry

Which body is responsible for the development and regulation of the dairy industry in India at the national level?

  1. Spices Board
  2. Food Corporation of India
  3. National Dairy Development Board Correct answer.
  4. Marine Products Export Development Authority

Explanation

The National Dairy Development Board was set up to promote, plan, and organise dairy development programmes such as Operation Flood. The Food Corporation of India handles grain procurement and distribution, while the other boards cover spices and marine products.

Question 16Introduction to Food Processing and Indian Food Industry

A small unit wants to reduce spoilage of fresh peas without using chemical preservatives. Which traditional processing method is most suitable?

  1. Adding artificial colour
  2. Blanching and freezing Correct answer.
  3. Coating with non-food wax
  4. Storing in open sunlight for a week

Explanation

Blanching inactivates spoilage enzymes, and freezing then preserves peas for long periods without chemical preservatives. Adding colour or non-food wax does not preserve the product and may be unsafe, while open sunlight accelerates deterioration.

Question 17Introduction to Food Processing and Indian Food Industry

Which statement correctly distinguishes food processing from food manufacturing?

  1. Processing only involves cooking, while manufacturing only involves packaging
  2. Processing is illegal for small units, while manufacturing is legal
  3. Processing applies only to milk, while manufacturing applies only to cereals
  4. Processing applies preservation and conversion steps, while manufacturing typically combines ingredients into formulated consumer products Correct answer.

Explanation

Processing broadly refers to the steps that preserve and convert raw materials, whereas manufacturing generally denotes combining ingredients into formulated, branded consumer products. The other statements invent restrictions or narrow the terms incorrectly.

Question 18Introduction to Food Processing and Indian Food Industry

Which of the following is a key objective of food processing in the context of national food security?

  1. Removing all nutrients to make food lighter
  2. Extending shelf life to reduce wastage of surplus production Correct answer.
  3. Increasing the moisture content of grains for storage
  4. Eliminating the need for agriculture

Explanation

Processing extends shelf life, allowing surplus food to be stored and distributed, which reduces wastage and supports food security. Increasing moisture promotes spoilage, nutrient removal reduces quality, and agriculture remains essential.

Question 19Introduction to Food Processing and Indian Food Industry

Which of the following products is obtained by primary processing of sugarcane?

  1. Biscuit
  2. Chocolate bar
  3. Raw sugar after crushing and clarification Correct answer.
  4. Instant coffee

Explanation

Crushing sugarcane and clarifying the juice to obtain raw sugar is a primary processing operation. Chocolate, biscuits, and instant coffee involve different raw materials and more complex secondary processing.

Question 20Introduction to Food Processing and Indian Food Industry

A Punjab firm wants to export processed mango pulp to Europe. Which combination of requirements is most directly relevant?

  1. FSSAI licence for domestic compliance and APEDA registration with export quality standards Correct answer.
  2. Only a shop licence from the municipal committee
  3. Only a BIS hallmark on the packaging
  4. Only a company registration certificate

Explanation

Exporting processed food requires domestic food safety compliance through FSSAI and export facilitation through APEDA, along with meeting the destination market's quality standards. A shop licence, company registration, or BIS hallmark alone is insufficient.

Question 21Food Chemistry and Nutrition Basics

Which macronutrient is the body's most concentrated source of energy, supplying about 9 kcal per gram?

  1. Fat Correct answer.
  2. Protein
  3. Dietary fibre
  4. Carbohydrate

Explanation

Fat yields roughly 9 kcal per gram, whereas carbohydrate and protein each supply about 4 kcal per gram. Because fat is energy-dense, small amounts contribute substantially to total energy intake, which matters when formulating processed foods.

Question 22Food Chemistry and Nutrition Basics

A cereal product is analysed and found to contain 10 g protein, 60 g carbohydrate, 10 g fat and 5 g ash per 100 g. Approximately how many kilocalories does 100 g supply?

  1. 520 kcal
  2. 290 kcal
  3. 450 kcal
  4. 370 kcal Correct answer.

Explanation

Using Atwater factors, protein and carbohydrate give 4 kcal/g and fat gives 9 kcal/g: (10×4) + (60×4) + (10×9) = 40 + 240 + 90 = 370 kcal. Ash and moisture carry no energy and are excluded from the calculation.

Question 23Food Chemistry and Nutrition Basics

Which statement correctly describes an essential amino acid in human nutrition?

  1. It is only found in plant proteins and never in animal proteins.
  2. It is a fatty acid required for absorbing fat-soluble vitamins.
  3. It must be supplied through the diet because the body cannot make it in sufficient quantity. Correct answer.
  4. It can be synthesised in the body in adequate amounts.

Explanation

Essential amino acids cannot be synthesised by the human body at rates that meet requirements, so they must come from food. Animal and plant proteins both contain them, differing mainly in overall pattern and digestibility.

Question 24Food Chemistry and Nutrition Basics

Rice protein is low in lysine while pulse protein is low in methionine. What is the nutritional significance of eating rice and pulses together in one meal?

  1. The two proteins compete and reduce overall digestibility.
  2. Mixing them destroys the limiting amino acids present in each food.
  3. The combination converts plant protein into an essential fatty acid.
  4. Complementary amino acid patterns improve the overall protein quality. Correct answer.

Explanation

Cereals and pulses have complementary limiting amino acids, so combining them supplies a fuller essential amino acid pattern. This mutual supplementation raises the usable protein quality of the meal compared with either food eaten alone.

Question 25Food Chemistry and Nutrition Basics

Which lipid fraction is most strongly associated with raising LDL cholesterol when consumed in excess?

  1. Polyunsaturated fatty acids
  2. Saturated fatty acids Correct answer.
  3. Dietary fibre
  4. Monounsaturated fatty acids

Explanation

High intakes of saturated fatty acids are consistently linked with raised LDL cholesterol. Replacing part of the saturated fat with mono- or polyunsaturated fat lowers LDL, which is why fat quality matters in processed food formulation.

Question 26Food Chemistry and Nutrition Basics

During deep frying, oil is repeatedly heated to high temperature. Which change is a characteristic result of this thermal abuse?

  1. Reduction of free fatty acids to zero
  2. Formation of polar compounds and off-flavours from oxidation and hydrolysis Correct answer.
  3. Increase in the oil's vitamin E content
  4. Complete conversion of triglycerides into protein

Explanation

Repeated heating drives oxidation, hydrolysis and polymerisation, producing polar compounds, free fatty acids and off-flavours. These changes reduce frying quality and are monitored as an indicator of oil degradation.

Question 27Food Chemistry and Nutrition Basics

Which enzyme breaks down starch into smaller dextrins and sugars during food processing and digestion?

  1. Protease
  2. Amylase Correct answer.
  3. Lipase
  4. Pectinase

Explanation

Amylase hydrolyses glycosidic bonds in starch, yielding dextrins, maltose and glucose. Its action explains sweetness development in products such as mashing grains or dough fermentation.

Question 28Food Chemistry and Nutrition Basics

Which property of gelatinisation explains why a starch-thickened sauce becomes firm on cooling?

  1. Starch chains are broken into fatty acids by heat.
  2. Starch granules dissolve completely into simple sugars when heated.
  3. Starch repels water and separates as a dry powder.
  4. Starch granules absorb water and swell irreversibly when heated, then form a gel network on cooling. Correct answer.

Explanation

On heating in water, starch granules absorb water, swell and lose their crystalline order, releasing amylose that forms a network. On cooling this network sets into a gel, giving thickness and body to the sauce.

Question 29Food Chemistry and Nutrition Basics

Which vitamin is water-soluble and therefore most vulnerable to leaching into cooking water and destruction by prolonged boiling?

  1. Vitamin A
  2. Vitamin E
  3. Vitamin D
  4. Vitamin C Correct answer.

Explanation

Vitamin C is water-soluble and heat-labile, so it leaches into cooking water and is readily lost during prolonged boiling. The fat-soluble vitamins A, D and E are less affected by leaching into water.

Question 30Food Chemistry and Nutrition Basics

A food processor wants to reduce vitamin C loss in a vegetable product. Which processing choice best supports this aim?

  1. Adding an oxidising agent before heating
  2. Blanching briefly and minimising exposure to heat, light and oxygen Correct answer.
  3. Storing the product warm in an open vessel for several hours
  4. Prolonged boiling in a large volume of water

Explanation

Vitamin C is destroyed by heat, light, oxygen and leaching, so short blanching with limited water and controlled exposure preserves it best. Rapid cooling and exclusion of air further reduce oxidative loss.

Question 31Food Chemistry and Nutrition Basics

Which mineral is a key component of the haemoglobin molecule and is best absorbed from animal sources?

  1. Iron Correct answer.
  2. Calcium
  3. Iodine
  4. Potassium

Explanation

Iron is central to haemoglobin, where it binds oxygen for transport in blood. Haem iron from animal foods is absorbed more efficiently than non-haem iron from plant foods, which is influenced by enhancers and inhibitors in the meal.

Question 32Food Chemistry and Nutrition Basics

A person eats a meal rich in vitamin C together with a plant food containing non-haem iron. What is the likely effect on iron absorption?

  1. Absorption is unaffected because only haem iron can be absorbed.
  2. Absorption is enhanced because vitamin C helps keep iron in the more absorbable ferrous form. Correct answer.
  3. Absorption stops completely because the two nutrients compete.
  4. Absorption is reduced because vitamin C binds iron tightly.

Explanation

Ascorbic acid reduces ferric iron to the more absorbable ferrous form and forms a soluble complex, enhancing non-haem iron uptake. This is why pairing vitamin C-rich foods with plant iron sources improves iron nutrition.

Question 33Food Chemistry and Nutrition Basics

Which statement best describes the role of dietary fibre in digestion?

  1. It is absorbed directly into the bloodstream without change.
  2. It is fully digested and absorbed in the small intestine as glucose.
  3. It resists digestion in the small intestine and supports bowel function and regularity. Correct answer.
  4. It provides 9 kcal per gram, like fat.

Explanation

Dietary fibre passes largely undigested through the small intestine and is fermented in the colon or adds bulk, supporting regularity and bowel health. Its energy contribution is small compared with fat.

Question 34Food Chemistry and Nutrition Basics

A bakery replaces part of its white flour with whole-grain flour. Which nutritional change is most directly expected?

  1. Higher content of dietary fibre and micronutrients from the bran and germ Correct answer.
  2. Complete removal of all starch from the product
  3. Loss of all B vitamins because of the germ
  4. Higher saturated fat content from the bran layer

Explanation

Whole-grain flour retains bran and germ, which carry fibre, B vitamins, minerals and phytochemicals that refining largely removes. The starch content remains substantial rather than disappearing.

Question 35Food Chemistry and Nutrition Basics

Which process is chiefly responsible for the browning of bread crust during baking?

  1. Hydrolysis of starch into fatty acids
  2. Simple evaporation of water from the surface
  3. Fermentation of lactose by yeast
  4. Maillard reaction between reducing sugars and amino groups Correct answer.

Explanation

During baking, reducing sugars react with amino groups of proteins in the Maillard reaction, producing brown pigments and characteristic aroma compounds. This non-enzymatic browning is distinct from caramelisation of sugars alone.

Question 36Food Chemistry and Nutrition Basics

Which change in a food system is an example of enzymatic browning?

  1. Darkening of cut apple surfaces caused by polyphenol oxidase Correct answer.
  2. Browning of sugar heated alone to form caramel
  3. Yellowing of fat caused by oxidation
  4. Browning of bread crust during baking

Explanation

Cutting fruit exposes polyphenols to polyphenol oxidase and oxygen, producing brown melanins; this is enzymatic browning. It can be limited by blanching to inactivate the enzyme or by excluding oxygen.

Question 37Food Chemistry and Nutrition Basics

A sample of milk is tested and found to have a pH of about 6.6. Which description of milk is consistent with this value?

  1. Exactly neutral at pH 7.0
  2. Strongly acidic, similar to lemon juice
  3. Slightly acidic, close to neutral Correct answer.
  4. Strongly alkaline, similar to soap

Explanation

A pH of about 6.6 is just below neutral 7.0, so milk is very slightly acidic. This value is important because acid development by bacteria lowers pH further and causes casein to coagulate.

Question 38Food Chemistry and Nutrition Basics

Which statement correctly explains why water activity is used alongside moisture content to predict food spoilage?

  1. Water activity measures the pH of the food.
  2. Water activity measures the total weight of water in the food.
  3. Water activity measures the water available for microbial growth rather than total water present. Correct answer.
  4. Water activity equals the fat content of the food.

Explanation

Water activity reflects the fraction of water that is unbound and available to microorganisms and chemical reactions. Two foods with the same moisture content can differ in stability because their water is bound to different degrees.

Question 39Food Chemistry and Nutrition Basics

A food technologist wants to slow lipid oxidation in a snack containing polyunsaturated oil. Which approach is most directly effective?

  1. Raising the storage temperature to speed equilibration
  2. Increasing the level of polyunsaturated oil in the recipe
  3. Storing the product in clear packaging under bright light
  4. Adding a chelating agent and an antioxidant while excluding oxygen and light Correct answer.

Explanation

Lipid oxidation is promoted by oxygen, light, heat and trace metals, so antioxidants, chelators and protective packaging slow the reaction. Removing these promoters extends shelf life more reliably than changing the oil level.

Question 40Food Chemistry and Nutrition Basics

Which combination of findings best indicates that a cereal-based food is a good source of quality protein for a vegetarian diet?

  1. High fat content with low protein content
  2. Very low protein digestibility with high fibre content
  3. Adequate protein quantity together with a pattern supplying the limiting essential amino acids Correct answer.
  4. High total protein content alone, regardless of amino acid pattern

Explanation

Protein quality depends on both the amount and the essential amino acid pattern, together with digestibility. A food that supplies adequate quantity and covers limiting amino acids supports protein needs better than one judged on quantity alone.

Question 41Food Microbiology and Spoilage

In food processing, which group of microorganisms is most commonly responsible for spoilage of refrigerated, vacuum-packed foods because it can grow without oxygen and at low temperature?

  1. Lactic acid bacteria such as Lactobacillus Correct answer.
  2. Thermophilic spore formers such as Geobacillus
  3. Photosynthetic algae
  4. Obligate aerobic moulds such as Aspergillus

Explanation

Lactic acid bacteria are facultative anaerobes that tolerate refrigeration and grow in vacuum packs, producing souring, gas and slime. Aerobic moulds need oxygen, algae need light, and thermophiles need high temperatures, so none fit cold anaerobic storage.

Question 42Food Microbiology and Spoilage

A batch of canned peas shows swollen, bulging ends after storage. Which organism is most likely responsible for this type of spoilage?

  1. Lactobacillus plantarum causing flat sour
  2. Clostridium botulinum producing gas and toxin Correct answer.
  3. Saccharomyces cerevisiae causing surface film
  4. Rhizopus stolonifer causing black mould

Explanation

Swollen cans with gas production point to anaerobic spore formers such as Clostridium botulinum or other Clostridium species that ferment sugars and release gas. Flat-sour organisms produce acid without gas, yeasts need oxygen, and Rhizopus is an aerobic mould.

Question 43Food Microbiology and Spoilage

Which intrinsic factor of a food most directly determines whether bacteria or moulds will dominate its spoilage flora?

  1. Shape of the container
  2. Water activity of the food Correct answer.
  3. Colour of the packaging
  4. Ambient humidity of the storeroom

Explanation

Water activity is an intrinsic property of the food itself and sets which microorganisms can multiply; bacteria generally need higher aw than xerophilic moulds. Humidity, packaging colour and container shape are extrinsic or irrelevant factors.

Question 44Food Microbiology and Spoilage

A food technologist wants to preserve fruit juice by lowering pH. Which pH range will most effectively inhibit the growth of most spoilage bacteria?

  1. Between pH 6.0 and 6.5
  2. Around pH 8.0
  3. Between pH 7.0 and 7.5
  4. Below pH 4.6 Correct answer.

Explanation

Most spoilage bacteria, including pathogens such as Clostridium botulinum, are inhibited below pH 4.6, which is why this value is used to define acidified foods. Neutral and alkaline ranges favour bacterial growth.

Question 45Food Microbiology and Spoilage

During preparation of a fermented pickle, salt is added to the brine. What is the main microbiological purpose of this salt?

  1. To increase the water activity of the product
  2. To raise the pH and encourage mould growth
  3. To reduce water activity and select for salt-tolerant lactic acid bacteria Correct answer.
  4. To supply nitrogen for bacterial protein synthesis

Explanation

Salt lowers water activity, suppressing many spoilage organisms while allowing halotolerant lactic acid bacteria to ferment sugars into acid. It does not raise pH, provide nitrogen, or increase water activity.

Question 46Food Microbiology and Spoilage

Which of the following is a classic sign of proteolytic spoilage in a protein-rich food such as fish?

  1. Development of a sweet fruity aroma
  2. Production of ammonia and putrid odours Correct answer.
  3. Increase in vitamin C content
  4. Formation of a hard dry crust

Explanation

Proteolytic bacteria break down proteins into amines and ammonia, producing the putrid odours typical of spoiled fish. Sweet aromas, dry crusts and rising vitamin C are not associated with protein breakdown.

Question 47Food Microbiology and Spoilage

A dairy plant finds that pasteurised milk spoils rapidly even when kept at 4 degrees Celsius. Which group of psychrotrophic organisms is the most likely cause?

  1. Pseudomonas species Correct answer.
  2. Halophilic Vibrio species
  3. Thermophilic Bacillus species
  4. Obligate anaerobic Clostridium species

Explanation

Pseudomonas species are psychrotrophic Gram-negative rods that grow at refrigeration temperature and cause off-flavours and proteolysis in cold-stored milk. Thermophiles need heat, clostridia are anaerobic, and Vibrio is halophilic and not typical of milk.

Question 48Food Microbiology and Spoilage

Which method directly measures viable microbial numbers in a food sample by counting colonies that develop on a nutrient agar plate?

  1. Standard plate count Correct answer.
  2. Water activity determination
  3. pH measurement
  4. Titratable acidity test

Explanation

The standard plate count enumerates viable cells as colony-forming units after incubation on agar. pH, water activity and titratable acidity are chemical or physical indicators and do not count living cells.

Question 49Food Microbiology and Spoilage

A laboratory wants to detect coliform contamination in a water sample used for food processing. Which test is most appropriate as a presumptive indicator?

  1. Measurement of refractive index
  2. MacConkey broth fermentation with gas production Correct answer.
  3. Estimation of crude fibre
  4. Gram staining of a pure culture

Explanation

Coliforms ferment lactose with gas production in MacConkey broth, which serves as a presumptive indicator of faecal contamination. Gram staining alone is not a presumptive test, and refractive index and crude fibre are unrelated to microbial contamination.

Question 50Food Microbiology and Spoilage

Which of the following best describes the role of an indicator organism such as Escherichia coli in food safety testing?

  1. It acts as a natural preservative in canned goods
  2. Its presence suggests possible faecal contamination and enteric pathogens Correct answer.
  3. It directly causes all food poisoning outbreaks
  4. It improves the flavour of fermented foods

Explanation

E. coli is a faecal indicator whose presence signals possible contamination with enteric pathogens, even when the pathogens themselves are not detected. It is not the cause of all outbreaks, nor a flavouring or preservative agent.