Table of Contents
Q.1. List and discuss the various factors responsible for growth of bacteria. Also explain growth curve of bacteria.
FACTORS AFFECTING GROWTH OF MICROORGANISMS
1. TEMPERATURE
Microorganisms have optimum growth temperature .They do not grow above or below a specific range of temperature. Bacteria can grow and survive under more extreme conditions than those tolerated by any of the molds or yeasts. Bacteria’s are classified as:-
Psychrophiles – 68 °-77 °F (45 °F) (0-20 °C)
Mesophiles – 98 °F (20 °-45 °C)
Thermophiles – 110 °F (45 °-60 °C)
Moulds can grow and can survive under more extreme conditions than can the yeasts.
2. WATER
Microorganisms grow in aqueous solutions. A term, “water activity (aw)” express the degree of availability of water in foods. Foods with high water content deteriorate fast. Leafy vegetables, fruits, meat, milk deteriorate rapidly. Fruits & vegetables can give of moisture from respiration & transpiration even when packed in a moisture free package. This moisture is enough for microorganisms to grow.
3. pH (hydrogen ion concentration)
Moulds, yeast grow best at PH on the acidic side of neutrality as do some bacteria. Many species of bacteria grow at PH which are at neutrality or slightly on alkaline side. Extreme PH for bacteria (PH 4 – PH 11)
4. NUTRITIONAL REQUIREMENTS OF MICROBES
Microorganisms especially bacteria vary greatly from species to species. In the presence of some inorganic salts some bacteria can utilize the nitrogen in air to form proteins and carbon dioxide in air to obtain energy they also use lactates as source of energy. Moulds and yeast like bacteria require basic elements – carbon, hydrogen, nitrogen, phosphorus, sodium, sulphur etc. as well as vitamins & other organic compounds.
5. OXYGEN REQUIREMENT
Some bacteria are aerobic that is they require oxygen for growth. Some both presence and absence (facultative aerobes/anaerobes) bacteria that do not require oxygen – anaerobes. Moulds & yeast require.
The curve is divided into phase as indicated in the fig:
(1) The initial lag phase (A to B), during which there is no growth or even a decline in numbers.
(2)The phase of positive acceleration the rate of growth is continuously increasing. (3)The log or exponential phase of growth (C to D), during which the rate of multiplication is most rapid and is constant.
(4)The phase of negative acceleration (D to E), during which the rate of multiplication is decreasing.
(5)The maximal stationary phase (E to F), where numbers remain constant.
(6)The accelerated death phase (F to G).
(7)The death phase or phase of decline (G to H), during which numbers decrease at a faster rates then new cells are formed and
(8)The survival phase (H to I) during which no cell division occur but remaining cells survive on endogenous nutrients.
Q.2. Define Food Additive. Classify and explain various food additives being used in hotel kitchen.
Food additives can be defined as a substance or a mixture of substances other than the basic food stuff which is present in food as a result of any aspect of production, processing, storage or packaging. Food additives are used intentionally and are expected to become a component of the food to which they are added. They prevent deterioration and thereby prolong shelf life. They enhance sensory qualities and make the food attractive and appetizing for the consumer. They also provide and improve the functional property of the food and improve or maintain the nutritional value. They also facilitate processing, packaging, transport or storage of food.
1.Sweetners
-Add sweetness with or without extra calories
-Used in beverages, sweets, confectionary, processed foods
-Eg: Sucrose, glucose, aspartame, sorbitol, corn syrup, aspartame, sucralose
2.Antioxidants
-Delay rancidity and prevent changes in colour, flavor or texture -Used in oils and margarine, cereals, dressings, baked goods
-Eg: Butylated hydrocyanisole, butylated hydroxytoluene, tocopherols
3.Preservatives
-Prevent food from microorganisms
-Used in fruit beverages, baked goods, cured meats etc
-Eg: Sodium benzoate, calcium propionate, citric acid, sodium nitrate, calcium sorbate
4.Colours
-Correct natural variations in colour and enhance colours that occur naturally -Used in Sweetmeats, candies, cheese, jams, soft beverages, pie fillings etc -Eg: Sunset yellow Indigo carmine, fast green, annatto extract, caramel, saffron
5. Flavours
-Enhance flavor already present In food -Used in processed foods
-Eg: MSG, hydrolyzed soy protein
6.Emulsifiers
-Prevent separation and keeps emulsified product stable -Used in salad dressing, mayo, frozen desserts, chocolate etc -Eg: Soy lecithin,egg yolks, sorbitan monostearate
7. Stabalizers and thickeners
-Produce uniform texture and improves mouth feel
-Used in frozen desserts, dairy products, cakes, soup powders, dressings, sauces -Eg: Gelatin, chitin, guar gum, agar agar,Xanthan gum, whey
8. Leavening Agents
-Promote rising of baked goods
-Used in cakes, biscuits, breads etc
-Eg: Baking powder, Baking soda, calcium carbonate
9. Dough conditioners
-Produce more stable dough
-Used in baked goods
-Eg: Ammonium chloride, potassium bromated
10. Fat replacers
-Provide expected texture and a creamy mouthfeel in reduced fat foods
-Used in baked goods, dressings, frozen desserts, cakes, dairy products
-Eg: cellulose gel, olestra, carrageenan, modified food starch, guar hum, whey protein concentrate
OR Discuss in detail the various methods of food preservation.
Food preservation is the process of treating and handling food to stop or slow down food spoilage, loss of quality, edibility, or nutritional value and thus allow for longer food storage.
Various methods of food preservation are as follows:
Asepsis
The principle of asepsis works on preventing the entry of disease causing and spoilage organisms.
Aseptic packaging
Aseptic processing
Use of high temperature
Heating extends the shelf life of food by killing microorganisms through denaturation od proteins and inactivation of enzymes
Blanching– Pretreatment usually carried out in vegetables prior to dehydration, freezing or canning to inactivate the enzymes. The vegetables are dipped in boiling water for 1-5 minutes.
Pasteurization- It is a mild heat treatment which is carried out at a temperature below 100°c followed by immediate cooling to kill the undesirable microorganisms. Important for processing milk.
Sterlization- Severe heat treatment at a temperature of 121°c which results in complete destruction of microorganisms and also alters the organoleptic and nutritive quality of food adversely.
Use of low temperature
The underlying principle of low temperature preservation is that it decreases the rate of chemical and enzymatic reactions and controls the replication and propagation of microorganisms
Refrigeration- Doesn’t destroy microbes, but slows down their enzymatic activity and prevents their replication, thereby delaying spoilage
Freezing- preserves by converting water into ice and making it unavailable for microbial and enzymatic growth
Removal of moisture
Sun drying- Slow process limited to hot and dry climate and is suitable for a few fruits Dehydration- Complete removal of moisture from food under controlled conditions of temperature , humidity and air velocity in dehydrators. Drying preserves food, prolongs its shelf life, decreases itl bulk, and weight as well as the transportation and packaging costs.
Concentration- Employed for liquid foods. Concentration decreases the moisture content by 20%
Use of preservatives
They are food additives which are intentionally added to inhibit, retard or arrest the growth of microorganisms and thereby preventing fermentation, acidification or other decomposition of food.
Class I preservatives- Safe for human consumption and can be added to any amount to food. Eg: sugar, salt, spices, vinegar etc.
Class II preservatives- Chemicals used within prescribed limits. Eg: benzoic acid, sulphites, nitrates etc.
Modification of pH
Microbe growth is inhibited if pH is changed from its ideal level and increased or decreased.
Adding organic acids
Fermentation
Irradiation
Works on the principle that ionizing radiations interact with food material by transferring energy to the electrons and ionizing molecules by creating positive and negative charge. Different methods are Radurization Radicidation Radapperrtization.
Q.3. What do you mean by food adulteration? Enlist various food adulterants.
An adulterant is a pejorative term for a substance found within other substances such as food, fuels or chemicals even though it is not allowed for legal or other reasons.
It will not normally be present in any specification or declared contents of the substance, and may not be legally allowed. The addition of adulterants is called adulteration. The most common reason for adulteration is the use by manufacturers of undeclared materials that are cheaper than the correct and declared ones. The adulterants may be harmful, or reduce the potency of the product, or they may be harmless.
Various food adulterants added to food are:
Butter and Cream: Anatta is added to give a yellow tinge to butter. A byproduct of beef fat called oleomargarine is added in large quantities to butter. Cream is adulterated with gelatin and formaldehyde is added to increase the shelf life. Vanaspati is added to pure ghee and butter.
Ice Cream: Washing powder is regularly added to add volume to ice cream.
Milk, Paneer, Khoya: Urea, Starch and washing powder is added.
Tumeric, Coriander powder, Red Chilies: Tumeric is mixed with metanil yellow, colored chalk powder, aniline dyes; wood powder is added to both turmeric and coriander, while red chilies is mixed with Red color dye, Sudan Red III color and brick dust.
Mustard: Argemone seeds are regularly added.
Spice Powder: Barn is added along with synthetic colors.
Cinnamon Bark: Cassia bark is added.
Cumin seeds: Grass seeds colored with charcoal is mixed.
Pulses: Moong, Chana etc: Lead Chromate is added on a regular basis. Kesari dal is added to Besan and yellow dal.
Tea: Iron filings, colored tea leaves, used.
Coffee: Chicory is mixed with the powder.
Wheat Flour: Chalk powder, barn dust and sand is added.
Confectionary: Colours that have a harmful effect on the body are added to confectionary items that children consume on a regular basis and they include copper, Prussian blue, arsenic compounds, chrome yellow etc.
Vegetables: Copper salts are added to color the vegetables with green.
Vegetable Oils: Castor oil, Mineral oil, Argemone oil, Kranaja oil is added.
OR Discuss beneficial role of microorganisms in food industry.
Microorganisms play an important role in food industry, they are used in production of various food products. Beneficial microbes, if consumed within limit, have health benefite. They help in preventing the growth and multiplication of harmful organisms. They can also be useful in the preservation of food.
Fermentation and Role of Lactic Acid Bacteria
The conversion of carbohydrates to alcohols and crbon dioxide or organic acids by yeast, bacteria or a combination under anaerobic conditions. Based on the source of microorganisms, food can be fermented In three ways:
- Natural fermentation
- Back sloping
- Controlled fermentation
Some application in the food industry
1.Fermentation in dairy products– Cheese, yoghurt, buttermilk, sour cream, probiotic milk and curd
2.Fermented vegetables– Saurkraut, kimchi, vegetable pickles, pickled olives, cucmber, carrots, beans, peas and corn
3.Fermented cereal products– Breads, pizza, idli, dosa, jalebi, sour rice, angkhak
4.Fermented legume products– Soy sauce, tamari sauce, miso, tempeh, natto, Punjabi waries, tofu, papadam
5.Alcoholic beverages– Wine, beer, spirits
6.Fermented meat products– Salami, pepperoni, sausage, pickled meat, nahm, thuringer
7.Fermented fish products– Fish sauces, pickled fish, bagoong, tarma, paak, mamoni
8.Other fermented foods– Vinegar, red palm oil, organic acids, enzymes, flavours, amino acids, vitamins
Q.4. Write short notes on any two:
(a) Essential Commodities Act
The Essential Commodities Act is an act of Parliament of India which was established to ensure the delivery of certain commodities or products, the supply of which if obstructed owing to hoarding or black marketing would affect the normal life of the people. This includes foodstuff, drugs, fuel (petroleum products) etc.
The ECA was enacted way back in 1955. It has since been used by the Government to regulate the production, supply and distribution of a whole host of commodities it declares essential order to make them available to consumers at fair prices
(b) AGMARK
AGMARK is a certification mark employed on agricultural products in India, assuring that they conform to a set of standards approved by the Directorate of Marketing and Inspection, an agency of the Government of IndiaThe AGMARK is legally enforced in India by the Agricultural Produce (Grading and Marking) Act of 1937 (and amended in 1986).[1] The present AGMARK standards cover quality guidelines for 213 different commodities spanning a variety of pulses, cereals, essential oils, vegetable oils, fruits and vegetables and semi-processed products like vermicelli.
(c) FPO
The FPO mark is a certification mark mandatory on all processed fruit products sold in India such as packaged fruit beverages, fruit-jams, crushes and squashes, pickles, dehydrated fruit products, and fruit extracts, following the Food Safety and Standards Act of 2006. The FPO mark guarantees that the product was manufactured in a hygienic ‘food-safe’ environment, thus ensuring that the product is fit for consumption.
Q.5. Why personal hygiene is important in food sector?
Good personal hygiene can prevent food poisoning.
Bacteria that cause food poisoning can be on everyone – even healthy people. You can spread bacteria from yourself to the food if you touch your nose, mouth, hair or your clothes, and then food.
Good personal hygiene also makes good business sense. Customers like to see food- handling staff who take hygiene seriously and practise safe food handling.
Food handlers may contaminate food, so employers and employees must be careful to ensure that no illness is passed on by those working in the industry
To prevent food poisoning using good personal hygiene, a person in the food sector must try to follow these tips:
- wash and dry your hands thoroughly before handling food, and wash and dry them again frequently during workdry your hands with a clean towel, disposable paper towel or under an air dryer
- never smoke, chew gum, spit, change a baby’s nappy or eat in a food handling or food storage area
- never cough or sneeze over food, or where food is being prepared or stored
- wear clean protective clothing, such as an apron
- keep your spare clothes and other personal items (including mobile phones) away from where food is stored and prepared
- tie back or cover long hair
- keep fingernails short so they are easy to clean, and don’t wear nail polish because it can chip into the food
- avoid wearing jewellery, or only wear plain-banded rings and sleeper earrings
- completely cover all cuts and wounds with a wound strip or bandage (brightly coloured waterproof bandages are recommended)
- wear disposable gloves over the top of the wound strip if you have wounds on your hands, change disposable gloves regularly
advise your supervisor if you feel unwell, and don’t handle food.
Q.6. Discuss HACCP and its principles.
HACCP was developed with the objective of making space food microbiology safe during a space Food Project of NASA and the US Army in collaboration with the Pillsbury company. It is widely used as a system to prevent physical, biological, and chemical hazards, which can compromise the safety of food meant for human consumption. It is a system which identifies, evaluates and control hazards which are significant for food safety. It helps to enlist the potential risks associated with food production, identify causes and assesses their effects before deploying an effective control mechanism
The Seven HACCP Principles
Principle 1: Conduct hazard analysis.
Plants determine the food safety hazards identify the preventive measures the plant can apply to control these hazards.
Principle 2: Identify critical control points.
A critical control point (CCP) is a point, step, or procedure in a food process at which control can be applied and, as a result, a food safety hazard can be prevented, eliminated, or reduced to an acceptable level. A food safety hazard is any biological, chemical, or physical property that may cause a food to be unsafe for human consumption.
Principle 3: Establish critical limits for each critical control point.
A critical limit is the maximum or minimum value to which a physical, biological, or chemical hazard must be controlled at a critical control point to prevent, eliminate, or reduce to an acceptable level.
Principle 4: Develop critical control point monitoring procedure
Monitoring activities are necessary to ensure that the process is under control at each critical control point. FSIS is requiring that each monitoring procedure and its frequency be listed in the HACCP plan.
Principle 5: Create protocols for critical control point deviations
These are actions to be taken when monitoring indicates a deviation from an established critical limit. The final rule requires a plant’s HACCP plan to identify the corrective actions to be taken if a critical limit is not met. Corrective actions are intended to ensure that no product injurious to health or otherwise adulterated as a result of the deviation enters commerce.
Principle 6: Ensure correct record keeping and documentation
The HACCP regulation requires that all plants maintain certain documents, including its hazard analysis and written HACCP plan, and records documenting the monitoring of critical control points, critical limits, verification activities, and the handling of processing deviations.
Principle 7: Verify effectiveness of the HACCP system
- Validation ensures that the plans do what they were designed to do; that is, they are successful in ensuring the production of safe product. Plants will be required to validate their own HACCP plans. FSIS will not approve HACCP plans in advance, but will review them for conformance with the final rule.
- Verification ensures the HACCP plan is adequate, that is, working as intended. Verification procedures may include such activities as review of HACCP plans, CCP records, critical limits and microbial sampling and analysis. FSIS is requiring that the HACCP plan include verification tasks to be performed by plant personnel. Verification tasks would also be performed by FSIS inspectors. Both FSIS and industry will undertake microbial testing as one of several verification activities. the occurrence of the identified food safety hazard.
Q.7. What are various cleaning agents used in hotel industry?
Cleaning agents are the most critical aids of housekeeping department in their day to day operations to keep the room and public area neat and clean.
Cleaning agents such as detergents are generally mixed with other components such as water, surfactants in organic and inorganic acids and inorganic alkalis for improving their efficiency.
Cleaning procedures are an integral part of the sanitation plan in a food processing unit. Floors, walls, ceilings and drains are cleaned generally during shutdown period by either dry cleaning or wet cleaning. Dry cleaning comprises of mechanical removal of soil by sweeping, wiping, brushing and vacuum cleaning. Among these, vacuum cleaning is the most preferable option as it removes dust, without spreading.
Wet cleaning of equipment can be carried out in two ways:
1. Clean in place
2. Clean out of place
Common agents used:
-High temperature is a good sanitizer because it has high penetration, is non corrosive and leaves no residue.
– Chemical sanitizers are more suitable and cost effective for open surfaces such as conveyor belts.
– Commonly used sanitizers include chlorine releasing compounds, ammonium compounds, iodophors, force bromine compounds, acid sanitizers, ozone and peroxides.
Q.8. What is GMF and BSE?
According to the World Health Organization, “Genetically modified organisms (GMOs) can be defined as organisms (i.e. plants, animals or microorganisms) in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating and/or natural recombination. Genetically modified foods are foods in which the genetic material has been altered in a way that does not occur naturally. They provide improved yield and thereby increase the profit. The crop protection is also better due to increased resistance to plant diseases caused by insects or virus. For example, BT brinjal has been developed by introducing a gene from a different organism.
Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a transmissible spongiform encephalopathy and fatal neurodegenerative disease in cattle that causes a spongiform degeneration of the brain and spinal cord. BSE has a long incubation period, of 2.5 to 5 years, usually affecting adult cattle at a peak age onset of four to five years. The disease may be most frequently transmitted to humans by eating food contaminated with the brain, spinal cord, or digestive tract of infected carcasses. However, the infectious agent, although most highly concentrated in nervous tissue, can be found in virtually all tissues throughout the body, including blood. When it has been transmitted to humans, it is known as new variant
OR Discuss various food borne diseases.
Food borne diseases are illnesses that are either infectious or toxic in nature, caused by agents which enter the body through the ingestion of food.
Categories of food borne diseases:
1. Food infections
- Bacterial
- Viral
- Parasitic
2. Food intoxication
- Bacterial
- Fungal
- Chemical
Pathogens causing foodborne illnesses:
1. Pathogens causing most food borne illnesses
- – Norovirus
- – Salmonella
- – Clostridium perfringens
- – Campylobacter spp.
- – Staphylococcus aureus
2. Pathogens causing most food borne illnesses resulting in hospitalization
- – Salmonella
- – Norovirus
- – Camphylobacter spp
- – Toxoplasma gondii
- – E. coli
3. Pathogens causing most food borne illnesses resulting in death
- – Salmonella
- – Toxoplama gondii
- – Listeria monocytogenes
- – Norovirus
- – Campylobacter spp.
When disease causing microorganisms or parasites are present in the food at the time of consumption and grow in the body of the host to cause illness, the condition is known as food infection.
In case of food intoxication, the toxins are present in the food prior to its consumption.
Some food borne diseases:
- Salmonellosis, caused by Salmonella
- Clostridium perfringens illness, caused by Clostridium perfringens
- Scarlet fever, caused by Streptococcus pyogenes
- Cholera, caused by Vibrio cholera
- Gastroenteritis, caused by Norovirus
- Hepatitis A, caused by HAV
- Amoebic dysentery, caused by Entamoeba histolytica
- Ascariasis, caused by Ascaris lumbricoides
- Botulism, caused by Clostridium Botulinum
- Staphylococcus food intoxication, caused by Staphylococcus aureus