_food and-food contamination & spoilage-.pdf
- 5. • Dairy and dairy alternatives - good sources of proteins and vitamins. They also contain calcium which is essential for bone health. • Starch - required to fuel the body and is a good source of energy. -whole grain foods or carbohydrates contain essential fiber, calcium, iron and other vitamins. • Protein – is an important component of many meals, culture, lifestyle and a wide variety of foods are eaten from this food group. Pulses are foods such as beans and peas. They are a good source of fiber, vitamins and minerals and are low in fat. Vegetable-based sources of proteins include tofu and bean curd. They are full of proteins, low in fat and can be an alternative for meat in most recipes. Fish is rich in proteins, vitamins and minerals. Oil-rich fish such as salmon contain Vitamin A, Vitamin D and omega-3 fatty acids that benefit the heart, skin, nails, memory and digestion.
- 6. WHAT IS FOOD? • is any nutritious substance that people or animals eat or drink or that plants absorb to maintain life to provide energy and development to stimulate growth
- 7. WHAT IS THE DIFFERENCE?
- 8. WHAT IS SPOILAGE? • Spoilage is the process in which food deteriorates to the point in which it is not edible to humans or its quality of edibility becomes reduced OR • Any change which renders a product unacceptable for human consumption. • Complex event in which a combination of microbial and biochemical activities may interact. • One of the major reason that led to preservation.
- 9. FACTORS DETERMINING THE SPOILAGE • Microbial colonization depends on – characteristics of product – The way processed – The way stored • Factors are characterized into four: – Intrinsic parameters – Extrinsic parameters – Modes of preservation and processing – Implicit parameters
- 10. INTRINSIC PARAMETERS • Physical, chemical and structural properties. • Inherent in the food itself. • Important factors include water activity, acidity, redox potential, available nutrients and natural antimicrobial substances. EXTRINSIC PARAMETERS • Factors in the environment where food is stored • Temperature, humidity and atmosphere conditions.
- 11. MODES OF PRESERVATION AND PROCESSING • Physical or chemical treatment • Change characteristics of food product • Determine the micro flora associated with the product IMPLICIT PARAMETERS OR MICROBIAL INTERFERENCE • These are the result of the development of synergistic or antagonistic microbes • It can be said as the destruction of one organism by another species releasing H2 O2 , bacteriocin and other di-acetyl compounds.
- 12. • Synergistic: Production or availability of essential nutrients due to the growth of certain organisms, which allow the growth of another group which were otherwise unable to grow. • Antagonistic : Competition for essential nutrients, changes in pH value or redox potential or formation of antimicrobial substances.
- 13. TYPES OF SPOILAGE Two types of Spoilage: • Microbial spoilage • Non- Microbial Based on rate of spoilage: • Highly perishable – Meat, fish, poultry, eggs, milk, most fruits and vegetables. • Semi perishable – Potatoes, some apple varieties, nutmeats • Stable or non-perishable – Sugar, flour, dry beans
- 14. SPOILAGE OF FRUITS AND VEGETABLES • The organism responsible for taints are acid tolerant bacteria: – Lactobacillus spp. • Deterioration can be caused by action of animals, birds, bruising, wounding, cutting, freezing, dessication or other mishandling and growth of microorganisms; environmental conditions, contact with spoiled foods. • Microbial spoilage maybe due to: – Plant pathogens acting on stems, leaves, flowers or roots – Saprophytic organisms
- 15. • Types of spoilages: – Baterial soft rot • Caused by Erwinia carotovora, ferment pectins • Pseudomonas marginalis, Bacillus and Clostridium cause water soaked appearance, a soft, mushy consistency and bad odour. – Anthracnose • Caused by Collectotrichum lindemuthianum. • Spotting of leaves and fruits – Black mold rot • Caused by Aspergillus niger • Dark brown to black masses of spores of the mold termed as smut
- 16. • Rhizopus soft rot – Caused by species of Rhizopus – Soft and mushy rot – Cottony growth of mold forms black spots of sporangia covering the foods. • Alternaria rot – Caused by Alternaria tenuis – Greenish-brown to brown black spots • Fungal spoilage results in water soaked mushy areas, brown or cream coloured areas. Rots of juicy fruits result in leakage.
- 17. SPOILAGE OF CEREALS • Moisture content above 12 to 13 percent may cause spoilage of cereals • Little moisture cause mold growth and high moisture may cause growth of yeasts and bacteria. • Microbial content, physical damage and temperature are also some factors. • Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium are some common molds; produce mycotoxins. • Acetobacter spp, lactics and Coliforms, Micrococci and Bacillus are some species causing spoilage.
- 18. • Cause flour dough to develop an odour of acetic acid and esters • Ropiness of bread is common in home baked bread – Caused by Bacillus subtilis, B. licheniformis and other species – Due to the capsulation of Bacillus ropiness occurs. – First odour is evident, then discolouration and finally softening of the crumb with stickiness and stringiness. • Red bread is caused by the pigmented growth of Serratia marcescens. Molds such as Neurospora sitophila and Geotrichum aurantiacum can also cause red colouration.
- 19. SPOILAGE OF MILK • An excellent medium • Souring – caused by Streptococcus lactis, Enterococci, Lactobacilli, Micrococci • Gas production – caused by Coliform, Clostridium, Yeasts, Bacillus • Proteolysis – cause bitter taste, caused by Bacillus, Micrococcus, Proteus, Pseudomonas, Flavobacterium, Serratia. • Changes in colour and tastes
- 20. SPOILAGE OF MEAT • Raw meat is subject to spoilage by its own enzymes and microbial action. • Excessive autolysis can cause souring • Factors involving spoilage include – The greater gut load of animal – The physiological condition of the animal during slaughter as like fever, excited or fatigued. – Rapid cooling
- 21. SPOILAGE OF FISH • Spoiled by autolysis, oxidation or bacterial activity. • Under aerobic conditions – Surface slime • Caused by Pseudomonas, Moraxella, Alcaligens, Lactobacillus, Streptococcus, Leuconostoc,Bacillus,Micrococci. – Change in colour of meat pigments • Red colour, green,brown or grey
- 22. –Change in fats • Rancidity • Lipolysis • Oxidation of fats – Phosphorescence • Photobactererium spp growing on meat ―Surface colours due to pigmentation • Red spot caused by Serratia marcescens • Chromobacterium gives a greenish blue colour • Pseudomonas gives a bluish colour
- 23. • Micrococcus or Flavobacterium gives a yellowish colour. • Pencillium may cause greenish colour. • Cladosporium may cause black colour —Off odours and Off tastes • Taints, Souring, stale flavour can be caused as a result of bacterial and fungal growth.
- 24. SPOILAGE OF EGGS • Cracks, leaks, stained or dirty spots on exterior and blood clots, bloodiness, translucent spots in the interior are all signs of spoilage • Pseudomonas, Acinetobacter, Alcaligens, certain coliform bacteria. Proteus spp, Aeromonas, Serratia, Sporotrichum all cause rots in eggs
- 25. SPOILAGE OF CANNED FOODS • Chemical spoilage – Hydrogen swell – Discolouration of inside of the can – Cloudiness of liquors – Loss in nutritive value • Biological spoilage – Attacked by • Thermophilic and • Mesophilic bacteria
- 26. SPOILAGE CAN LEAD TO… • Food Poisoning • When someone gets sick from eating food or drink that has gone bad or is contaminated. • There are two kinds of food poisoning: poisoning by toxic agent or by communicable agent.
- 28. HOW CAN WE PREVENT? • FOOD PRESERVATION • What is food preservation? • Food preservation is the process of treating and handling food ,with an aim to stop or slow down its spoilage while maintaining its nutritional value, texture, and flavour. • Food preservation methods either kill microbes or prevent their growth.
- 29. Some methods are: 1. Boiling 2. Dehydration 3. Refrigeration & freezing 4. Canning 5. Using chemical preservatives 6. Using Salt, sugar, oil, or vinegar 7. Pasteurization
- 30. “Better pay the chef than the doctor!”