Spoilage of Perishable Food
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This document discusses the factors that cause spoilage in perishable foods. It outlines three main classes of foods based on their susceptibility to spoilage: non-perishable, semi-perishable, and perishable. The main causes of spoilage are biological factors like microbes and enzymes, and biochemical factors like the food's characteristics and storage conditions. Microbial spoilage can be caused by bacteria, yeasts, molds, insects, parasites, and rodents. The optimal conditions for microbial growth like temperature, oxygen levels, moisture, and duration of storage are described. Mechanical damage during handling can also introduce points of entry for microbes.
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Hurdle technology involves using two or more preservation methods together to inhibit microbial spoilage of foods. It allows for safer, stable foods without refrigeration. Common hurdles include reduced pH, increased salt content, reduced water activity, and heat processing. The hurdles work synergistically by disturbing the microbes' homeostasis. This technique is widely used in products like jam, fermented vegetables, meat, fish, and dairy. It improves safety and quality while reducing costs compared to using single preservation methods. However, some limitations exist in fully understanding and applying hurdle effects in practice.
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This document provides information on sausage making equipment, processes, safety considerations and sanitation. Key points:
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2) Grinders, choppers, stuffers and casings are used to grind, mix, fill and link sausages. Proper grinding plates and sharp blades are important for quality.
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Cereals and cereal products are susceptible to contamination and spoilage by microorganisms if not properly stored. Moisture content above 13% allows mold and bacterial growth. Common spoilage microorganisms include various bacteria and mold species. Proper preservation methods include low storage temperatures below 7°C, use of preservatives like propionates, and irradiation to reduce microbes. Mold growth is a major cause of bread spoilage and can be prevented through proper cooling, low humidity storage, and surface treatments. Ropiness of bread is caused by Bacillus species surviving baking and growing if conditions are favorable.
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Sugar has many uses in cooking beyond just providing sweetness. It acts as a preservative in jams and jellies, helps baked goods rise by feeding yeast, enhances flavors, adds color through caramelization, prevents spoilage of canned foods, and controls the texture of frozen desserts, candies, and more. There are various types of sugar used for different purposes, and sugar goes through several stages of crystallization when cooked to different temperatures that impact its properties.
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The document discusses the various factors that can cause food spoilage. It identifies three main types of causes: biological, chemical, and physical. Biological causes include the growth and activity of microorganisms like bacteria, yeasts, and molds. Chemical causes involve reactions with oxygen and light as well as chemical reactions within food constituents. Physical causes consist of improper holding temperatures and physical abuse. Specific spoilage factors are then discussed in more detail, such as spoilage due to microorganisms, carbohydrates, proteins, lipids, rancidity, oxidative changes, and enzymes. Oxidation is highlighted as a major problem that can produce undesirable biochemical changes in foods.
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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.
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
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.
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.
• 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.
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
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
• Types of spoilages: – Bacterial 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
• Rhizopus soft rot – Caused by species of Rhizopus – Soft and mu
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Spoilage of Perishable Food
- 1. SPOILAGE OF PERISHABLES MUNNA IYPE JOY BTF 11 222 2-7-2013
- 2. CLASSES OF FOODS ACCORDING TO EASE OF SPOILAGE i. Non-perishable/stable: Poor handling only causes spoilage(Sugar,Flour etc.) i. Semi-perishable:If properly handled,remains unspoiled for a fairly long period(Potato) i. Perishable:Spoiled readily unless special preservation methods emplyed(Fruits and Vegetables)
- 3. SPOILAGE(DEF) Any undesirabe change in normal state of food which makes it unfit for human consumption i.Biological factors ● Microbiological(bacteria, yeasts, moulds (most common)) ● Macrobiological(rodents, insects, birds, parasites) ii.Biochemical factors ● Action of Enzymes FACTORS OF SPOILAGE
- 4. iii.Characteristics and storage condition of food iv.Mechanical damage
- 5. 1.BIOLOGICAL FACTORS (i)MICROBIAL SPOILAGE ● Microbes present everywhere ● They may or may not cause spoilage (A)BACTERIA ● unicellular microbes ● Length is about 1μm and somewhat smaller dia ● Spores more resistant to processing conditions ● Cannot grow in acidic media(few exceptions)
- 6. (A)BACTERIAcontd.. ● Multiply by fission ● Temperature plays imp role in growth (optimum- 37ºc) ● Bacteria sensitive to acid- destroyed by boiling (for acidic fruits) ● Vegetables -non-acidic-121ºc ● Spores destroyed by heating 120ºc for 30-40 mins
- 7. GROUPS OF BACTERIA SHAPE ● Cocci-shperical ● Bacilli- rod shaped ● Vibrio- spiral OXYGEN REQUIREMENT ● Aerobes ● Facultative anaerobes ● Anaerobes
- 8. TEMPERATURE ● Mesophiles(below 38ºc) ● Thermophiles(45-60ºc) ● Psychrotrophes(refrigerated conditions) SOME SPOILAGE BACTERIA ● Acetobactor,Glucanobactor,Clostrisium,Propio nibacterium,Bacillus,Pseudomonas,Proteus.
- 9. (B)YEASTS ● Unicellular fungi ● Cell length 10μm and dia one third of length ● Multiplies by budding ● Yeast converts sugars to alcohol and CO2 ● Prefer low conc of sugar- grow best in 66% sugar & 0.5% acetic acid. ● Boiling destrys yeasts comletely ● Eg:Saccharomyces , Candida
- 10. (C)MOULDS ● Multicellular, filamentous fungi. ● Main parts are network of hyphae(mycelium)& spore. ● Thrive best in closed,moist,damp & dark situations ● Prefer sugar containing products(jams, jellies etc.) ● Acid medium favours growth and hence spoils pickles,juices ● Eg: Penicillium sp.,Aspergillus sp.,Mucor sp.
- 12. (i)MACROBIOLOGICAL SPOILAGE ● Caused by insects,parasites,rodents etc. ● Losses due to insects varies from 5-50% depending upon the care taken in field and during storage. ● Insects prevented or destryed by fumigating with: ● Ethylene oxide ● Methyl bromide ● Propylene oxide ● Indirect spoilage includes secretions,dead bodies,cuts they make in food etc.
- 13. ● Parasites like Entamoeba histolytica(amoebic dysentry) ● When raw human excrement is used as fertilizer for crops infestation happens. ● Infected water and poor hygeine also spreads parasite. ● Cooking kills these parasites. -- ● Rats also destroys food by consuming and contaminate it with urine,droppings which having disease causing bacteria (typhoid ,plague etc.)
- 14. 2.BIOCHEMICAL FACTORS ENZYME ACTION ● Changes in food during storage caused by (i)enzymes present in them enzymes present in banana cause ripening and if ripening is uncontroled it becomes too soft and unfit for consumption (ii)enzymes from microbes that contaminate food spoils the fruit. ● Enzymatic browning(phenolase oxidase)
- 15. Brownig of skin of banana Browning of cut apple ● Can be controlled by regulating temp,excluding moisture and air ● All enzymes inactivated at temp above 80ºc
- 16. 3.CHARACTERISTICS AND STORAGE CONDITION OF FOOD CHARACTERISTICS Char. Of a fruit tells which microbe will grow in it. (a)Composition ● Proteins degraded by proteolytic microbes like Pseudomonas,Proteus,Moulds ● Fats degraded by molds and some G-ve bacteria ● CHO degraded by Streptococcus, Leuconostac, Micrococcus (b)Acidity ● Acid(pH<4.5)-Molds,yeasts ● Non-acid (pH>4.5)-Bacteria
- 17. (C) Moisture ● Fruits deteriorate fast since it contains more moisture. ● Microbes require 13% free water in food ● Foods having more salt or sugar content do not support microbes. ● Bacteria inhibited-salt conc-5-15% ● Yeast tolerate >15% salt ● Sugar- 65-70%- Moulds - 50%- bacteria,yeasts
- 18. STORAGE CONDITIONS (a) Temperature ● The rate of a reaction doubles at 10ºc increase ● Several fruits and vegetables deteriorate even at refr. Temperature(4ºc) ● Food stored at -18ºc remains free from microbial growth. ● Foods stored at room temperature undergo mesophilic spoilage
- 19. (b) Oxygen ● Continuous contact with air causes destruction of colour,flavour, vit-A,vit-C. ● Moulds will not grow in anaerobic conditions. ● Hence vacuum packaging,deaeration,nitrogen flushing, oxygen absobing chemicals prevent mould. (C)Light ● Light destroys vit-B2,A and C ● Protecting food by impervious packaging ● Containers that screen spcific wavelength.
- 20. (d)Duration ● All deteriorating factors are time dependent. ● Time deteriorates foods except cheese,wine and fermented foods. 4. MECHANICAL DAMAGE ● During picking, cleaning , grading etc. damage occurs. ● Injured spots becomes the entrance point of microbes causing spoilage. ● Eg: crown rot in banana,pedicel rot in pine apple, blue mould in apple ● Removal of scratched or damaged fruits,fungicide treatment (thiabendazole,benomyl,sodium orthophenylphenate) reduce after effects of mech. damages.
- 22. REFERENCE ● R.P. Srivastava,Sanjeev Kumar,2006(3),Fruit and Vegetable preservation priciples and practices, International Book Distributing Co.,Lucknow,p61-72
- 23. Thank You