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TOPIC 1: FOOD BIO-DETERIORATION - Coggle Diagram
TOPIC 1: FOOD BIO-DETERIORATION
Bio deterioration
Bio deterioration is defined as the breakdown of food by agents of microbiological origin, either
directly or indirectly from products of their metabolism.
Food deterioration due to two reasons
1. Food Safety Problem
Involves issues of food contaminant with food hazards.
a. Biological Hazards
organisms that infect food such as bacteria, viruses, yeast, mold and parasites. These microorganisms can result in disease, unfavourable organoleptic (sensory) alterations in the food, or even both. The typical variables that make it possible for microorganisms to grow, such as the availability of food, acidity, temperature, time, oxygen, and moisture, are managed in processing in order to control biological factors.
b. Chemical Hazards
natural and man-made substances that may be present in the food at high concentrations resulting in food poisoning.
c. Physical Hazards
extraneous material that may fall into the food during harvesting and processing such as glass, metal and stones that may lead to cuts and other injury while eating.
2. Food Quality Problem
Include food safety issues but is much broader. The term “quality” is a loose term referring to the standards as determined by regulatory agencies, the manufacturer and the customer. Ultimately, once basic regulatory standards are met, the customer will determine what is “good quality” them
Bio deterioration agents
Enzymes and microorganism
Food is chemically broken down by enzymes, which can be found naturally or brought about by microbial action. The factors that may be used to reduce the amount of microorganisms as well as their growth circumstances are described. Due to the differences in the implications of adding the organisms to food and in approaches to destroying them, bacteria and fungus require different sub-sections.
Enzymes
complex globular proteins known as enzymes are present in living things and serve as catalysts for accelerating biological processes. Since enzymes are naturally found in food, they can catalyse processes that cause food deterioration. The production of food items can benefit from the use of enzymes, which are employed, for instance, in the production of cheese, the extraction of tomato and apple juice, and the clarifying of beverages. However, in order to maintain and increase the shelf life of foods, it is typically essential to inactivate enzymes (i.e., denature the proteins) present in food and on packing surfaces using heat or chemicals.
Microorganisms
All tiny, living creatures that are invisible to the unaided eye are referred to as microorganisms. They may be discovered everywhere, in the air, the water, the land, the plants, and the animals. Microorganisms can be highly significant in the breakdown of organic matter. However food preservation techniques try to stop this very process of organic matter degradation. The most popular technique for eliminating or reducing the amount of microorganisms found in meals and on packing surfaces is temperature. Five categories of temperature sensitivity are useful in defining the preferred temperature ranges for microorganism growth:
i. Psychrophilic (cold loving)
theorganisms can reproduce in chilled storage conditions, sometimes as low as 4◦C, although 12–18◦C is the preferred growth range. However, having evolved to survive in extremes of cold, these are the easiest to destroy by heat
ii. Psychrotrophic (cold tolerant)
optimum growth temperature is 20–25◦C but slow growth can be achieved down to 8–10◦C
iii. Mesophilic (medium range)
optimum growth temperature is 30–45◦C. These are of greatest concern with packaged foods because many spore-forming organisms such as yeast and mould species are contained within the mesophile category
iv. Thermophilic (heat loving)
the organisms have an optimum growth temperature of 45–60◦C. In general, these organisms are only of concern if packaged foods are intended for use in temperate climates where the ambient temperature is sometimes in this growth range
v. Thermoduric (heat enduring)
the organisms can survive above 70◦C, but cannot reproduce at these temperatures.
Bacteria
i. Pathogenic bacteria
Several bacteria need consideration when designing a packaging and processing line. Of primary concern from a public health perspective are those that produce toxins such as Clostridium botulinum, Listeria monocytogenes, Salmonella spp., Escherichia coli, Staphylococcus aureus, Bacillus cereus and Camplylobacter
ii. Beneficial bacteria
Bacteria have been used to beneficial effect in fermentation and preservation processes to extend the shelf life of certain foods. One example that has been exploited for many years is the deliberate introduction of lactic acid bacteria for the fermentation of milk to produce yoghurts. Lactic acid bacteria can be either bacilli or cocci and are facultatively anaerobic.
Fungi
a group of microorganisms that are found in nature on plants, animals and human beings. Different species of fungi vary a great deal in their structure and method of reproduction. Fungi may be single-celled round or oval organisms such as yeasts or threadlike multi-celled structures such as moulds. The mould threads may form a network, visible to the naked eye, as seen, for example, on foods such as bread and cheese
Food Deterioration
Food deterioration is defined as a process that makes a food unfit for ingestion and is brought on by the biochemical activity of the dominant microbial populations in the product. Food quality and shelf life are significantly impacted by food degradation brought on by spoilage microorganisms during storage and distribution, and pathogen microorganisms present in food can cause a number of diseases and intoxications. Foods' sensory qualities, nutritional content, safety, and visual appeal all deteriorate to differing degrees. It can also be referred to as food spoilage.
Bio- deterioration reaction
Enzymes
Mucor piriformis and Rhizopus species cause breakdown of texture in sulphite-treated strawberries as a result of a similar production of enzymes.
Byssochlamys, breakdown in texture of canned foods, particularly strawberries.
This is a heat resistant mould that requires temperatures in excess of 90◦C for several minutes to adequately destroy it.
Microorganism
Bacteria
Pathogenic bacteria
anaerobic conditions with available moisture, nutrients, and a pH of greater than 4.5 do C. botulinum spores begin to germinate.
The relatively mild heat treatment used in pasteurisation operations (usually 75-105°C) has less of an impact on product quality
Sterilisation methods, normally heated to temperatures between 115 and 135°C.
Critical to prevent the development of C. botulinum by preventing the pH of a high acid food from shifting to a low acid level due to spoilage organisms.
Beneficial Bacteria
Lactobacilli is to aid in the fermentation of milk into yoghurt.
Lactic acid bacteria are facultatively anaerobic and can be either bacilli or cocci.
The milk sugar lactose serves as source of energy during growth, and during fermentation, it is transformed into lactic acid. The acidity level rises until the yoghurt reaches a predetermined pH level and is ready to be packaged.
Once the fermentation is finished, the cells of lactic acid bacteria can be destroyed by heating to 70°C.
Fungi
Ascospores from moulds like Byssochlamys fulva are an exception.
These ascospores must be heated for a prolonged period of time at temperatures above 90 °C in order to produce a commercially sterile food in which they are the target organism.
Although a common source of B. fulva, strawberries would be harmed by this level of processing. Most yeast or mould cells usually die after just 5 to 10 minutes of heating at 60°C. The main reason for a spike in food spoiling outbreaks during the summer is that fungus like to grow at temperatures between 20 and 30 °C.
Non-enzymic biodeterioration
Dried potato and vegetables, fruit juices (both dried and concentrated) and wine.
Chemical reactions known as Maillard reactions.
The free amino groups of amino acids react with the aldehyde groupings of reducing sugars to develop furfuraldehyde, pyruvaldehyde, acetol, diacetyl, hydroxydiacetyl, and other sugar-degradation compounds. These compounds then react with amines to create macromolecules that resemble melanoid molecules (brown pigments).
Only successful way of inhibiting these reactions is by using sulphurous acid and sulphites. The levels of sulphur dioxide allowed in food products are strictly controlled by legislation and also by the amount that can be tolerated before the taste becomes unacceptable.
In the case of dried products, these are sulphited immediately after or during blanching. The use of sulphites for this purpose does not involve the antimicrobial protection for which these compounds are used in other applications.
Sulphite treatment of any fruit or vegetable intended for canning needs to be very tightly monitored in order to avoid the risk of severe accelerated internal de-tinning.
REFERENCE
Tucker, G. S. (2008). Food Biodeterioration and Preservation. Blackwell Publishing Ltd.
Joutey, N. T., Bahafid, W., Sayel, H., El Ghachtouli, N. (2013). Biodegradation: Involved Microorganisms and Genetically Engineered Microorganisms.