This document discusses food spoilage, including definitions, types, causes, and examples of spoilage in different food categories like meat, dairy, fruits and vegetables. It defines food spoilage as any changes that make food unacceptable for consumption. Spoilage can be caused by physical injury, enzymatic degradation, or microbial activity. The main types are physical, chemical, and microbial spoilage. Microbial spoilage is the most common and is caused by the growth of microorganisms like bacteria, yeasts and molds. Specific examples of spoilage in foods like meat, milk, eggs and produce are provided.
Microbial spoilage by Anaerobic Microorganisms pose higher risks in canned foods. This presentation discuss the microbial spoilage of canned foods by various group of microbes
INTRODUCTION:
BREAD is a dietary product obtained from the fermentation and the subsequent baking of a dough mainly made of cereal flour and water, made in many different ways and sometimes enriched with typical regional ingredients.
Ingredients of bread:
Flour is the bulking ingredient of bread, it forms the structure of the product,contains gluten which helps to form an elastic stretchy dough.
Yeast is a raising agent. Yeast produces gases to make the bread rise.
Salt is required to bring out flavour in the bread, it is used in small quantities.Too much of this ingredient will stop the yeast from growing.
Yeast needs energy to grow. Sugar provides the food for the yeast; it is needed to help the yeast grow.
Water is used to bind the flour together and helps to form the structure of the bread.
Fats or oils improve the texture of the bread, preventing it from going stale quickly.
Starter culture:
Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae, which is the same species (but a different strain) commonly used in alcoholic fermentation which is called brewer's yeast.
Bread Making Process
Mixing has two functions: to evenly distribute the various ingredients and allow the development of a protein (gluten) network to give the best bread possible.
Once the bread is mixed it is then left to rise (ferment).
Any large gas holes that may have formed during rising are released by kneading.
Moulding the dough into desired loaf shape.
During the final rising the loaf fills with more bubbles of gas, and once this has proceeded far enough they are transferred to the oven for baking.
The loaf is then placed in a preheated oven to bake. Such a high heat will kill the yeast, thus stopping its process of rising and growth.
The whole loaf is cooled to about 35°C before slicing and wrapping can occur without damaging the loaf.
Types of Bread
1. White Bread
2. Brown Bread
3. Wholemeal bread
4. Rye bread
Apart from above there are several types like Crisp bread, Flatbread is often simple, made with flour, water, and salt.
Microbial spoilage
Molds are the primary spoilage organisms in baked goods, with Aspergillus, Penicillium, and Eurotium being the most commonly isolated genera.
Quality control
As a foodstuff, bread is subject to stringent government food processing regulations, including, but not limited to the percent of additives allowed, sterilization of plant equipment, and cleanliness of plant workers. In addition to adhering to these regulations, processors control the quality of their products to meet consumer expectations by installing checkpoints are various stages of the processing.
Fermentation in food processing is the process of converting carbohydrates to alcohol or organic acids using microorganisms—yeasts or bacteria under anaerobic conditions.
Or
Any metabolic process that releases energy from a sugar or other organic molecule, does not require oxygen or an electron transport system, and uses an organic molecule as the final electron acceptor
Fermentation usually implies that the action of microorganisms is desired.
The science of fermentation is known as zymology.
in microorganisms, fermentation is the primary means of producing ATP by the degradation of organic nutrients anaerobically
Canning has been a preservation process since ages. This presentation gives a brief description about the process and some of the problems related to it.
Micro-organisms important in Food Microbiology. Bacteria, Yeast, MoldsSt Xaviers
Here is a ppt on food microbiology. consisting information for molds, bacteria and yeast. information on types of good and bad components in each category.
Microbial spoilage by Anaerobic Microorganisms pose higher risks in canned foods. This presentation discuss the microbial spoilage of canned foods by various group of microbes
INTRODUCTION:
BREAD is a dietary product obtained from the fermentation and the subsequent baking of a dough mainly made of cereal flour and water, made in many different ways and sometimes enriched with typical regional ingredients.
Ingredients of bread:
Flour is the bulking ingredient of bread, it forms the structure of the product,contains gluten which helps to form an elastic stretchy dough.
Yeast is a raising agent. Yeast produces gases to make the bread rise.
Salt is required to bring out flavour in the bread, it is used in small quantities.Too much of this ingredient will stop the yeast from growing.
Yeast needs energy to grow. Sugar provides the food for the yeast; it is needed to help the yeast grow.
Water is used to bind the flour together and helps to form the structure of the bread.
Fats or oils improve the texture of the bread, preventing it from going stale quickly.
Starter culture:
Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol. Baker's yeast is of the species Saccharomyces cerevisiae, which is the same species (but a different strain) commonly used in alcoholic fermentation which is called brewer's yeast.
Bread Making Process
Mixing has two functions: to evenly distribute the various ingredients and allow the development of a protein (gluten) network to give the best bread possible.
Once the bread is mixed it is then left to rise (ferment).
Any large gas holes that may have formed during rising are released by kneading.
Moulding the dough into desired loaf shape.
During the final rising the loaf fills with more bubbles of gas, and once this has proceeded far enough they are transferred to the oven for baking.
The loaf is then placed in a preheated oven to bake. Such a high heat will kill the yeast, thus stopping its process of rising and growth.
The whole loaf is cooled to about 35°C before slicing and wrapping can occur without damaging the loaf.
Types of Bread
1. White Bread
2. Brown Bread
3. Wholemeal bread
4. Rye bread
Apart from above there are several types like Crisp bread, Flatbread is often simple, made with flour, water, and salt.
Microbial spoilage
Molds are the primary spoilage organisms in baked goods, with Aspergillus, Penicillium, and Eurotium being the most commonly isolated genera.
Quality control
As a foodstuff, bread is subject to stringent government food processing regulations, including, but not limited to the percent of additives allowed, sterilization of plant equipment, and cleanliness of plant workers. In addition to adhering to these regulations, processors control the quality of their products to meet consumer expectations by installing checkpoints are various stages of the processing.
Fermentation in food processing is the process of converting carbohydrates to alcohol or organic acids using microorganisms—yeasts or bacteria under anaerobic conditions.
Or
Any metabolic process that releases energy from a sugar or other organic molecule, does not require oxygen or an electron transport system, and uses an organic molecule as the final electron acceptor
Fermentation usually implies that the action of microorganisms is desired.
The science of fermentation is known as zymology.
in microorganisms, fermentation is the primary means of producing ATP by the degradation of organic nutrients anaerobically
Canning has been a preservation process since ages. This presentation gives a brief description about the process and some of the problems related to it.
Micro-organisms important in Food Microbiology. Bacteria, Yeast, MoldsSt Xaviers
Here is a ppt on food microbiology. consisting information for molds, bacteria and yeast. information on types of good and bad components in each category.
Meat is one of the major food consumed in the temperate region of the world. Hence it is required to preserve meat from microbial spoilage in order to increase its shelf life, to facilitate long term transport and storage. The first step is to understand the process of meat spoilage, then study the effect of spoilage and finally to incorporate appropriate processing techniques to enhance the shelf life of meat, there by achieving customer satisfaction and also contributing towards food security.
Revisión de Fiebre Amarilla que trasciende desde la historia milenaria de esta enfermedad, nos da un enfoque amplio de su concepto, características epidemiológicas, criterios clínicos de aproximación diagnóstica y terapeútica.
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
This ppt has information about food spoilage and contamination, which cause disease in human also tell about the type of contamination and food spoilage and route of transmission in human by which it spread its disease in human
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
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Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
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2. INTRODUCTION
Food spoilage can be defined as:
• any changes in the visual, smell and texture of food that makes it
unacceptable for consumption.
Or
• is the process in which food deteriorates to the points it is not
edible to humans or its quality of edibility becomes reduced.
9. • Various bacteria can be responsible for the
spoilage of food.
• When bacteria breaks down the food, acids and
other waste products are created in the process.
•
• While the bacteria itself may or may not be
harmful, the waste products may be unpleasant
to taste or may even be harmful to one's health.
10. • Yeasts can be responsible for the
decomposition of food with a high sugar
content.
• The same effect is useful in the production of
various types of food and beverages, such as
bread, yogurt and alcoholic beverages.
11. • Some spoiled foods are harmless to eat, and may simply be
diminished in quality.
• But foods exhibiting certain types of spoilage may be
harmful to consume. Uncooked or under-cooked animal
flesh that spoils is typically quite toxic, and consumption
can result in serious illness or death.
• The toxic effects from consuming spoiled food are known
as "food poisoning", and more properly as"foodborne
illness”.
12. 12
Visible growth
Gas production
Slime
Off-flavours
Microbial spoilage – how does it manifest
itself?
13. Sequence of events in food spoilage
Microorganisms have to get into the food
from a source or more
↓
Food environment should favour the growth of microbes
↓
Food need to be stored under the growth condition
for a sufficient length of time
• To allow sufficient number necessary to cause spoilage
or changes in food.
• To allow the produced enzyme to spoil the food.
14. Chemical changes caused by micro
organisms
Degradation of carbohydrates
Degradation of N- compounds
Degradation of lipids
Pectin hydrolysis
15. • Inadequate storage temperatures
• Prolonged storage times
• Improper ventilation
• Cross contamination
• Excessive delays between receiving and storing
Common Causes of Food Spoilage
16. Spoilage Signs
• Odor:
– Breakdown of proteins (putrefaction)
e.g. “rotten egg” smell
• Sliminess
-due primarily to surface accumulation of
microbial cells
-also be a manifestation of tissue
degradation
• Discoloration
– Mold on bread, blue and green mold
on citrus fruit and cheese
17. Spoilage Signs…
• Souring
– Production of acid
e.g. sour milk from production of lactic
acid
• Gas formation
– Meat becomes spongy
– Swollen or bubbling packages and cans
18. Classification of food by ease of
spoilage
Foods can be classified into three groups based on
ease of spoilage:
I. Stable or non perishable foods.
Foods which do not spoil unless handle carelessly.
Example: Sugar, flour and dry beans.
19. II. Semi perishable foods.
If these foods are properly handled and stored, they will
remain unspoiled for a fairly long period.
Examples: potatoes, apples and nuts.
20. III. Perishable foods.
This group includes most of our important daily foods that
spoil readily unless special preservative methods are used.
Examples: meats, fish, milk, vegetables, eggs and etc.
23. Meat spoilage…
Sources of contamination
• Cutting board contamination
• Conveyor belts
• Temperature
• Delay between storage and distribution
• Fecal contamination from intestines
24. Meat spoilage…
• Storage temperature is the single most
important control factor for meat spoilage.
• Several genera of molds grow on the surface of meat
and can cause spoilage like
Penicillium, Mucor, Cladosporium, Alternaria, but
cannot grow on meat stored below 5oC.
25. Meat spoilage…
• Meat spoilage is characterized by the
appearance of off odors and slime, which are
manifest when surface loads
exceed 107 CFU/cm2.
• The slime is due to the accumulation of
bacterial cells.
26. Meat spoilage…
• Interestingly, meat spoilage (including poultry and
fish) occurs without any significant breakdown of
the primary protein structure.
• Instead, spoilage bacteria utilize glucose, free amino
acids or other simple nitrogenous compounds to
attain population of about 108 CFU/cm2, at which
point the organoleptic quality of the meat will clearly
reveal it is spoiled.
28. Meat Spoilage
• Whole Meats:
The microflora of fresh meat is
composed primarily of:
1- Gram negative aerobic rods such
as:
– Pseudomonas spp.
– P. fragi, P. lundensis and P. fluorescens
– Acinetobacter
– Psychrobacter immobilis
29. Meat spoilage…
2- Bacillus and clostridia
(e.g. C. perfringens) are also common on all types of
meat.
• Although subsurface portions of meat are generally sterile,
some parts such as lymph nodes may be heavily
contaminated.
• Mechanical disruption of the tissue during processing can
distribute microorganisms from the meat surface throughout
the product.
30. Meat spoilage…
• Ground Meats:
Same MO as whole meats, but always have higher microbial
loads. Why?
• greater surface area which gives microbes better access to the food
and also traps air to favor the growth of gram-negative, aerobic
bacteria like Pseudomonas spp.
• every handling or processing (storage utensils, cutting knives,
grinders) step can contribute additional contamination to the final
product.
• one heavily contaminated piece (e.g. a lymph node) can
contaminate an entire lot when they are ground together.
31. Meat Spoilage
• Vacuum – packed meats
-not all O2 is removed during packaging but
residual is consumed by respiration of
aerobic MO and the tissue itself.
- results in increased CO2 levels and thus get
a longer shelf life.
The microflora shifts from predominantly G-
aerobes to G+ anaerobes and
microaerophilic lactic acid bacteria (LAB)
(like Lactobacillus,Carnobacterium and
Leuconostoc).
32. Meat Spoilage
• if nitrites have been added to the vacuum packaged
meat (e.g. to inhibit C. botulinum in hams, bacon),
LAB domination is even more pronounced
•
• In general, vacuum packaged meats are considered
very safe foods and free from most pathogenic
species of bacteria.
33. Spoilage in vacuum packaged meats is manifest
by:
1. Slime development due to overgrowth of
microbe.
2. Greening caused by microbial production of
H2O2 or H2S.
• H2O2 production in meat has been associated
with several types of lactic acid bacteria
(primarily Lactobacillus)
34. Meat Spoilage
3. Off odors which result from:
1. the release of short chain fatty acids
2. the production of volatile compounds like acetoin,
diacetyl and H2S (and many other compounds,
depending on the dominant spoilage bacterium).
35. Meat Spoilage
The type of spoilage bacteria that will dominate is influenced
by several factors that include:
1. Is the meat product is raw or cooked?
-Cooked products have a higher pH (>6.0) which may allow growth of
G- facultative anaerobic pathogens like Yersinia enterocolitica.
-Raw products have a pH of about 5.6 which favors lactic acid bacteria,
esp. Lactobacillus, Carnobacterium, and Leuconostoc.
2. Nitrite concentration in meat.
-High nitrite conc. favors lactic acid bacteria.
-Low nitrite levels may allow growth of Brochothrix thermosphacta (G+
rod, fac anaer, growth @ 0-30oC from pH 5.0-9.0 catalase+).
36. Meat Spoilage
• Processed meats (hot dogs, sausage and luncheon
meats)
• These products are composed of a variety of blended
ingredients, any of which can contribute microorganisms to
the food.
• Yeasts and bacteria are the most common causes of spoilage,
which is usually manifest in 3 ways:
37. A. Slimy spoilage
Like other meat products, this occurs on the surface and is
caused by the buildup of cells of yeasts, lactobacilli, enterococci
or Brochothrix thermosphacta.
Washing the slime off with hot water can restore the product
quality.
B. Sour spoilage.
Results from growth of lactic acid bacteria (which originate
from contaminated ingredients like milk solids.
These organisms ferment lactose and other CHOs in the
product and produce organic acids. Taste is adversely affected
but the product is not harmful if eaten.
38. C. Greening
due to H2O2 or H2S production. Because greening indicates
more extensive product breakdown, it is not recommend
eating green wieners.
39. Poultry and egg spoilage
Poultry
a. general trends are the same as other fresh meats
b. whole birds have lower counts than cut-up parts
c. additional processing steps add to the microbial load
-When poultry is in the advanced
stages of spoilage, the skin will
often fluoresce under
UV because so many
fluorescent pseudomonads are present.
40. • Off odors generally appear before sliminess develops.
The same bacteria can produce visceral taint, a
condition manifest by off odors in the abdominal cavity
of poultry.
Point to remember:
During the initial stages of spoilage, the skin supports
bacterial growth better than does the tissue (which
remains essentially free of bacteria for some
time). Thus, the skin can sometimes be removed to
salvage the food.
41. Eggs
• Eggs have several intrinsic parameters which help to
protect the nutrient-rich yolk from microbial attack.
•
• These include the shell and associated membranes, as
well as lysozyme and a high pH (>9.0) in the white.
• Freshly laid eggs are generally sterile, but soon become
contaminated with numerous genera of bacteria.
42. • Eventually, these MO will penetrate the eggshell and
spoilage will occur.
• Pseudomonads are common spoilage agents, but
molds like Penicillium and Cladosporium sometimes
grow in the air sac and spoil the egg.
43. Fish Spoilage
a. Fish have high nitrogen content but no carbohydrate.
b. The microbial quality of fish and especially shellfish is heavily
influenced by the quality of the water from which they were
harvested.
• Unsanitized processing steps are principal culprits in fish products
with high microbial loads.
• In general, frozen fish products have lower counts than fresh
products.
• Bacteria on fresh fish are concentrated on the outer slime, gills and
intestine.
44. • Spoilage of salt- and freshwater fish occurs in similar
ways; the most susceptible part of the fish to spoilage
is the gill region.
• and the best way to detect spoilage in fresh fish is to
sniff this area for off odors produced by Pseudomonas
and Acinetobacter-Moraxella bacteria.
• The odors include ammonia, triethylamine, H2S and
other compounds.
• If fish are not eviscerated quickly, bacteria will move
through the intestinal walls and invade the meat that
lies next to the abdominal cavity.
45. • Spoilage of crustaceans (shrimp, lobsters, crabs and crayfish)
is similar, but these products have some CHO (0.5%) and more free amino
acids so spoilage can occur more rapidly.
• Mollusks (oysters, clams, mussels, squid and scallops)
• have more CHO (3-5%) and less nitrogen than either fish or shellfish.
Microflora of mollusks can vary a great deal depending on the quality of the
water from which they were harvested.
• Shellfish are filter feeders and can be expected to contain almost any
microorganism or virus that occurs in the water where they were obtained.
• If these products were taken from clean waters, then the
usual Pseudomonas and Acinetobacter-Moraxella types of spoilage bacteria
dominate.
47. Milk
Milk is a very rich medium
• Raw milk
flora may include:
a. All MO found on the cow hide (which incl. soil and fecal bacteria),
udder, and milking utensils
b. Can include G-, G+, yeasts and molds.
• When properly handled and stored, the flora of pasteurized milk is
primarily G+ bacteria.
• Psychrotropic pseudomonads are common in bulk stored raw milk
• produce heat stable enzymes that can reduce milk quality and shelf
life.
48. • Pasteurization kills most G- (incl. Pseudo.), yeasts
and molds.
• some G- enzymes, thermotolerant G+ bacteria and
spores survive
• Psychrotropic Bacillus spp. are also common in raw
milk.
49. • Pasteurized fluid milk
spoiled by a variety of bacteria, yeasts and molds.
a. milk is more frequently spoiled by aerobic
sporeformers such as Bacillus, whose proteolytic
enzymes cause curdling.
• c. Molds may grow on the surface of spoiled
milk, but the product is usually discarded before
this occurs.
50. • Butter
high lipid content and low aw make it more
susceptible to surface mold growth than to bacterial
spoilage.
• Some pseudomonads can be a problem; “surface
taint” -putrid smell, caused by the production of
organic acids (esp. from P. putrefaciens).
• Rancidity due to butterfat lypolysis caused by P.
fragi are common.
51. • Cottage cheese
can be spoiled by yeasts, molds and bacteria.
The most common bacterial spoilage is “slimy
curd” caused by Alcaligenes spp. (G- aerobic
rod bound in soil, water, and intestinal tract of
vertebrates).
• Penicillum, Mucor and other
fungi also grow well on cottage cheese
and impart stale or yeasty flavors.
52. • Ripened Cheeses
(1) low aw
(2) low pH
(3) high salt inhibit most spoilage microorganisms
except surface mold growth.
53. • Spores of C. butyricum, C. sporogenes and others can
germinate in cheeses (e.g. Swiss) with intrinsic
properties that are less inhibitory (e.g. lower salt,
higher pH).
• These organisms may metabolize citrate, lactose,
pyruvate or lactic acid and produce butyrate or
acetate plus CO2 or H2 gas which “blows” the cheese.
55. Vegetables
Typical composition:
-88% water
-8.6 % CHO. Includes readily available mono- and disaccharides like
glucose and maltose, as well as more complex oligosaccharides,
which are available to fewer types of microorganisms.
-1.9% protein
-0.3 % fat
-0.84 % minerals
-also contain fat and water soluble vitamins and nucleic acids (<1%).
-pH of most veggies is around 6.0; within the growth range of many
bacteria.
56. Vegetables
• Vegetables are a good substrate for yeasts, molds or
bacteria
• It is estimated that 20% of all harvested fruits and
vegetables for humans are lost to spoilage by these
microorganisms.
• Because bacteria grow more rapidly, they usually out-
compete fungi for readily available substrates in
vegetables.
• As a result, bacteria are of greater consequence in the
spoilage of vegetables with intrinsic properties that support
bacterial growth (favorable pH, Eh).
57. Vegetables
• Microflora of vegetables is primarily composed
of:
– G+ bacteria like lactic acid bacteria (e.g.
leuconostocs, lactobacilli, streptococci.
– Coryneforms and staphylococci (the latter
coming from the hands of employees during
processing.
• Staphylococci are usually unable to proliferate but cross-
contamination can introduce them into other foods where growth
conditions are more favorable.
58. Vegetables
• Soft rot
a. One of the most common types of bacterial spoilage.
b. caused by Erwinia carotovora and sometimes
by Pseudomonas spp., which grow at 4oC
• Softening can also be caused by endogenous enzymes.
59. Vegetables
Mold spoilage
a. In vegetables where bacterial growth is not favored
(e.g. low pH), molds are the principal spoilage agents.
b. Most molds must invade plant tissue through a surface
wound such as a bruise or crack.
c. Spores are frequently deposited at these sites by insects
like Drosophila melanogaster, the common fruit fly.
d. Other molds like Botrytis cinerea, which causes grey
mole rot on a variety of vegetables, are able to penetrate
fruit or vegetable skin on their own.
60. Vegetables
The microflora of vegetables will reflect:
a. the sanitation of processing steps.
b. the condition of the original raw product.
- Soil-borne MO such as clostridia are common on
raw vegetables, and some species, like C.
botulinum, are of such great concern that they
are the focus of processing steps designed to
destroy MO.
61. Vegetables
Sources of Contamination
1. Surface contamination – Soil, water, air, human
pathogens from manure (night soil)
2. Harvesting - hand picking vs. machines
3. Packaging: containers reused
4. Markets – handling, cross-contamination
62. Fruits
Average composition
-85% water
-13% CHO
-0.9% protein (a bit low on nitrogen sources)
-0.5% fat
-0.5% ash
-trace amounts of vitamins, nucleotides, etc.
-less water and more CHO than veggies
-low pH (1.8-5.6)
63. Fruits
• Like vegetables, fruits are nutrient rich substrates
but the pH of fruits does not favor bacterial
growth. As a result, yeasts and molds are more
important than bacteria in the spoilage of fruits.
a. Several genera of yeasts can be found on fruit.
b. Because these organisms grow faster than molds, yeast often
initiate fruit spoilage.
c. then molds finish the job by degrading complex
polysaccharides in cell walls and rinds.
64. Fruits
Specific Spoilage Organisms:
1. Blue rot – Penicillium (fruits)
2. Downy mildews – Phytophora, large
masses of mycellium (grapes)
3. Black rot – Aspergillus (onions)
4. Sour rot – Geotrichum candidum
65. Cereal and Bakery Goods
• These products are characterized by a low
aw which, when stored properly under low
humidity, restricts all MO except molds.
• Rhizopus stolonifer is the common bread
mold, and other species from this genus spoil
cereals and other baked goods.
• Refrigerated frozen dough products have
more water and can be spoiled by lactic acid
bacteria.
66. Fermented Foods and Beverages
• The low pH or ethanol content of these
products does not allow growth of pathogens,
but spoilage can occur.
67. Fermented Foods and Beverages
• Beer and wine (pH 4-5) can be spoiled by yeasts and
bacteria.
• Bacteria involved are primarily lactic acid bacteria like
lactobacilli and Pediococcus spp.
• and (under aerobic conditions) acetic acid bacteria
like Acetobacter and Gluconobacter spp. Acetic acid
bacteria convert ethanol to acetic acid in the presence
of oxygen.
• The anaerobic bacterium Megasphaera cerevisiae can
also spoil beer by producing acid and H2S.
68. beer
• Spoilage in packaged beer is often due to
growth of the yeast Saccharomyces
diastaticus, which grows on dextrins that
brewers yeast cannot utilize.
• In either case, spoilage by yeasts results in
the development of turbidity, off flavors and
odors.
69. Wines
• Candida valida is the most important spoilage yeast
in wine.
• can also be spoiled by lactic acid bacteria which are able to
convert malic acid to lactic acid (malo-lactic
fermentation). This reduces the acidity of the wine and
adversely affect wine flavor.
• In some areas (e.g. Northwest), wine grapes have too much
malic acid so this fermentation is deliberately used to
reduce the acidity of grape juice that will be used for wine.
70. • Yeasts, molds and lactic acid bacteria can also
spoil fermented vegetables such as sauerkraut
and pickles, as well as other acid foods like
salad dressings and mayonnaise.
71. • Spoilage in fermented vegetables is
often manifest by off odors or
changes in the color or texture
(softening) of the product.
• In mayonnaise or salad dressing,
the first signs of spoilage are usually
off odors and emulsion separation.