Understanding Food Spoilage

Food spoilage refers to the deterioration in the quality of food due to various physical, chemical, biochemical, and microbiological processes. The effects of spoilage can manifest in different ways, making food visually unappealing, emitting unpleasant odors, or altering its taste. Visual signs may include discoloration, the formation of colonies, or structural breakdown, often leading to container swelling.

Microbial growth is a key contributor to food spoilage, leading to undesirable changes in texture, flavor, and aroma. Pathogenic microorganisms pose a significant safety risk in food processing, highlighting the importance of effective preservation methods.

Several factors influence the rate and extent of food spoilage. Temperature control is crucial; refrigeration slows microbial growth, extending the shelf life of perishable items. pH levels, water activity, exposure to oxygen, and light also impact spoilage rates. Additionally, the presence of available nutrients or chemicals in the food can accelerate deterioration processes.

Advancements in food science have deepened our understanding of spoilage mechanisms. For instance, modern techniques like modified atmosphere packaging help maintain product freshness by controlling gas composition around the food.

In conclusion, food spoilage is a complex phenomenon influenced by various factors. Understanding these processes is vital not only for maintaining food quality but also for ensuring food safety and reducing food waste in today's globalized food supply chain.
Understanding Food Spoilage

Food adulteration

Adulteration of food is the process of adding unwanted substances to the food, with similar appearance/color for making profits which makes that food product fails to meet the legal standards. This act of spoiling the nature and quality of food items is considered food adulteration.

Adulterants are the substance or poor-quality products added to food items for economic and technical benefits. Addition of these adulterants reduces the value of nutrients in food and also contaminates the food, which is not fit for consumption.

Adulteration is very common today and the most adulterated food product is milk. Other common food items which are adulterated are tea/coffee, vegetables, sweets, wheat and other food grains, honey, spices, butter and cream, ice cream.

Food adulteration may be categorized into two separate groups, namely, incidental and intentional adulteration. Incidental adulteration occurs when adulterants are found in food due to negligence, ignorance or lack of proper facilities. For example, packaging hazards like larvae of insects, droppings, pesticide residues, etc.

Intentional adulteration involves the deliberate addition of inferior materials to a food to heighten appearance qualities and to gain greater profits.

The estimated economic loss of food due to adulteration is 30–40 billion dollars per year.
Food adulteration

Food quality: Off-odors

Odor is complex both because of the large number of compounds that contribute to it and because it involves a subjective human response. Odorants have a major importance for the evaluation of food.

Pleasant aromas become off-odors when they exist in environments where they should not. Off-odors can cause severe problems in foods, leading to economic losses due to product recalls, reduced consumer confidence and to potentially a tarnished brand image.

Common causes for off-odor problems including: flavor scalping, spoilage, product formulation interactions, introduction of new vendors and ingredients, packaging failures/changes, production issues/changes, warehouse and transportation storage issues.

Off-odors in foods may result from oxidation, light-catalyzed reactions, nonenzymatic browning, chemical reactions and interactions among food constituents, enzymatic reactions and microbial spoilage.

Many interactions between food components, e.g., catalysis by metal ions or on surfaces, radical and redox reactions may influence the release, formation and transition of odorants. An off-odor makes products look bad, regardless of whether a true health risk exists.

Bacterial spoilage of dairy foods is manifested by the presence of a wide variety of metabolic by-products, causing off-odors and flavors, in addition to visible changes in color or texture. Because of the perishability of milk and the nature of milk production and handling procedures, the development of off-odors is not uncommon.

Off-odors are occasionally reported in bottled product. The more common off odor issues result from whisky being transported and stored in unsuitable environmental conditions. For example; transit and storage close to very smelly chemicals can result in odor ingress into the bottle.
Food quality: Off-odors

What is food energy value?

The energy value of foods is currently expressed in Kcalories (Kcal) and in Kjoules (Kj), the conversion factor being 4.184 to obtain Kjoules from Kcalories. This dual system emerged from a recommendation of the International Union of Nutritional Sciences to express the energy content of foods also in joules, since they represent a more scientifically correct unit to describe biological work, even though the use of calories is still predominant.

The chief food sources of energy to the human body are fat, carbohydrate, and protein. Fats and carbohydrates contain carbon and hydrogen which can be oxidized to their end products, CO2 and H2O, both in the bomb calorimeter and in the body. In addition, protein contains nitrogen. This nitrogen together with some carbon and hydrogen leaves the body chiefly in the form of urea.

The energy yielding food factors are:
-Carbohydrates: banana, breadfruit, jackfruit, plantain, dates, prunes, raisin
-Proteins and amino acids: nuts, dried apricot, fig
-Fats: avocado, olive, nuts

The energy value of foods can be expressed in terms of kilo calories (KCal) or megajoules (MJ).
*Kilo Calorie: One kilo calorie is the quantity of heat required to to raise the temperature of 1kg of water through 10C. It is one thousand times the small calorie used in physics measurements.
*Mega Joule : One kilo calorie equals 4.186 kilo joules. Hence thousand kilo calorie equals 4.186×103kilo joules or 4.186 mega joules.

Most of the fundamental work on the energy value of foods was carried out by the pioneer scientists Rubner (in Germany) and his pupil Atwater (in USA) at the end of the nineteenth century. Rubner measured the heats of combustion of a number of different proteins, fats, and carbohydrates in a bomb calorimeter and also studied the heat of combustion of urine passed by a dog, a man, a boy, and a baby.
What is food energy value?

Food aroma: sense by taste and smell

Flavor is usually divided into the subsets of taste and smell, which are perceived in the month and the nose, respectively.

Smell is an elementary parameter in the food valuation. Aroma (or smell or odor) is the sensation perceived when volatile compounds are sniffed through the nose.

What is a volatile compound? A small molecule which has a high tendency to evaporate. Volatiles are naturally produced by plants (flowers, fruits, vegetables, herbs…) and animals. They can also be made artificially (by chemical reactions designed for their production).

Food aroma is felt by sense of taste and smell by awaking the receptors of taste on the tongue and by smell receptors in the nasal cavity, that send information to the central nervous system and give a flavor sensation.

A natural aroma, smell or odor is typically made up of tens or sometimes hundreds of different volatile compounds. In general, the aroma of a food consists of many volatile compounds, only a few of which are sensorially relevant. A first essential step in aroma analysis is the distinction of the more potent odorants from volatiles having low or no aroma activity.

Typically, food aroma is an equilibrium mixture of aroma compounds. All aroma compounds are relatively small (400 Da), usually organic compounds. A vast array of compounds may be responsible for the aroma of the food products, such as alcohols, aldehydes, esters, dicarbonyls, short to medium-chain free fatty acids, methyl ketones, lactones, phenolic compounds and sulphur compounds.

The release of aroma compounds from foods is determined by the partition coefficient between the air phase and food matrix and, in the retronasal case, by the partition coefficient between the water phase (saliva) and the food matrix.

Food aroma is very sensitive to the processing and storage conditions. Flavor loss as well as off-flavor development is a problem for the food industry, and could be limited by the encapsulation of the volatile ingredients prior to their use.

Of the major food constituents, carbohydrates have generally the greatest influence on aroma compound release and retention. Carbohydrates are widely used in the food industry as sweetener, thickeners, stabilizers and gelling agents in products such as ice cream, beverages, jellies and sauces.
Food aroma: sense by taste and smell

Biomolecular Engineering

Biomolecular engineering is an emerging field of academic research and industrial practice. Biomolecular engineering was defined by National Institute’s of Health for a December 1992 meeting as “…research at the interface of chemical engineering and biology with an emphasis at the molecular level.”

Biomolecular engineering can be used to purposefully manipulate biomolecules, such as peptides, proteins, nucleic acids and lipids, within the framework of the relations among their structures, functions and properties.

Molecular biology is principally concerned with the storage, replication, and use of information. A living cell must process information from the external world and act upon it to ensure survival and replication of the organism.

Recent advances in biomolecular engineering, such as genetic engineering, DNA and RNA engineering, protein engineering, site-specific chemical and enzymatic conjugation technologies, self-assembly technology and massive high throughput screening (HTS) methods, have enabled us to improve, stabilize, integrate and alter the functions and properties of biological materials.

In protein engineering rational design involves alterations of selected residues in a protein via site-specific mutagenesis to achieve predicted changes in function. Protein engineering refers to the ability to alter protein structure to achieve a desired protein function.

DNA shuffling will play a key role in biomolecular engineering. DNA shuffling exchanges large functional domains of sequences to search for the best candidate molecule, thus mimicking and accelerating the process of sexual recombination in the evolution of life. The phage‐display system of combinatorial peptide libraries will be extensively exploited to design and create many novel proteins.
Biomolecular Engineering

Biolistics

What is biolistcis? Biolistics, short for “biological ballistics” is a method for the delivery of nucleic acid to cells by high-speed particle bombardment. The technique uses nucleic acid-coated particles propelled by a pressurized gun (gene gun) to transfect cells or organelles. It can also be used to deliver vaccines.

It is a new process which employs high velocity microprojectiles to deliver substances into cells and tissues. Biolistics also known as: Particle Bombardment; Microprojectile bombardment; Particle acceleration; Particle inflow gun; Gene gun: Bio-blaster.

Biolistics including particle bombardment is a commonly used method for genetic transformation of plants when either cells/tissues or intracellular organelles are impermeable to foreign DNA.

Millions of DNA-coated metal particles are shot at target cells or tissues using a biolistic device or gene gun. The DNA elutes off the particles that lodge inside the cells, and a portion may be stably incorporated in the host chromosomes.

The plant cell wall is usually impermeable to foreign DNA. Utilization of the gene gun method has shown better results against the various barriers that hinder the delivery of foreign DNA inside the organelle/cell/tissue.
Biolistics

Nanotoxicology

Nanotechnology grows rapidly and has potential applications in many areas such as industry, agriculture, business, medicine etc.

Nano-materials play an effective role in food preservation, packaging process and packaging material. Candies, sweets, and chewing gums have gained popularity because of the use of Nano-materials.

Uses of nano-scale materials in the food industry are likely to improve the processed food. Nano-materials are being used as coated materials in treatment and as diagnostic tools.

Nanotoxicology is defined as the study of the nature and mechanism of toxic effects of nanoscale materials/particles on living organisms and other biological systems.

In traditional toxicity, “the dose” defines “the poison”. However, this point of view should be modified in nanotoxicology.

Nanotoxicology is intended to address the toxicological activities of nanoparticles and their products to determine whether and to what extent they may pose a threat to the environment and to human health, and defined as the study of the nature and mechanism of toxic effects of nanoscale materials/particles on living organisms and other biological systems.

It is important to note that nano-materials may have toxic effects in the body due to their increased contacting levels. In addition, there may be potential and unpredictable risks to use in food packaging.

Shape, size and composition of the nanoparticles regulate the toxicity. Nanoparticles inherently possess higher surface area to volume ratio compared to bulk metals due to which they can be highly reactive and they are estimated as absorbed 15–20 times more compared to the respective bulk particles.

Nanotoxicology investigation because of the processing of nanoparticle in biological systems possibly will lead to unpredictable effects. Nanoparticle is having a capability to cross the biological membrane and access the cells tissue and organ inhalation and consumption.

Generally, nanomaterial size, shape, surface chemistry, and degree of aggregation are key factors that influence the toxicity. The size of nanomaterials influences the cellular uptake and response to nanomaterials, their distribution, and elimination from the body.

The field of nanotechnology has expanded day by day since nanomaterials are used in many applications in people daily life. Human exposure to nanomaterials is unavoidable. Nanoparticles easily enter the environment via various routes, and ultimately enter human body through direct routes such as dermal and oral exposures, nanodrugs, or through indirect routes such as the food chain, etc.

The area of food production wherein nanotechnology can have a great impact is in food packaging. Studies have indicated that consumers are more willing to accept the presence of nano-materials in packaging than in food itself. However, the nano-materials in food packaging may potentially migrate to food, which in turn can be ingested or inhaled, or even be transferred through skin contact. Studies on nanoparticles of titanium, silver and CNTs have shown that these materials could enter blood circulation, and their insolubility may cause accumulation in organs.
Nanotoxicology

Hyponatremia: definition and etiology

Hyponatremia is a common electrolyte disorder defined as a serum sodium level of less than 135 mEq per L is the most common disorder of body fluid and electrolyte balance encounte-red in clinical practice.

It is associated with increased mortality, morbidity and length of hospital stay in patients presenting with a range of conditions. Hyponatremia is therefore both common and important.

Hyponatremia results from the inability of the kidney to excrete a water load or excess water intake. Water intake depends upon thirst mechanism. Thirst is stimulated by increase in osmolality.

Thirst is sensed by osmoreceptors located in the hypothalamus and leads to the release of anti-diuretic hormone (vasopressin) from the posterior pituitary. Anti-diuretic hormone acts on the V2 receptors located at the basolateral aspect of the collecting duct cells and leads to increased aquaporin expression on the luminal aspect of the collecting duct cells which increases water absorption and abolishes thirst.

The most common causes of hyponatremia are the syndrome of inappropriate anti-diuresis (SIAD), diuretic use, polydipsia, adrenal insufficiency, hypovolemia, heart failure, and liver cirrhosis (the latter two are often collectively referred to as “hypervolemic hyponatremia”).

The most common classification system for hyponatremia is based on volume status:
*hypovolemic (decreased total body water with greater decrease in sodium level)
*euvolemic (increased total body water with normal sodium level)
*hypervolemic (increased total body water compared with sodium)

Hyponatremia: definition and etiology   

What is milk solid?

Milk is approximately 87 percent water and 13 percent solids. As it comes from the cow, the solids portion of milk contains approximately 3.7 percent fat and 9 percent solids-not-fat.

Milk fat carries the fat soluble vitamins A, D, E, and K. The solids-not-fat portion consists of protein (primarily casein and lactalbumin), carbohydrates (primarily lactose), and minerals (including calcium and phosphorus).

Solids-not-fat (SNF): proteins, lactose, minerals, acids, enzymes, vitamins. It is the total solids content minus the fat content.

Total Milk Solids: fat + SNF

The composition of milk is subject to changes due to numerous factors such as race, environmental conditions and health status of the mammary gland. Fat and protein are the components that tend to suffer greatest variations in milk even when in the same environmental conditions, and these variations are generally related to the nutrition and diet of animals.

Milk with high solids-not-fat is valuable to the consumer for its flavor and nutritional value and to the manufacturer of milk products, especially relating to cheese yield. Protein is the most important component of milk because of its nutritional value and its functional properties.
What is milk solid?

Anthocyanins

Anthocyanins are the largest group of water-soluble pigments in the plant kingdom and belong to the family of compounds known as flavonoids that are synthesized by plants as part of their secondary metabolism. Based on their chemical characteristics, flavonoids are divided into different subclasses: flavonols, flavanols, anthocyanidins, flavanones, flavones and isoflavones.

Anthocyanins are colored water-soluble pigments belonging to the phenolic group. They occur primarily as glycosides or acylglycosides of their respective aglycone anthocyanidins. These pigments, naturally present in fruits and vegetables, provide color and promote health benefits to consumers due to their antioxidant capacity.

The different anthocyanin conjugates absorb light at about 500 nm and are responsible for the red, blue and purple color of fruits and vegetables.

Among the anthocyanin pigments, cyanidin-3-glucoside is the major anthocyanin found in most of the plants. The colored anthocyanin pigments have been traditionally used as a natural food colorant. The color and stability of these pigments are influenced by pH, light, temperature, and structure.

Anthocyanins have important functions in plant physiology. They are believed to play a major role in both pollination and seed dispersal. Anthocyanins have been shown to be strong antioxidants and may exert a wide range of health benefits through antioxidant or other mechanisms. Several studies have shown that anthocyanins display a wide range of biological activities including antioxidant, anti-inflammatory, antimicrobial and anti-carcinogenic activities.
Anthocyanins

Glycoproteins and its functions

Glycoproteins occur in fungi, green plants, viruses, bacteria and in higher animal cells where they serve a variety of functions. They are presents in extra- and intracellular fluids, connective tissue and cell membranes.

Glycoproteins together with glycolipids constitute the family of glycoconjugates, a term introduced in 1972. The structural glycoproteins are protein having one or more heterosaccharides chains. The protein moiety is quantitatively the most important constituent.

Connective tissue glycoproteins, such as the collagens and proteoglycans of various animal species, are structural elements as are the cell wall glycoproteins of yeast and green plants.

The class of glycoproteins includes a large number of biologically active substances such as enzymes, hormones, and immunoglobulins as well as structured components of blood vessels and skin.

The protein in milk and egg white contain carbohydrates as do most of the serum proteins. The diverse biological functions that these macromolecules perform, include among others, enzymatic catalysis, hormonal control, immunological protection, ion transport, blood clotting, lubrication, surface protection, structural support, cell adhesion, intercellular interaction.
Glycoproteins and its functions

Cell membrane

Oxidation stability

Oil and fats are a major component of the human diet, comprising roughly one-third of human caloric intake. Sensory attributes are a key component that is heavily impacted by fats.

No matter what fat is used in which foods, one factor that impacts the quality and shelf life of the food product is the oxidative stability of the fat.

Oxidative stability can be defined as the resistance of a lipid to oxidation and to the resulting deterioration that causes rancidity. Tests to estimate oxidative stability attempt to predict the shelf life of the oil by determining the extent of oxidation produced under defined and standardized conditions.

Phenolic compounds play an important role in the nutritional characteristics and oxidation stability of virgin olive oils. They are in fact natural antioxidants and the level of phenolic compounds had been found to be correlated with the oxidative resistance of virgin olive oil.
Oxidation stability

What is tomato paste?

The fruit of an annual plant or short-lived perennial Lycopersicon esculentum of which some varieties grow to over 2.5 m high whilst others are low bushes.

Tomato paste is tomato puree that has been cooked to remove almost all moisture. Tomato paste is thus a concentrated source of flavor, color and thickening power. It is also an effective emulsion stabilizer.

It is obtained by removal of peel and seeds from tomatoes, followed by concentration of juice by evaporation under vacuum. Good quality tomato paste is a homogenous mass, with a high density, without foreign bodies with a red color, an agreeable taste and smell, close to those of fresh tomatoes.

Tomato paste lends a deeper, rounded tomato flavor and color to many slow-simmered paste sauces as well as to Italian soups and stews.

A rule of thumbs for formulating with tomato paste is as follows:
Tomato paste/water 1:1 ratio ≈ puree
Tomato paste/water 1:2 ratio ≈ sauce
Tomato paste/water 1:3 ratio ≈ juice
What is tomato paste?

What is gluten?

Gluten is a protein composite found primarily in the grains of wheat, barley and rye. Less commonly known relatives of wheat such as spelt, triticale, kamut, farro and einkorn also contain gluten.

Gluten is formed when two wheat proteins - glutenin and gliadin – form cross links when they are hydrated. Most breads, pastas, baked goods, and seasonings contain gluten. It gives elasticity to dough and will help it rise and maintain its shape.

It can be used as a thickener in soups and desserts. It has so many uses and can be described as different names or aliases.

As it is metabolized or broken down, it can give some people tremendous problems. In short, the body’s immune system can see it as a toxin and therefore launch an attack against it.

Varied and multiple symptoms are created depending on what tissues of the body are attacked. Even small amounts of exposure may produce symptoms ranging from eczema, itching, headache, upset stomach, fatigue, sneezing and congestion to name a few.
What is gluten?

Definition of Nutritional Anthropology

The early history of nutritional anthropology dates back to studies of food and social organization in industrial societies in the 1930s.

The emergence of nutritional anthropology in the 1970s has tended to replicate the ‘two cultures’ of an anthropology divided methodologically and by theories into social and biological sciences. The British anthropologist Audrey Richards in 1939 is often described as the first one who explicitly focused on food.

Nutritional anthropology has been defined as the study of food and nutrition from evolutionary, behavioral, social and cultural perspectives, and understanding the interrelationship of biological and social forces in the production of nutritional health at the individual, community and population levels.

Nutritional anthropology deals with nutrition as a process of the ways ‘in which humans utilize food to meet the requirements of biological and behavior functioning’.

Most published research in nutritional anthropology is found in journals and per-reviewed books relating to nutrition, medicine, epidemiology, and food anthropology.

Nutritional anthropology uses methods, theory, and data from anthropology, public health, medicine, nutritional science, demography, human biology, plant and animal biology, agronomy and epidemiology to examine food acquisition, processing, consumption and nutriture.
Definition of Nutritional Anthropology

What is β-carotene?

β-carotene is an organic compound and fat-soluble vitamin. Along with giving carrots, sweet potatoes and other foods their orangey color, β-carotene provides a non-toxic way for people to satisfy their need for vitamin A.

The liver converts β-carotene to vitamin A. Diets rich in carotenoids typically supply 5 mg to 10 mg of β-carotene each day. The conversion of β-carotene only as much as is needed, thus avoiding possible toxicity and therefore making β-carotene superior to preformed vitamin A.

β-carotene

β-carotene prevents the breakdown of cells and tissues that is brought on by oxidation and free radicals. This aids the immune system whole slowing the rate at which the people age.

Since β-carotene acts as an antioxidant, it serves as a protector against potential cancer causing agents. It is stored in the liver for later use. When taken with vitamins: C, D, and E, zinc, choline, selenium and the essential fatty acids, β-carotene appears to function with more effect.

Foods that are contain β-carotene include orangey foods such as carrots, sweet potatoes, cantaloupes, pumpkin, winter squash, mangoes, and apricots, as well as goji berries, spinach, kale, chard, dandelion greens and broccoli.
What is β-carotene?

Glycoprotein

Glycoproteins may be defined as biopolymers having amino acids and sugar reduces link covalently to each other. They are widely distributed in nature. Found in higher animals, plants and microorganisms, glycoproteins contain a protein chain of any of the 20 naturally occurring L- α -amino acid units.

Proteoglycans are a subclass of glycoproteins with distinctive structure. Glycoproteins differ from monosaccharides protein structures in that they contain considerably less carbohydrate.

The mucopolysaccharides however may be considered a type of glycoprotein. Formed in the Golgi apparatus in the process of glycosylation, glycoproteins are important components of plasma membranes in which they extend throughout the lipid layer.

The molecular weights of glycoprotein range from 15,000 up to million. Some glycoproteins have only one glycochain in a molecule, whereas other glycoprotein possesses many glycochains in a molecule. The carbohydrate chains of glycoproteins are short, consisting perhaps eighth to ten saccharides units.

D-galactose, N-acetyl-D-galactosamine, D-glucose,  N-acetyl-D-glucosamine, D-mannose, L-fucose, and sialic acid, comprise the bulk of the carbohydrate moiety.
Glycoprotein

What is prime pressed cocoa butter?

Prime pressed cocoa bitter is designed as the fat obtained from good quality cocoa nib commercially free form shell by means of mechanical (hydraulic) pressing. No subsequent refining other than filtration is employed.

Cocoa butter, which forms about 45%b of the bean is extracted by removing the beans from their pods and allowing them to ferment before they are dried, roasted, shelled and ground to the paste known as ‘cocoa liquor’ or ‘cocoa mass’.

The cocoa liquor is then by hydraulic, screw expelling or solvent extraction to produce cocoa butter. There is usually some oil remaining on the cocoa powder - it is impossible to take out all the fat simply by pressing.

Pressing liquor made from highest quality nibs gives the best quality cocoa butter which is designated ‘pure prime pressed’, but butter produced by expeller pressing of good quality nibs is almost equivalent. Solvent extraction is used only from extraction of cake residues from the expeller process or of other, waste, residues.

Prime pressed cocoa butter is usually used directly in chocolate without any further processing. This makes it unusual among fats in the most fats are refined before use to remove unwanted minor components such as free fatty acids, pigments, oxidation products and off-flavors.
What is prime pressed cocoa butter?

Chemical solvent extraction in food

Solvent extraction is a separation method which applies a solvent to extract/separate a desired component or the solute from solid food.

The separation factor for solvent extraction is the chemical equilibrium of the component between solid and solvent phases and the driving force of the solvent extractions the difference or gradient of chemical potential of a given species between an organic phase and an aqueous phase.

The difference in solubility relate mainly to issues of charge or polarity and the nature of the association between food and other components with the material to be extracted.

Once a solid is in contact with a solvent, the concentration difference drives a net flow of solutes from the solid phases to the solvent in an attempt to reach equilibrium. The bigger the concentration difference, will give the larger the driving force and the more efficient the extraction.

Solvent extraction used in numerous chemical industries to produce pure chemical compounds ranging from pharmaceuticals, food, and biomedical to heavy organics and metals, in analytical chemistry and in environmental waste purification.

Oleoresins are one example of the products of the extraction of spices and herbs using an organic solvent, followed by the removal of the solvent.

In United States solvent extraction with petroleum ether has been used primarily for the production of soybean oil.
Chemical solvent extraction in food