Use of Total Aerobic Count as a Means for Determining Food Microbial Specification

Total aerobic count is one of the two most often used microbiological tests for foods. It is mainly appropriate for:
1. Testing process integrity.
2. Determining general sanitation levels of foods and food processing environments.
3. Determining probability of previous temperature abuse of food and raw materials.
4. Determining incipient of food spoilage.

To determine levels of acceptable aerobic microbial count, the following should be taken into consideration:
1. The type of food and type of microbial flora natural to the food product or raw material.
2. Microbial level should be balanced by what is achievable by the food process and processing conditions.
3. The level should be within the industry norms.
4. The Industry's economical status should be considered.
5. Level should be based on past experience, literature, and available data for the food product category.

Proliferation of Yeasts and Molds in Low Moisture Foods

In foods of low water activity, yeasts and molds proliferate by changing their internal cell moisture concentration form high to low water activity. To do this, they synthesize some water binding molecules (solutes) which can be used at their discretion to trap water from the surrounding environment. The trapped water is then used for biochemical reactions required for growth. E.g. of these solutes include glycerol, glucose, sucrose and sorbitol.
The presence of these compounds also decreases the water activity of the fungi cells, thereby buffering them and enabling equilibrium between the cells and the environment. Increase in solute concentration and decrease in water activity of the cells allow the movement of water from the environment into the cell, thereby enabling growth and proliferation of the yeast and mold.

Chocolate Bloom

Chocolate bloom is the situation whereby fat crystals that were formed initially upon cooling a piece of chocolate, melts, migrates to the surface of the chocolate, and recrystallizes into a more stable form. This gives rise to an unstable appearance that is characterized by a dull color and grayish spots on the chocolate.
Chocolate bloom can be prevented by tempering of the cocoa fat before chocolate manufacture, and by hydrogenation of the emulsifier (usually lecithin) to a more stable form before use in the manufacture of chocolate.
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Natural Pigments in Foods

Chromaphoric compounds are substance that contain chroma. There are functional groups called chromaphores which when added to a saturated hydrocarbon, causes absorption in the UV or visible range, to produce colors. Saturated hydrocarbons are colorless, but when a chromaphore is added to it, a color compound is produced.
E.g. of simple chromaphores include the following:

1. Carbonyl Group
This is a carbon atom bonded to an oxygen atom like in Aldehydes and Ketones.

2. Azo Group
This is a Nitrogen atom bonded to another Nitrogen atom. It absorbs light in the visible UV region. Most synthetic food colors are in the form of azo-dyes. E.g. of an compound with an azo group is Azo Benzene.

3. Nitrate Group
This is a Nitrogen atom bonded between two Oxygen atoms. This chromaphore also absorbs light in the visible UV region.

4. Ethylene Group
This isolated chromaphoric group absorbs light at a wavelength of 190nm. It consists of two double-bonded carbon atoms. The amount of light absorbed by this chromaphoric group as part of a complex compound varies, depending on its molar absorptivity. When a compound contains conjugated ethylene groups, the wavelength for light absorption increases.

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Flavor Development in Plants and Animal Tissues

All flavor components in plants and animal tissues are as a result of cellular metabolism. Since cell structures in plants and animals are different, there exist some similarities and differences of flavor development in these tissues to a certain degree.
A striking similarity is in the production of metabolites by enzymic reactions. Plants and animal tissues undergo physiological reactions at the cellular level which is manifested in food metabolic pathways. The substrates and products of these pathways are compounds that may contribute to the flavor of the tissues. E.g. The production of acetaldehyde in grapes, acyl-amyl acetate in bananas, lactic acid production in meat muscles.
Furthermore, the disruption of cell structure in plant tissues has a profound effect on flavor development that is similar to the effect of membrane disintegration in animal tissues. When cell wall membranes of biological tissues are disrupted, cellular components are released which contribute to the flavor of the tissues. Also during cell disintegration (grinding, milling, macerating, chewing), various compounds which were formerly contained within separate compartments in the cell are liberated. These compounds react with each other and with compounds in the external environment like oxygen, water, saliva, and enzymes, to form a lot of new compounds contributing to the flavor of the food. E.g. The reaction of amylase in saliva with starchy components in tissues during chewing to form sugars which contribute to the sweet taste of cereals and grains.
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Advantages and Disadvantages of Different Extraction Techniques for Isolating Flavor Compounds from Foods

1. Dynamic Headspace Extraction
Advantages: Rapid analysis, sensitivity, minimal equipment investment, ability to analyze sample with traditional GC.
Disadvantages: Sample must be in liquid state, inherent analytical limitation to compounds that do not co-elute with solvent, contamination by culture medium, presence of solvent impurity peaks.

2. Static Headspace Extraction
Advantages: Minimal sample preparation, simplicity, rapidity, use of little or no solvent, inexpensive.
Disadvantages: Restricted to analysis of volatiles and concentrated compounds that elicit strong detector response, does not detect poorly volatile compounds.

3. Solid Phase Extraction
Advantages: Cleaner extract, easier to automate, higher recoveries for polar compounds.
Disadvantages: Incomplete removal of interferences, low recovery of analytes, high variability in results.

4. Solid Phase Micro-extraction
Advantages: Simple, time saving, high screening, high throughput, eliminates environmental hazards.
Disadvantages: High selectivity of SPME fibers towards chemicals, lack of robustness, low reproducibility of results due to ageing of fiber, presents problems in quantitative measurements.

5. Steam Distillation
Advantages: Low cost, simple.
Disadvantages: Time consuming, high temperatures used may alter compounds.

6. Supercritical Fluid Extraction
Advantages: Good quality extract, efficient, selective, minimized product degradation, eliminates solvent residues.
Disadvantages: High cost, technical skills required.

7. Direct Solvent Extraction
Advantages: Simple, no complex equipment, controlled recovery, large selectivity and flexibility.
Disadvantages: Emulsion formation, not efficient, loss of compounds, complicated, laborious, pre-concentration step required.

8. High Vacuum Distillation
Advantages: Low-cost, high throughput, reduces thermal hazard, efficient, purity of distillate.
Disadvantages: Time-consuming, requires technical skill.

9. Dialysis
Advantage: High purification.
Disadvantages: High cost, technical skill required, time-consuming, large samples needed, loss of raw materials, concentration of dialysates required.

Bacterial Spores and Food Safety

Bacterial spores when present in processed foods can germinate under favorable conditions and cause either food spoilage or food borne illnesses when the food is consumed. E.g. the spores of Clostridium botulinum present in low acid canned foods. The use of high temperature processing in combination with anaerobic storage conditions is usually sufficient to eliminate bacterial spores based on their D-values. However, if marginal heating is done (sub-lethal heat processing) due to compromises for nutritional or organoleptic quality, the spores may survive and subsequently germinate, causing a food safety problem. Although GMP of thermally processed foods requires that enough heating be applied to eliminate microbial vegetative organisms and spores, sometimes residual bacterial spores, especially the spores of thermophillic organisms may still be present following the heating process of canned foods. However these thermophillic spores may pose no food safety problem due to the fact that the cans are cooled down quickly following the heating process and then stored at room temperature conditions, which inhibit the germination, and subsequent proliferation of the spores. In dried/powdered foods that are to be reconstituted before consumption, bacterial spores, if present, can become a food safety problem and can lead to spoilage of the improperly stored reconstituted food or lead to intoxication of consumers when the food is ingested.
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Trends in Carbohydrate Consumption in the U.S

The trends in carbohydrate consumption in the U.S. had been increasing for almost a decade since 1990. This increase is especially noticed for carbohydrate consumption in form of caloric sweeteners, and refined carbohydrate products. Caloric sweetener consumption as used in sweetening drinks like tea, fruit juice, or sodas; or as used in products like candies, baked goods, and fried flour-based products tremendously increased (almost doubled) between 2000 to 2003. The consumption of refined carbohydrate products like bread, pasta, and breakfast cereals in the U.S. also increased from 1993 to 2003. This increase may have resulted from the fortification of bread and cereals with vitamins and minerals, which caused a lot of consumers, especially women of child-bearing age, to increase their intake of these fortified high carbohydrate foods.

Furthermore, the advice by the USDA within that period for consumers to decrease their total lipid intake, led to a colloquial idea that carbohydrate intake could be increased without causing much harm. The consumers believed that "if fats are bad, then carbs are good". The information sent out by the USDA food pyramid of 1990 only helped to make matters worse. This pyramid featured high carbohydrate foods at its base and encouraged the average consumer to consume at least 5-6 servings of carbohydrate rich foods. Food industries and manufacturers were not left out of the "fat is bad" hit. Efforts were made to compensate for deceasing fat content in processed foods, by increasing their total sugar content. This was done in a bid to maintain good taste and functional properties as well as consumer appeal in food products.

In recent times (within the last few years) however, the use of calorie reduced sweeteners in food product formulation has been received as a saving grace to the "too much sugar situation". Many food manufacturers, formulators and consumers have embraced these non-caloric and reduced-caloric sweeteners as the means to reducing the high sugar content of most sweet foods. Furthermore recent focus on the use of whole cereal and grains in food product development, and the addition of soluble and insoluble fibers to carbohydrate rich foods, are geared towards improving the nutritional content of foods formerly developed with refined carbohydrate ingredients, thereby making them more healthy for consumption.
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Goat Milk for Infant Formula Development

The ideal food for infants is human milk. However, due to certain reasons, some infants do not have access to breast milk. As a greater understanding of the nutritional requirements of infants developed, various alternative infant feeding preparations were manufactured from the late 19th century. However, until the 20th century, there was virtually no safe and reliable alternative to breastfeeding. Most present-day infant formulas in the US market are adaptations of the product designed by H.J. Gerstenberger and co-workers in 1915.
Goat milk modification for infant feeding is still a very new area and has not been achieved in most parts of the world due to the relative differences between goat's milk and cow's milk, as well as differences between these to human milk.
Literature has shown that goat milk adapted for infant feeding might be a suitable substitution for cow milk formulas due to the higher tolerance of goat milk by infants who are allergic to cow milk proteins. The higher protein and non-protein nitrogen and phosphate in goat milk produce a greater buffering capacity than cow milk. Furthermore, many infants allergenic reactions to cow milk, stem from the excess mucus production of this milk, unlike in goat milk.
Some physico-chemical properties of goat milk such as smaller fat globules, higher percentage of short and medium chain fatty acids, and softer curd formation of its proteins are advantageous for higher digestibility and healthy lipid metabolism.
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Food Process Mechanisms Leading to Loss in Protein Quality

During the course of food product development, many formulators often experience loss in protein quality and bioavailability due to processing techniques and other parameters. Below are some of the mechanisms that lead to protein quality loss during food formulation. You are invited to post your comments!

Heat Destruction:
This is the destruction of amino acids contained in proteins by use of very high temperatures, leading to loss in functionality of the protein.

Non-Enzymatic Losses:
This is a loss in protein quality not requiring the action of enzymes. E.g. Maillard browning (formation of brown coloration in foods as a results of amine group of amino acids reacting with the aldose, ketose group of chemical compounds and/or reducing sugars, to give rise to complex products, which results in protein loss).

Protein-Protein Crosslinkage:
This is the formation of new linkages, or the modification of existing linkages between the amino acids of proteins, thereby causing a loss in bioavailability of these amino acids.

Protein Isomerization:
This is the formation of a protein isomer as a result of the processing conditions under which the food was subjected - leading to loss in bioavailability of amino acids in the protein. E.g. conversion of an L-Amino acid to the D-isomer.

Protein Oxidation:
This is the destruction of proteins by autolysis of fatty acids and fat compounds that are either in interaction with the protein or in close proximity to the protein, thereby leading to oxidation of the amino acid contained in the protein.

Alkali Treatment of Proteins:
The use of alkali in food treatment may lead to a loss in protein function, quality and bioavailability. E.g. Formation of hard curd from milk by alkali treatment which results in protein non-digestibility.

Losses by non-reducing mechanisms:
E.g. Caramelization (this is the formation of brown pigments on food surfaces when the amino group of certain amino acids reacts with carbonyl compounds under the influence of high temperatures, leading to losses in protein function and quality.

Food Plant Sanitation: Chlorine-Based Sanitizers

These are the most commonly used sanitizers in food plants. They include sodium hypochlorite, calcium hypochlorite, chloramines, chlorine dioxide, and chlorine gas. When added to water, these sanitizers form hypochlorous acids (HOCl), which is the most effective antimicrobial form of chlorine. In this form, it is colorless, relatively non-toxic, and nonstaining.
It acts on microbial membranes, inhibits cellular enzymes involved in glucose metabolism, has a lethal effect on DNA, and oxidizes cellular proteins. The available chlorine (amount of HOCl present) is a function of pH. Optimum pH range is 6.0 to 7.5. Deadly chlorine gas is formed at pH less than 4.0. Presence of solids, fats, proteins, and other organic compounds will inactivate chlorine as an antimicrobial.
One good use of chlorine-based sanitizers is in the poultry manufacturing plants. USDA requires poultry to be immersed in water containing 20 ppm available chlorine. This action greatly reduces the amount of incidence microorganisms on the raw meat.
There are other food plant sanitizers that are currently being used in food manufacturing plants. You are invited to post your comments!

Trans-fat Reduction in Formulated Food Products

With the mandate by FDA for labeling trans-fat content in foods, food manufacturers are seeking alternatives to the traditional hydrogenation process. Fortunately, the reduction or elimination of trans-fat in formulated food products can be achieved on several levels of the food manufacturing cycle in several ways that may involve both the ingredient supplier and food formulator.
A simple way to achieving this goal is the substitution of ingredients containing trans-fat for fat-free ingredients. For example, since trans-fat can be produced naturally in milk, it would help to substitute vegetable oil for milk fat whenever possible, without compromising product taste and functionality.
Another means of reducing trans-fat levels involves the oil ingredient. High temperature treatment used to deodorize RBD oils is a cause of trans-fat production in oil ingredients used for manufacturing products like margarine, and spreads. Food formulators can avoid the introduction of trans-fat into food products by using oils that do not need to be deodorized (e.g. olive oil) in their product formulations.
A more recent means that has been employed with great success by most formulators is the use of crystallization or fractional crystallization techniques on liquid oils to produce plastic or hard fats, thereby eliminating the need for the hydrogenation process, which is mostly responsible for the formation of trans-fat in food products.
Finally, a very innovative way that has been employed to develop trans-fat free margarines and spreads with remarkable success involve replacing the hydrogenation process with interesterification processes. A better approach to this process is the use of enzymatic catalysis rather than chemical catalysis. There are several advantages of enzymatic catalysis over chemical catalysis for transesterification processes.
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Resistant Starch

Resistant starch has been defined as the fraction of dietary starch that is non-digestible by the body. Modification of native starches with chemical, physical, and enzymatic methods may lead to the formation of indigestible residues. The incomplete digestion and absorption of starch in the body gives rise to the phenomenon of resistant starches, which have physiological functions identical to that of dietary fiber. Characteristics of resistant starches include small particle size, white appearance, bland flavor, customized water holding capacity and gelatinization temperature, good extrusion and film forming properties, and cold water solubility. Resistant starches can also be used to improve appearance, texture, and mouthfeel of baked food products and to formulate low-bulk high-fiber products.
Resistant starch ingredients are making more appearances in white cereal products like bread and pasta.
There are some processing advantages and disadvantages associated with the use of resistant starch during product formulation as well as some benefits of resistant starch to the product manufacturer and consumer alike.
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Effect of Thermal Modification and Lipid Oxidation on Traditional Food Flavors

Thermal modification of foods involves heating foods to optimum temperatures so as to achieve desirable changes in the quality and flavor of the food. Thermal modification contributes to the flavor of traditional foods by inducing both desirable and undesirable flavors in the food which are responsible for the distinctive character of the food. The action of heat (cooking, frying, steaming, roasting, grilling, etc) contribute to the characteristic flavor of traditional foods by release of volatiles, induction of maillard reaction, condensation, polymerization, and degradation of organic and chemical compounds. The degree and manner to which foods are thermally modified determine the type of flavors produced, which also characterizes the distinctive flavor attributes of the food.
Lipid oxidation is the addition of oxygen molecules unto unsaturated fatty acids leading to the formation of peroxides, which are then degraded to form secondary oxidation products e.g. aldehydes, ketones, and hydrocarbons. Lipid oxidation can also contribute some desirable flavor attributes that are characteristic of processed foods.

Energy Drink Formulation

There is a recent surge in the number of energy drinks available on the shelf today. Many beverage manufacturers are beginning to realize the importance of whey proteins in drinks formulated to provide quick and prolonged energy. Another area of interest is the use of non-caloric sweeteners and exotic flavors in these beverage formulations. Although these beverages provide the required long-lasting energy, they are also empty in nutritional nourishment. Is the trend of non-nourishing energy drinks here to stay or do we foresee future reformulations of these beverages to enhance their nutritional value?
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