Waste and By-product Utilization 2(1+1)

Lesson 15.

Categories of organisms of public health significance

Pathogens and Parasites	Minimal Infective Doses
Salmonella spp.	10
Shigella spp.	10
Escherichia coli	10
Vibrio cholerae	10
Escherichia coli O157:H7	100
Campylobacter jejuni	about 500
Giardia lamblia	10
Cryptosporidium cysts	10
Entamoeba coli cysts	10
Ascaris	1–10 eggs
Hepatitis A virus	1–10 PFU

Most microbial contamination is on the surface of fruits and vegetables. If pathogens are not removed, inactivated, or otherwise controlled, they can spread to surrounding produce, potentially contaminating a significant proportion of the produce .Therefore washing fresh produce (also known as surface treatment) can reduce the overall potential for microbial food safety hazards. Also, Sanitizers or anti-microbial in wash water and other processing water may be useful in reducing pathogens on the surface of produce and/or reducing pathogen build-up in water.

The effectiveness of a sanitizer depends on its chemical and physical nature, treatment conditions (such as water temperature, pH, and contact time), resistance of pathogens, andthe nature of the fruit or vegetable surface. Chlorine is a commonly used anti-microbial. Chlorine dioxide, trisodium phosphate, organic acids, and ozone have also been used as anti-microbials in produce wash water. All chemical substances that contact food must be used in accordance with FDA and EPA regulations.  Food-processing wastewater can be characterized as non toxic, because it contains few hazardous and persistent compounds. With the exception of some toxic cleaning products, wastewater from food-processing facilities is organic and can be treated by conventional biological technologies.  Due to increased enforcement of discharge regulations and escalating POTW surcharges, many food-processing facilities are taking steps to either reduce, recycle(or renovate), and/or treat their wastewaters before they discharge them.

Another contaminant of food-processing wastewaters, particularly from meat-, poultry, and seafood-processing facilities, is pathogenic organisms. Wastewaters with high pathogenic levels must be disinfected prior to discharge.

Bacteriological Analysis of water

The bacteriological analysis of water is done primarily to determine the fitness of water. As many diseases are of intestinal origin e.g. typhoid fever, dysentery etc and are transmitted through contaminated water. It is very important to check the presence of coliforms in waste water as they are closely associated with the pathogenic organisms and a present in large numbers in polluted waters. On the other hand, detection of specific pathogenic organisms in water supply, because of their minute number is much more difficult.

The coliform group which derives its name from the colon or large intestine of man is inhabited by a particular genera called Escherichia coli or E. coli. this bacteria out numbers the other pathogenic microorganisms. Hence it serve as a very good indicator organisms and taste conducted to determine their presence.

Bacteriological analysis involves the following tests:-

1. Total count of Bacteria, also called standard plate count.

2. E. coli test

SPC test

The standard plate count provides an estimate of the total number of bacteria in a water sample, which will grow and develop in a particulate medium at a temp of 37°C (human body temp) for a period of 24 hrs under lab conditions.

Standard plate count through not of much use in ascertaining the sanitary quality of water, helpful in determining the bacterial efficiency of filteration units in water treatment plants.

E. coli test

It includes 3 tests

a) The  presumptive test

b) The confirmed test

c) The completed test

a) The presumptive test:  It consists of incubating water samples (diluted) along with lactose broth as a culture medium for 24-48hrs at 37°C. The sample is placed in standard fermentation tubes called Durhum tubes. The test is said to be positive if gas is evolved and negative if no gas is evolved. The negative presumptive test would indicate that the water is safe for use.

b) The confirmed test: this test is required as the production of gas in lactose broth doesnot necessarily indicate the presence of bacteria of coliform group, because there may be other bacteria present which also ferment lactose. If now, a portion of the broth from previous fermentation tubes showing gas is placed in other fermentation tubes containing brilliant lactose bile as the medium and incubation carried out as before i.e for 48hrs at 37°C. The formation of gas in these tubes would confirm the presence of the organisms of the the coliform group i.e E.coli the test is then said to be positive and water unsafe for use. The brilliant bile is used because it inhibits the growth of bacteria other than the coliform organisms.

c) The completed test: This test is not always necessary and is done sometimes to demonstrate with certainly that the organisms showing positive results for the confirmed test are really members of the coliform group. The test involves streaking of endo or eosin methylene blue plates from each brilliant green bile tube showing gas and incubating for 24 h at 37°C and then picking only discrete colonies well isolated and inoculating in lactose broth fermentation tubes and on agar slants and finally incubating for 48 h at 37°C. The formation of gas in lactose broth and the appearance of gramnegative non-spore forming bacilli are taken as a satisfactory completed test.

Water borne diseases

When water contains harmful and disease producing matter, it may lead to many disease on being consumed by healthy persons. The so called water borne diseases is caused by following factors.

a) Presence of micro organisms:  Which originates from the intestinal disorders of infected persons.

e.g. Cholera is caused by vibrio cholera

        Typhoid is caused by salmonella typhi

        Hepatitis A is caused by Hepatitis A

b) Presence of Parasitic ova: The eggs or developed embryo of round worm and tape worms are generally carried by water and causes diseases.

c) Presence of inorganic matter: Certain diseases may result from the presence or absence of certain minerals in waters. Some minerals may be toxic by their more presence while others become toxic when their quantity exceeds a certain limit eg lead, arsenic, fluorides, sulphates of magnesium, Iodine etc.

d) Presence of organic matter: An excess of organic matter in the water may lead to diarrhea and other gastric disturbances in the human body. The complete control of water borne diseases involves instituting an environmental health programme that incorporates personal and household hygiens control of fly species and other insects monitoring of food processing, immunization of population where possible and proper scientific waste disposal and water treatment to remove harmful constituents.

Insecticide, pesticides and fungicides residues

Additives are used in the food processing industry to facilitate plant operations and provide sanitation.  These chemicals often pass through the plant and may interfere with the disposal of process waste.  In addition, chemicals are used to preserve food, control moisture, control texture, enhance flavour, decrease cooking/preparation time and enhance nutritional value.  The vast majority of these chemicals remain in the product and are not found in the waste streams in significant concentrations. Four categories of chemicals that are of importance to wastewater treatment and disposal are commonly used at food processing plants to facilitate operations.

• Ligands

• Pesticides

• Sanitizers

• Surfactants

Ligands

Ligands are also called complexing or sequestering agents.  Their primary use is to reduce scaling.  Scaling can build up rapidly and leads to clogged pipes, inefficient heat exchange and uneven temperatures.   Scale that flakes off can enter machinery and cause premature wear .A ligand is an ion with a bonding site that can donate an electron pair in order to form a bond with a metal ion.  Chelating agents are ligands with two or more bonding sites. Ligands are sorted into three categories, organic acids, phosphates and phosphonates.  Organic acids are the strongest.

• Organic Acids

-  Aminopolycarboxylic acids (ACPAs)

-  Ethylenediaminetetraacetate (EDTA)

-  Nitrilotriacetate (NTA) 

-  Diethylene-triaminepentaacetate (DTPA)

-  Hydroxyethylenediaminetriacetate (HEDTA)

-  Hydroxycarboxylic acids - Citric acid

• Phosphates - Sodium polyphosphates

• Phosphonates - Organophosphonates

Pesticides

Pesticides reduce pests in the food processing plant such as rodents, insects and fungi.

Large quantities may be used in facilities that handle fresh produce.  Additionally, residual pesticides on the commodity may enter the waste stream during washing. Pesticides are sorted into three categories, insecticides, herbicides and fungicides. Categories are further divided up into classes of chemicals with common examples listed, with the exception of fungicides which are not widely used food processing industry

Insecticides

Carbamates(Aldicarb,Carbaryl,Carbofuran)ƒ

Organochlorines(Methoxychlor,Endosulfan,Lindane)ƒ

Organophosphates (Chlorpyrifos,Diazinon,Malathion)ƒ 

Pyrethroids(Cypermethrin,Cyfluthrin, Esfenvalerate)

Herbicides

Benzoic acids, Paraquat, Phenoxy acids, Substituted ureas, Triazines

Sanitizers

Sanitizers are used to deactivate bacteria on food contact surfaces.  The more concentrated the sanitizer is, the more damaging it is to microbial populations.The mechanisms vary but are generally the physical destruction of the cells and/or inactivation of cell function at the genetic level. Sanitizers can be divided into two categories, oxidizing agents and non-oxidizers.  Oxidizing sanitizers may be further categorized as either halogen or peroxygen. Organic bromine compounds work synergistically with many chlorine compounds. Non-oxidizing sanitizers include acid sanitizers, acid anionic sanitizers, acid-quat sanitizers and quaternary ammonium compounds.

Surfactants

Surfactants lower the surface tension of a solvent, such as water.  This allows other cleaning compounds to penetrate a water film surrounding a dirt particle so that bonds can be formed. There are four types of surfactants: anionic, cationic, non-ionic and amphoteric.  Anionic surfactants account for 50% of surfactant use in Europe and 60% in the United States. The balance, roughly 40%, is non-ionic surfactants. 

Anionic surfactants

Alkyl sulfates

Ether carboxylates

Ether sulfates

Isethionate esters

n-Acylated amino acids

Phosphate esters

Sulfonates

Sulfosuccinate esters

Nonionic surfactants

Alkyl polyglycosides

Amine oxides

Esters of polyhydroxy compounds

Ethoxylated compounds

Fatty acid alkanolamide