Metal Detection Best Practices

Metal poses a potential risk in a variety of food products, but this threat can be significantly mitigated by employing suitable equipment and implementing an effective program to manage stray metal particles.

While conscientious food producers have long recognized the importance of controlling metal contamination in food, the adoption of quality control inspections has now reached unprecedented levels. The growing awareness of potential physical metal hazards in food products has spurred an increased demand for more advanced detection strategies, a demand reinforced by regulatory agencies.

Metal contamination typically arises from four sources: raw materials (such as metal tags or screen wire in powder), personal effects (like paper clips or jewelry), maintenance activities (including welding swarf or shavings), and in-plant processing (resulting from small parts or shavings from mills, blenders, slicers, etc.).

A metal detection loop comprises three crucial components: product transfer, the metal detection system, and the reject system. Modern metal detection systems must meet the minimum requirement of rejecting contaminated products from the production line while accurately confirming the rejection. Achieving this relies on precise timing and speed control mechanisms, particularly on high-speed production lines.

To maximize the effectiveness of metal detection, the detector should be positioned as close as possible to the finished product fill station, or all sealed packages should pass through a detector. The integration of inverter controls into the main power supply of the metal detector ensures diligence, enabling the detector to automatically determine reject timing, even when adjusting line speeds remotely or manually.

However, relying solely on a metal detector is insufficient to ensure the detection and removal of all metal. For optimal results, the metal detector should be part of a product-specific quality assurance program. This program requires constant calibrated checks by qualified quality control staff, including regular sensitivity tests scheduled by the metal detector.

The fundamental principle of metal detection revolves around the transmission and reception of electrical impulses, similar to radio waves. All metals possess characteristics that alter the transmitted signal due to their conductivity and magnetic properties.

Quality assurance involves sensitivity checks using samples of various magnetic, non-magnetic, and stainless metals. The testing program undergoes verification, with the metal detector confirming that the test samples match the correct metal type, dimensions, and electromagnetic conductivity required for the specific product under inspection.
Metal Detection Best Practices

Microbial contamination in milk

The milk market requires and offers safe and high-quality products, preventing  a contamination source by good hygiene practices to reduce a possible exposure of  food-borne pathogens and chemical milk residues.

Dairy products can harbor a variety of organisms, including many zoonotic bacteria such as Brucella abortus, B. melitensis, Campylobacter jejuni, Escherchia coli, Listeria monocytogense, Mycobacterium bovis, M .tuberculosis, Salmonella, Staphylococcus aureus, and Yersinia enterocolitica ,which can cause serious disease, especially in children, pregnant women, elderly, and compromised individuals.

Many of the microbiological hazards associated with dairy products such as butter, cheese, and yoghurt are derived from the raw milk.

Generally, pathogenic microorganisms can contaminate raw milk in two ways. First, endogenous contamination occurs when milk is contaminated by a direct transfer of pathogens from the blood (systemic infection) of an infected animal into the milk, or via an infection in the udder. The second means by which fresh milk can be contaminated, known as exogenous contamination, occurs where milk is contaminated during or after collection by animal feces, the exterior of the udder and teats, the skin, and other environmental sources.

The initial microflora of raw milk reflects directly microbial contamination during production. The microflora in milk when it leaves the farm is determined by the temperature to which it has been cooled and the temperature at which it has been stored.

The infectious bovine mastitis in milk production is considered a disease with high economic impact reducing milk yield and the industrial dairy process and food safety. S. aureus and Streptococcus agalactiae are the most prevalent contagious pathogens in bovine mastitis from dairy herds around the world.

The bovine mastitis in dairy herds affects milk composition and somatic cells counts, serum protein, and proteolytic enzymes. Other undesirable milk mastitis conditions are bacterial toxins and abnormal proteins derived from inflammatory tissular response, which influence milk flavor and taste as well as milk product stability in the dairy process.

Pathogen like Staphylococcus aureus may be part of the resident microflora of the living animal, where as other pathogens such as Escherichia coli 0157:H7 or Salmonella spp. may originate from faecal contamination during initial milk collection. It can also be subjected to contamination during transport, storage and manufacturing processes.

A major cause of failure of processing and packaging systems is the development of biofilms on equipment surfaces. These communities of microorganisms develop when nutrients and water remain on surfaces between times of cleaning and reuse. Bacteria in biofilms are more resistant to chemical sanitizers than are the same bacteria in suspension.

In butter-making, bacterial contamination can come from unclean surfaces, the butter maker and wash water. Packaging materials, cups and leaves are also sources of contaminants. When butter is made on a larger processing scale, bacterial contamination can come from holding-tank surfaces, the churn and butter-handling equipment.
Microbial contamination in milk

Source of bacteria in milk

Milk is none of the most valuable foods for humans and young mammals. It also provides an excellent medium for the growth of bacteria which may spoil the milk or render in unsafe for human consumption or unfit for further processing.

Some bacteria are normally present in the udder of the cow, and these may contribute to the bacterial flora of the milk. However, unless the udder is infected, it is not considered to be an important source of such microorganisms.

In addition of udder, the exterior of the udder, the bedding on which the cow lies, food eaten by the cow, the milker (hands, nose and throat), the air in milking barn, water used to wash the udder, and milking and storage equipment are considered to be the source of bacteria.

In the handling of milk upon delivery to the processing plant or dairy, further sources of contamination may be encountered.

The hairs of the cow are always covered with dirt and dust and it is impossible for the milker to avoid a considerable amount do this dirt falling into his milk pail. Every one of these hairs which finds its way into the milk will furnish large quantities of bacteria for contamination.

Cows suffering from disease like salmonellosis, tuberculosis, and brucellosis may shed the bacteria that cause these diseases onto their milk.

In order to limit the number of bacteria present in raw milk, certain precautionary procedures are ordinarily applied. The flanks, udder, and teats of the cow should be washed, treated with a sanitizing solution, and dried before milk is drawn. Large dairy farms often have a special wash pen for cows to be milk.

It is essential to cool the fresh milk as quickly as possible. The temperature to which milk can be cooled on the farm will depend on the facilities available.

If mechanical refrigeration is available then the milk can be cooled to 3 - 5 °F and the frequency of delivery to the processing plant need no more than three times a week.

Utensils, including the milking machine, should be cleansed and disinfected either with live steam or with a solution of chlorine (about 200 ppm of available chlorine). Bulk milk tanks may be cleaned manually with detergent and water at about 54.5 °C, the sanitized with chlorine solution, or cleaned mechanically with detergent and water at 65.5° C, and finally sanitized with chlorine solution.

Outlet valves and the outside of the tanks must be cleaned and sanitized manually. Cleaning in place (CIP) may be used to clean, sanitized, and rinse the pipe line and the bulk milk line tank of a vacuum or pressure system is available.
Source of bacteria in milk

Bacterial contamination of food

Most of the bacteria are transmitted via food and water as a result of contamination with feces.

The main bacteria that cause food infections via colonization in the intestinal via colonization in the intestinal tract are Salmonella, Listeria monocytogenes, Yersinia enterocolitica and Shigella.

None of the bacteria can multiply in food or water or indeed outside the body of the host in which they developed. If they occur in food or water, one hopes that they will be inactivated or killed before they can infect a consumer or the vehicle.

There are a number of reasons and sources which result in the prevalence of bacterial contamination in food products, such as:
*Premises which are difficult to clean
*Lack of staff discipline
*Incorrect staff and product flow
*Poor air quality
*Incorrect direction of air movement

Food that is cooked and then not contaminated before being served is unlikely to serve as a vehicle for most of the bacteria.

Salmonella is the second most common cause of illness traced to contaminated foods and water. Foods most susceptible to Salmonella contamination are meat, fish, poultry, eggs and dairy products.

Much of the bacterial contamination of foods in restaurants, commissary kitchens and commercial processors are due to the poor personal hygiene of workers. Failure to wash hands after using the bathroom, sneezing and coughing into food, and picking noses and skin blemishes can all transmit pathogenic bacteria to food.
Bacterial contamination of food

Salmonella contamination in chocolate

Salmonella analysis of the final product is of great importance, owing to the nature of the harvest and subsequent fermentation in the country of origin and conditions in the supply chain, the presence of Salmonella cannot be excluded.

Salmonella does not grow in chocolate. The low moisture, high fat content, and presence of anthocyanins make chocolate an inhospitable environment for the pathogen. Temperature of 70-80 °C reached during milling, refining or conching and even after overheating at >100 °C were not sufficient to destroy small numbers of Salmonella.

Once introduced into the chocolate manufacturing process, contamination will be almost impossible to remove without closure of the factory and full cleaning, so the emphasis for control must be focused on eliminating Salmonella in the raw beans and subsequently preventing any cross contamination.

Salmonella infections flowing consumption of contaminated chocolate, although rare, were identified as early as the 1960s.

Salmonella contaminated chocolate has been fingered as the cause of several outbreaks of food-borne illness.

All Salmonella epidemics related to chocolate contamination were widely distributed temporally and geographically and affected large numbers of people , predominantly children.

More than 170 cases of infection with Salmonella eastbourne were reported in Canada and the USA in 1973 – 1974 after the consumption of chocolate products.

In 1982 imported Italian chocolate containing Salmonella Napoli gave rise to many cases of disease in England and Wales.

Salmonella contamination in chocolate

Foods associated with foodborne illness

A foodborne is considered to be any illness associated with or in which the causative agent is obtained by the ingestion of food.

Food poisoning is considered to be an illness caused by the consumption of food containing microbial toxins or chemicals poisons.

In recent years, the variety of foods associated with foodborne illness has increased.

While the food supply in the United States is one of the safest in the world, the CDC estimated that 76 million people get sock, more than 300,000 are hospitalized and 5,000 Americans die each year from foodborne illnesses.

Raw foods of animal origin are the most likely to be contaminated; there are, raw meat and poultry, raw eggs, unpasteurized milk, and raw shellfish. Because filter-feeding shellfish strain microbes from the sea over many months, they are particularly likely to be contaminated if there are any pathogens in the seawater.

Animal products such as meat, poultry, seafood, dairy products and eggs are the foods most likely to cause outbreaks of human illness in the United States.

A single hamburger may contain meat from hundreds of animals. A single restaurant omelet may contain eggs from hundreds of chickens. A glass of raw milk may contain milk from hundreds of cows. A broiler chicken carcass can be exposed to the drippings and juices of many thousands of other birds that went through the same cold water tank after slaughter.

It was estimated that meat and poultry related foodborne illness accounted for 27% of total food related cases and outbreaks between 1990 and 2003.

Fruits and vegetables consumed raw are a particular concern. Washing can decrease but not eliminate contamination, so the consumers can do little to protect themselves.

Fresh manure used to fertilize vegetables can also contaminate them. Alfalfa sprouts and other raw sprouts pose a particular challenge, as the conditions under which they are sprouted are ideal for growing microbes as well as sprouts, and because they are eaten without further cooking.

Epidemiological studies found that there are many kinds of potential error during food production, distribution or preparation that allows microbial pathogens to contaminate food. This includes:
*The use of contaminated raw food
*Cross contamination of prepared food by contaminated raw food
*Poor personal hygiene by infected food handlers
*Inadequate cleaning of equipment
*Inadequate cooling or reheating
*Improper holding temperatures
*Cooling food too slowly after heating
*Eating food too long after preparation

To provide protection against foodborne illness, it is necessary to have up-to-date knowledge of production, harvesting and storage techniques to accurately evaluate the quality and safety of raw material.
Foods associated with foodborne illness

Food Safety: Acrylamide

Acrylamide is a small and simple molecule. Acrylamide is a chemical that forms in certain foods, particularly plant based foods that are rich in carbohydrates and low in proteins, during processing or cooking at high temperatures.

Acrylamide also known as 2-propenamide and its analogue have been widely used since the last century for various chemical and environmentally applications.

In 1997, researchers at Stockholm University in Sweden were testing tunnel workers exposed to large quantities of acrylamide from a water sealant. Further tests concluded that the source of the substance came from the workers’ diets.

In April 2002 the Swedish National Food Administration reported concentration of acrylamide in a variety of fried and baked foods.

In addition to causing damage to the nervous system in human and animals and may affect reproductive processes.

The major mechanistic pathway for the formation of acrylamide in foods so far established is via the Millard reaction. Studies show that the amino acid asparagine is mainly responsible for acrylamide formation in cooked foods after condensation with reducing sugars or a carbonyl source.

Swedish scientists discovered that it acrylamide forms in fries, potato chips and other high carbohydrate foods cooked at high temperatures. However it is not found in raw or boiled potatoes.

The assessment of the risk remains hampered by lack of knowledge about the underlying toxicology, epidemiology and how people are exposed to acrylamide in food.

Acrylamide is believed to human carcinogen and severe neurotoxin. Studies have shown that acrylamide causes cancer in animals. Because very high levels of acrylamide cause cancer in laboratory animals, there is concern that dietary acrylamide may be harmful to humans as well.

The risks presented by acrylamide in food may therefore be overestimated. Nevertheless, acrylamide is considered to be a genotoxic (DNA-damaging) carcinogen, and a precautionary approach must be taken, including the assumption that there is no safe level for acrylamide in food.
Food Safety: Acrylamide