Unit 1　Food Materials Safety Control

1.1　Food Safety Hazard

A foodborne hazard is a biological，chemical，or physical agent in，or condition of food with the potential to cause an adverse health effect.

1.1.1　Biological Hazards

Biological hazards include pathogenic bacteria，fungi，viruses，prions，protozoans and helminthic parasites.There are two types of foodborne disease from microbial pathogens：infections and intoxications.Infections result from ingestion of live pathogenic organisms that multiply within the body and produce disease.Intoxications occur when toxins produced by pathogens are consumed.Intoxications can occur even if no viable microorganisms are ingested.This often occurs when foods are stored under conditions that allow the pathogens to grow and produce toxin.Subsequent processing of the food may destroy the microorganisms but not the toxin.Manifestations of biological hazards typically involve foodborne illnesses with symptoms including gastrointestinal distress，diarrhoea，vomiting and sometimes death.The U.S.Public Health Service classifies moist，high-protein，and low-acid foods as potentially hazardous.High-protein foods consist，in whole or in part，of milk or milk products，shell eggs，meats，poultry，fish，shellfish，edible crustacea（shrimp，lobster，crab）. Baked or boiled potatoes，tofu and other soy protein foods，plant foods that have been heattreated，and raw seed sprouts（such as alfalfa or bean sprouts）also pose a hazard.These foods can support rapid growth of infectious or disease-causing microorganisms.

1.1.2　Chemical Hazards

A very wide variety of chemical hazards may appear in food products either by natural occurrence in a raw material or by deliberate or unintentional addition during processing. When ingested，these may cause gastrointestinal distress，organ damage and immunological reactions that may result in death.The long-term ingestion of foods containing toxic chemicals can lead to chronic effects，including cancer.Some chemical hazards are presented below，

Naturally occuring chemical hazards：allergens，mycotoxins

Agricultural chemicals：pesticides，fertilizers，antibiotics

Heavy metals：lead，cadmium，mercury，arsenic，uranium

Chemicals used in food processing environments：lubricants，detergents，sanitizers，re frigerants，pesticides

Chemicals used in food packaging materials：plasticizers，other additives used in manu-facture

1.1.3　Physical Hazards

Food borne physical hazards are commonly called“foreign materials”or“foreign bodies”.The general sources of contamination are the environment，the food itself，the food processing facilities and personal objects.Their presence in food may result in choking，or oralor internal cuts，but rarely result in death.

Soil and stones are typical environmental contaminants during harvesting.Some foreigh material contamination originates with the food itself such as fruit stones and stems，bones or bone chips from fish and meat.A great deal of foreigh material contamination originates in food processing facilities.Nails，cut wires and broken utility blades can be dropped into the food stream by maintenance workers.Pieces of glass，hard plastic and wood splinters can enter the food from other fixtures and utensils in the processing area.Personal objects used or worn by maintenance and line workers and by food handlers in food service operations often fall into the food.These may include rings，pencils，papers，earrings，nose rings，buttons，thermometers，hair and gloves.

1.2　Control of Microbiological Hazards

Some educators refer to the“three Ks”as a comprehensive programme of microbiological hazard control in food production，those being，“kill them”，“keep them from growing”and“keep them out”.Described more scientifically，these three procedures are：

1.2.1　Destruction of Microorganisms

Many well-established and several novel procedures are available to kill microorganisms. These include thermal processes such as pasteurisation and ultra-high temperatures sterilisation，and non-thermal processes such as irradiation，high hydrostatic pressure and pulsed electric fields.Most often，pasteurisation involves a cooking or heating procedure conducted at atmospheric pressure.It is used to protect the public health by killing pathogenic microorganisms and to extend product shelf-life by killing spoilage microorganisms.Many foods to be sterilised are packaged into metal，glass or plastic retail containers，hermetically sealed and processed under pressure with steam at 121℃ or higher.Foods may be sterilised at ultra-high temperatures（UHT）for a very short time，e.g.140～150℃ for several seconds.

1.2.2　Prevention of Microbial Growth

The principal process controls to prevent the growth of microorganisms in foods include refrigeration，freezing，modified atmospheres.Below its minimum growth temperature，a microorganism is no longer able to grow.The generally accepted temperature for optimum refrigeration is 5℃ or lower.The shelf-life of refrigerated perishable foods can often be extended by frozen storage.Commercially produced frozen foods are usually stored at -18℃. Some perishable food products are packaged in containers with a headspace for air under atmospheric pressure.Other factors permitting，aerobic microorganisms can grow freely in such products.Their growth can be inhibited or prevented by the removal of headspace oxygen（vacuum packaging）or the addition of inhibitory gases（modified atmosphere packaging）.

1.2.3　Prevention of Contamination

Many potential microbiological hazards can be avoided by preventing cross-contamination. Cross-contamination is the transportation of harmful substances to food by：

Hands that touch raw foods，such as chicken，then touch food that will not be cooked，like salad ingredients.

Surfaces，like cutting boards or cleaning cloths，that touch raw foods，are not cleaned and sanitized，then touch ready-to-eat food.

Raw or contaminated foods are touch or drip fluids on cooked or ready-to-eat foods.

Cleaning and sanitation procedures and personnel practices used in food processing facil-i ties are most important in this regard.

1.3　Control of Chemical Hazards

Food manufacturing facilities should maintain a chemical control plan to prevent contamination of its products with allergens，mislabelled or adulterated ingredients，and cleaning and maintenance chemicals.As with all food safety and quality practices，employee training and awareness is an essential factor in minimising the risk of chemical hazards in foods.For example，these include verification of the accuracy of the ingredient declarations on product labels，and the implementation of suitable prerequisite control for the receipt，storage and use of high-risk ingredients.Quality assurance and production personnel must verify that the ingredients are added correctly to product mixers or preblend operation. Cleaning and sanitation chemicals，pesticides and other non-food chemicals need to be stored in a confined，locked area and not to be used during periods of food production.

1.4　Control of Physical Hazards

There are three principal means to control physical hazards in foods：

Exclusion—including programmes for glass，wood，personnel practices and pest control

For example，most food processing facilities maintain a strict prohibition on the use of glass or brittle plastic instruments，utensils to avoid the possible entry of glass fragments into the food product.Wooden pallets and wooden handles on tools and maintenance equipment used in all production areas need to be excluded.Employees should not wear items of jewellery and should wear uniforms and hair covers.The uniforms should have no pockets，so that items such as pens and pencils cannot be carried in the pockets and fall into the products.Insect activity can be minimised inside facilities by the use of insect light traps that attract flying insects with an ultraviolet light.

Removal—by the use of devices such as magnets，sifters

Many types of in-line magnets are used by food processors on incoming ingredients，processing equipment and packaging operations，both to protect the equipment from damage by tramp metal and to avoid product contamination.Sifters and sieves are often used to separate foreign materials from dry food materials.

Detection—by using instruments such as metal detectors，X-rays and optical sorters

Several technologies are available to detect the presence of foreign materials in a food. The most common of these are metal detectors that can be used online or for packaged products.With image-enhancing capabilities，X-ray devices can be used to detect dense foreign material inside food products，such as bone chips in meat products.Optical technologies，using visible or ultraviolet light，are used with fruits，vegetables and nuts to detect surface defects and the presence of extraneous vegetable matter，stones，etc.

Technical Terms

foodborne disease　食源性疾病

pathogenic bacteria　病原性细菌

fungi［］n.　真菌

virus［］n.　病毒

prion［］n.　感染性蛋白质

protozoan［］n.　原生动物

helminthic parasite　蠕虫寄生虫

intoxication［］n.　中毒

gastrointestinal［］adj.　胃与肠的

diarrhoea［］n.　腹泻

allergen［］n.　过敏源

mycotoxin［］n.　毒枝菌素，真菌毒素

alkaloid［］n.　生物碱

phytohaemagglutinin［］n.　植物血凝素

pesticide［］n.　杀虫剂，农药

fertilizer［］n.　肥料，化肥

antibiotic［］n.　抗生素，抗菌素

lead［li：d］n.　铅

cadmium［］n.　镉

mercury［］n.　汞，水银

arsenic［］n.　砷，砒霜

uranium［］n.　铀

lubricant［］n.　润滑剂，润滑油

refrigerant［］n.　制冷剂，冷冻剂

plasticizer［］n.　增塑剂，可塑剂

vinyl chloride　氯乙烯

adhesive［］n.　黏合剂

tin［tIn］n.　锡，马口铁

thermal processes　热处理

pasteurisation［］n.　巴斯德杀菌法

sterilisation［］n.　消毒，灭菌

non-thermal processes　非热加工

high hydrostatic pressure　高静压技术

pulsed electric fields　脉冲电场

ultra-high temperatures（UHT）　超高温

refrigeration［］n.　冷藏

freezing［］n.　冻结，结冰

frozen storage　冻藏

vacuum packaging　真空包装

modified atmosphere packaging　气调包装

ready-to-eat food　方便食品，即食食品

cross-contamination　交叉污染

sanitize［］v.　进行消毒

cleaning and sanitation procedures　清洗消毒步骤

adulterate［］v.　掺假

sifter［］n.　筛具

Exercises

Ⅰ.Answer the following questions according to the article

1.What is the definition of a foodborne hazard？

2.What do biological hazards mainly include？

3.What disease systems can be caused by chemical hazards？

4.How to control microbiological hazards？

5.List some measures that can be taken to control physical hazards.

Ⅱ. Choose a term from what we have learnt to fill in each of the following blanks. Change the word form where necessary

1.Foodborne hazards can be individed into ________，________and ________ three categories.

2.________，________ and ________ foods are classified as potentially biological hazardous because these foods can support rapid growth of infectious or disease-causing microorganisms.

3. Microorganisms in food materials can be killed by thermal processes such as ________，and non-thermal processes such as ________.

4.________ are naturally occuring protein to which some person develop a hypersensitivity or immunological response.

5.Peanut product producers use ________ to remove dark-coloured nuts，thereby reducing the risk of aflatoxin contamination in finished products.