ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

How to Control Biological Hazards and Food Quality?

Updated on September 14, 2011

Food Quality

Biological Poison in Your Food

Factors Affecting the Growth of Biological Hazards

The major factors affecting the Growth of Biological Hazards include;

· Intrinsic Factors

· PH

· Moisture

· Nutrients

· Antimicrobial Constituents

· Biological Structures

· Extrinsic Factors

1. Temperature

2. Humidity

3. gases

Intrinsic Factors

Intrinsic factor are the inherent parts of food. This is natures way of preserving plant and animal tissue from microorganisms. By determining the extent to which they exist in a given food, we can predict the types of microorganisms that are likely to grow and hence the significance of the hazards for a particular food or food group. The following is an explanation of the intrinsic factors we most commonly use in order to reduce the growth of microorganisms.


In the unprocessed state, most foods such as meat, fish and vegetables are slightly acidic, fruits are moderately acidic, and a few foods such as egg whites are alkaline. Acidity has been a commonly used means of preserving food for thousands of years either naturally, through fermentation, or by the addition of weak acids (pickling).

Most microorganism grow best in the pH range of 6.6 to 7.5. Few microorganism grow at a pH of less than 4.0 Bacteria tend to prefer narrower ranges of pH than molds and yeasts, the pathogenic bacteria being the most fastidious. In general, molds and yeasts grow at a much lower pH than bacteria.

Moisture Content

Another one of man’s oldest methods of preserving food is to dry it. The water requirements of microorganisms is defined in terms of water activity (aw). Water activity is a measure of the water present in a form that is available to microorganisms. The water activity of a substance can range from 0 to 1. Water has a water activity of s1.0, silicon has a water activity of 0.

The aw in a food or solution may be reduced by removing water or adding solutes. When we dehydrate food we remove water. When we salt or add sugar to food we are adding solutes which lower the water activity and preserve the food.

The aw of most fresh foods, is greater than 0.99. in general, bacteria require higher water activity levels for growth than molds. Most spoilage bacteria do not grow below aw 0.91. Spoilage molds can grow as low as aw 0.08. These figures apply for most, but not all microorganisms, in the case of food poisoning bacteria, Staphylococcus aureus can grow at a water activity level as low as 0.86. Halphiles (literally”salt loving”) are bacteria that can grow at aw 0.75. xerophiles (“dry loving”) molds can grow at aw 0.65. Microorganisms are able to survive at a wider range of water activity levels than those required for their growth.


Microorganisms may utilize suggers, alcohols, and amino acids as sources of energy. Fewer types of microorganisms utilize carbohydrates and fats. Most microorganism require B vitamins in the food in order to grow. Moulds and some bacteria are able to synthesize most or all of the B vitamins the require and hence may be found on food low in B vitamins such as fruit.

Antimicrobial Constituents

Some foods naturally contain substance that inhibit the growth of microorganisms. Cows milk, eggs, tea, fruits and vegetables all contain antimicrobial constituents.

For example, just two of the antimicrobial constituents in eggs are:

· Lysozme-an enzyme which destroys gram positive bacteria; and

· Certain proteins-which stop microorganisms from being able to use riboflavin and vitamin B6 as a nutrient.

Biological Structures

The natural covering of some foods provides good protection against the entry of microorganisms. Examples are the testa of seeds, the skin on fruit, the shell of nuts, the hide of animals, and the shell, cuticle and membranes of eggs. Once broken, of course, the risk of the food being spoilt is increased.

Extrinsic Factors


Throughout the ages, humans have learned by trial and error ro exploit temperature in order to preserve food. Today, temperature is one of the most commonly used and critical factors in the production of food ;that is safe to eat.

Although microbial growth can occur between 340C to over 900C, most microorganisms grow within a smaller range. It is customary to place microorganisms into three groups based upon their temperature requirements for growth.

Classification Temperature Range for Growth Optimum Temperature Range Examples

Psychrophils Below 200C S120Cto 150C

Physchrotrophs Below 350C 250Cto 300C Pseudomonas ,Listeria ,Yersinia

Mesophiles 50C to 4760C 30Cto 450C Salmonella Staphylococcus

thermophiles Above 400C 550Cto 750C Clostrtidium Bacillus

Just as moulds are able to grow over wide ranges of pH, water activity, and nutrient content, they are also able to grow over wider ranges of temperature than bacteria. Yeasts grow over the psychrophilic and mesophilic temperature ranges but generally not in the thermophilic range.

General quality characteristics, not just the safety, of the food must also be taken into account in selecting a storage temperature. For example, bananas keep better if stored at 130C to 170C than at 50C. A large number of vegetables are favored by temperatures of approximately 100C including potatoes, celery and cabbage.

The success of storage temperature depends to a great extend on the relative humidity of the storage environment.

Relative Humidity

The relative humidity is important in terms of the water activity of the food and the growth of microorganisms at the surfaces. If the water activity of a food is 0.60 and it is stored in a humid environment it will pick up moisture from the air and increase its water activity to a point where microbial growth can occur.

Foods such as chicken and meat tend to suffer from surface spoilage if improperly wrapped in the refrigerator do to the generally high humidity. In selecting the right relative humidity consideration must be given to both the growth of surface microorganism and the desirable quality of the food in its other aspects. Food stored under low condition of relative humidity may not be spoil by surface microbes but will become dry.


Carbon Dioxide

The storage of fo0od in atmospheres containing up to 10% carbon dioxide is referred to as “controlled atmosphere” storage. This method is commonly used for fruits and vegetables. Carbon dioxide has been shown to retard the fungal rotting of fruits.


Ozone has a preservative effect on certain foods when added to the storage environment. It is effective against a wide range of spoilage microorganisms. Both CO2 and O3 are effective in inhibniting the spoilage of beef.

Sulfur Dioxide

Sulfur dioxide (S02) is applied to food and beverages as a liquefied gas, or more commonly, in the form of sulfite, bisulfite, or metabisulfite salts.

Aerobes Require oxygen in order to grow. Hence they grow on the exterior of foods. Bacillus subtilis Psuedomonads

Facultative Anaerobes Use oxygen in its presence but in its absence can still grow. Hence they can grow on the surface and interior of foods. Lactobacilli

Anaerobes Grow in reduced oxygen environment. Hence they prefer to grow in the interior of foods. Clostridium


    0 of 8192 characters used
    Post Comment

    • profile image


      3 years ago

      Have you ever considered aiddng more videos to your blog posts to keep the readers more entertained? I mean I just read through the entire article of yours and it was quite good but since Im more of a visual learner,I found that to be more helpful well let me know how it turns out! I love what you guys are always up too. Such clever work and reporting! Keep up the great works guys Ive added you guys to my blogroll. This is a great article thanks for sharing this informative information.. I will visit your blog regularly for some latest post.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)