Food Processing and Foodborne Illness

Introduction

Food processing means manipulation of raw materials from plants or animals into food. Since agriculture and animal husbandry

were established postharvest procedures were necessary to preserve for a longer time the increasing food supplies coming from the

fields and domesticated animals. Food is one of the best culture medium for a lot of microorganisms and preventing food spoilage

caused by enzymes and microorganisms is crucial. Deterioration of food is caused mainly by three natural processes:

1. Oxidation – vegetables after harvesting or meat after animal slaughtering get in contact with the oxygen in the air that makes

them rancid and unpleasant.

2. Enzyme action – all food contains natural enzymes that break down proteins, fats, and carbohydrates to their simple components

until but food spoilage if left uncontrolled.

3. Microbial action – all food can be attacked by bacteria and fungi that cause food spoilage and release toxic components.

The first methods of food processing were based on some chemical procedures like adding salt to meat, sugar to fruit, reaching an

acidic pH, storing in alcohol. High temperatures were also used to exsiccate food. The basic action of these procedures is the reduction

of water activity (aw). The metabolism of all living cells is based on aqueous environment and all enzymes have reduced or no

activity in substrate in low water content. However, the original taste and several nutritional organoleptic characteristics are usually

lost with these procedures. Low-temperature conservation (refrigeration and freezing) prolonged fresh food properties but psychotropic

(cold-resistant) organisms can be still dangerous i.e., Listeria monocytogenes and Yersinia enterocolitica.

Microbiological safety of food remains a dynamic situation influenced by multiple factors and food safety standards depend on

constant monitoring and surveillance from farm to fork. Food is an excellent vehicle for well-recognized bacteria i.e., Salmonella,

Campylobacter, and L. monocytogenes and virus such as norovirus, hepatitis A, rotaviruses. However, less prevalent pathogens and

rare agents like prions and new alarming topics such as antimicrobial resistance in foodborne pathogens (Salmonella, Campylobacter,

Shigella, methicillin-resistant Staphylococcus aureus, Escherichia coli) are relevant for policy-makers. Many parasites are also transmitted

through food (i.e., Toxoplasma gondii, Cryptosporidium, and Trichinella) but effective monitoring is not performed for most

of them in foodstuff, livestock, and food process establishments. Additionally, some parasitic infection such as trichinellosis is often

transmitted through the meat of game animals.

Food Processing

Until the industrial revolution, food production remained rudimentary and people were consuming essentially their own or neighbors’

productions. Nowadays food processing is not only a way to preserve the food, but also to satisfy an increasing demand for

convenient and various foods (van Boekel et al., 2010). Modern food industry ensures an enormous food variety since food from

different countries can be eaten worldwide at any time. Even special dishes of typical cuisines (pasta, pizza, sushi, hamburgers) are

internationally prepared and consumed. Local food is linked to seasons but in a globalized world food can be easily transported all

over in a short time. Largely consumed food in a country is often the most imported from other countries due to the high request

and insufficient internal production.

Food processing is used for the preservation of taste, smell, look, and safety of food by inactivating the basic natural processes of

spoilage. To this end, microbial enzyme preparations are also used, containing the active enzyme but also other metabolites of the

producer strain and food-grade additives (preservative and stabilizers). Fungi (i.e., Aspergillus niger) are used in industrial fermentations

to prepare large quantity of enzyme preparations such as alpha-amylase, catalase, cellulose. However, they might be at risk

for toxins production (mycotoxins) which are species-specific products of the secondary metabolism (metabolism of the stationary

phase of growth). To ensure food safety grade, fungal enzyme preparations have to be tested for the species-specific mycotoxins in

closely related species i.e., aflatoxins in Aspergillus oryzae and Aspergillus flavus (Blumenthal, 2004). In recent years, the enzymes

producers, microorganisms, can be modified through genetic technologies (Olempska-Beer et al., 2006). However, only nonpathogenic,

nontoxigenic microbial strains must be considered to generate safer lineages with improved characteristics through genetic

modification (Pariza and Johnson, 2001).

Primary and Secondary Processing

Various levels of processing are performed to prepare the huge variety of food products available at the present time. While a simple

and rapid pasteurization process is requested for milk, more procedures are necessary for dairy products. All processing procedures

can represent critical points in which contamination of food might occurs from the environment and/or food operators i.e., fruits or

vegetables during washing by contaminated water and meat at the abattoirs by pathogens from the animal intestines. Complex food

matrices like food preparations or ready to eat food can be contaminated from multiple sources.

The preliminary step for all food products is the collection fromthe primary sources: vegetables harvest, slaughtering livestock,milk

or eggs collection, catching fishes, and game animals. All these raw foodsmust be at least cleaned, cut, sorted, graded, packed, and refrigerated

to prevent microbial growth and spoilage. These procedures represent the primary food processing which implies a short chain

(Figure 1) with a relative low number of operators from the harvest to the consumers’ home; in contrast, several steps are performed for

the final products in secondary processing (i.e., canned meat and vegetables, fruit juices, fully prepared dinners). Big, medium, and

small food industries are involved to prepare the multiplicity of different food products through manual or automatic steps.

Food processing has been changing throughout the history continuously adopting new technologies and maintaining the old

and effective ones. The following procedures (from the ancient to more recent) are applied to different kind of food.l Salting is performed since ever to preserve food for longer period. The basic principle is the removal of water through an osmotic

process.

l Exsiccation to reduce water content in food, such as meat, fish, cereals, powdered milk, and soups.

l Smoking to dry the food often adding extra flavors and ensure longer shelf life to fish or cheese.

l Fermentation is the process by which microbes produce alcohol or acid, which act as preserving agents. Yoghurt, beer, wine are

typical examples.

l Food additives – Additives or preservatives can lower the Ph (acid environment) to protect the food against spoilage; emulsifiers

are used to stop the clotting of fats, antioxidants to avoid food becomes rancid, etc.

l Pasteurization consisting on heat treatment at 72
C for 15 s followed by quickly cooling to 5
C. It makes a long shelf life for

beverages (milk and fruit juices) but refrigeration is still required.

l Sterilization with temperatures of 120
C for few seconds followed by a rapid cooling step. This treatment kills most microbes

and inactivates enzymes ensuring a longer shelf life than pasteurization and no need for refrigeration until the package is open.

l Refrigeration and freezing maintain food at controlled, low temperatures to inhibit enzymes activity and microbial growth but

temperature control is critical and the overcome of psychotropic bacteria like L. monocytogenes must be avoided.

l Irradiation with electron beams, X-rays, and gamma rays is a process that kills spoilage organisms and pathogenic bacteria in

a variety of fruits and vegetables. Fresh produce may be irradiated to inhibit sprouting, to delay ripening, to sterilize or kill insect

pests, or to reduce microbial populations (Moosekian et al., 2012).

Food Poisoning and Allergies

In food poisoning illness, toxins with different chemical and biochemical properties from several sources are involved. Toxins can be

produced by bacteria (i.e., Staphylococcus, Clostridium, Bacillus), shellfish, fishes, mushrooms. They may result in acute illness such as

emetic reaction, gastroenteric symptoms, neurologic reactions. Fungal toxins are species-specific products and can cause a variety of

symptoms fromgastric upset (vomit and diarrhea) to life-threatening organ failures. Serious symptoms might not occur immediately

after ingestion but days or weeks later. In the case of alpha-amanitin (toxin from Amanita), death for liver failure occurs in 1–3 days

after ingestion. Microscopic fungi (i.e., Aspergillus) involved in food enzyme preparations (see above) can also produce mycotoxins

such as aflatoxin B1, zearalenone, and the most toxic ochratoxin A, a nephrotoxic and carcinogenic compound (Abarca et al., 2001).

The allergies are excessive immune reactions to nonpathogenic molecules. The majority of food allergies are caused by allergens,

present in common foods such as peanuts, soy, tree nuts, milk, egg, seafood. Sensitized people are at risk for dangerous reactive reaction

up to death for anaphylactic shock. Besides the note on its presence in the labels, the allergen risk management in food

manufacturing should start at the primary processing to minimize the possibility of allergen contamination in finished food products

(Alvarez and Boye, 2012).