In developing countries agriculture is the mainstay of the economy. There should be no surprise that agricultural industries and related activities can account for a considerable proportion of their output. Of various types of activities that can be termed as agriculture based, fruits and vegetable processing are among the most important. Fruits and vegetables, which are among the perishable commodities, are important ingredient in human diet. Due to their high nutritive value, they make significant nutritional contribution to human well-being. They are cheaper and better source of protective foods. These contain non-nutritive secondary metabolites known as phytochemicals that have disease-fighting properties. Some of these phytochemicals are polyphenols, pigments (e.g., carotenoids) and glucosinolates.
Fruit and vegetable production and processing involve a complex supply chain from the farm to fork. From many points of view, it is of great importance to strengthen each link in the chain and improve the integration of the supply chain if high quality and safety of produce must be maintained. International trade of fresh fruits and vegetables is a billion-dollar business that has significantly increased in the last decade. This trade is important also from a safety viewpoint, and involves (primary) producers, manufacturers, distributors, and retailers who place a great deal of value on their reputation for marketing naturally delicious and nutritious products. Safety of fruits and vegetables starts with agriculture and primary production. One major factor leading to food contamination during food preparation and storage is time–temperature abuse, which results in the survival, growth, and production of toxins by pathogens. In recent decades, microbial safety has become a concern and a series of large foodborne outbreaks has occurred around the world. The situation is more alarming due to several population explosion, urbanization and changes in lifestyle, consumption of, so-called, minimal processed ready-to-eat foods, international trade in food and animal feed, international tourism and immigration, and a short supply of potable drinking water.
- Types of Hazards
Fruit and vegetable contamination problems can occur in the growing environment, after harvest, during preparation for storage and processing, shipping to the market and in the home. Many hazards may enter the food supply, making the food potentially harmful when consumed. They can cause injury or illness in the absence of their control. These foodborne hazards could be divided into three categories: biological, chemical, or physical.
- Biological Hazard
Biological hazards include pathogenic fungi, bacteria, viruses, prions, protozoans and helminthic parasites, namely certain trematodes. These could cause foodborne illness due to pathogen–host interaction. Pathogens most associated with fruits and vegetables include Salmonella, Shigella, Escherichia coli O157:H7, Listeria, Campylobacter, Cryptosporidia, viruses such as Hepatitis A and parasites such as Entomoeba histolytica, Giardia lamblia, Cyclospora cayetanensis, Cryptosporidium parvum, Toxoplasma gondii, and certain trematodes. There are certain sources/factors that contribute to the microbiological contamination of these products with pathogens, all of which must be controlled. Contamination can arise because of treating soil with untreated manure and sewage sludge, untreated effluent water released from meat industry and from irrigation water. Additionally, handling and the application of technologies such as cutting, slicing, skinning, and shredding (in the case of minimally processed fruits and vegetables) will remove the natural protective barriers of the intact plant and open the possibility for providing a suitable medium for the growth of contaminating microorganisms. The numbers of bacteria present in fruits and vegetables will vary depending on seasonal and climatic. Shredding and slicing were found to increase counts of mesophilic bacteria.
- Physical Hazards
Physical hazards are commonly called “foreign materials” or “foreign bodies” because their presence in food is unnatural. They include unwanted t field matter (stones, wood, metal, pieces of bone, insect fragments, etc.); inadvertent processing residues (glass, metal fragments, pieces of plastic, personal objects, etc.); unintentional materials (employee sabotage) and miscellaneous particulates and fragments or food itself (pits, stones, stems). These may enter foods at almost any point of the food supply. Some foreign matters may not act as a hazard but their finding in food may be indicative of poor hygienic practice and a distressing event for consumers.
- Chemical Hazard
Chemical hazards may appear in food products either by natural occurrence (e.g. naturally occurring toxin in certain mushrooms, solanine in potatoes) in a raw material or by deliberate or unintentional addition during primary production and/or processing. They could result from several sources: the environment such as heavy metals or radionuclides; agricultural chemicals such as insecticides, fungicides; packaging materials; cleaning/sanitizing agents; certain toxins; and misuse of food chemicals. Control of chemical hazards along the food chain is of primary importance as the consumer has no opportunity to reduce them substantially during food preparation.
- Adoption of Good Agricultural Practices at Primary Producing Stage
- Soil can contain harmful microbes that can contaminate crops. Soil can be tested before each planting and remediation completed if it contains harmful microbes called pathogens.
- Contaminated water is one of the most common sources of microbial contamination of crops. Before selecting a field location, growers should examine upstream uses of irrigation water that could lead to contamination. They should also select an area that’s free from flooding or run-off.
- It is generally recommended not to irrigate crops for two to seven days before harvest. If water used for irrigation was contaminated, this gap without water provides adequate time for any present harmful pathogens to likely die before the crop is harvested.
- It is not uncommon for manure and other biosolids to contain harmful pathogenic microbes if it is not treated before use. Raw manure should be stored in a separate area from crops and with protection to prevent accidental cross-contamination from occurring. If manure is used as a natural fertilizer on a field crop, it is best practice to wait 120 days before harvesting the produce.
Adoption of Good Manufacturing/ Production Practices at Processing Stage
- Loading docks should be kept clean and free of grass, dirt or outside debris. When not in use, loading docks should be closed and locked to ensure outside pests or traffic cannot enter the processing facility.
- Any food contact surface should be cleaned and sanitized regularly to prevent cross-contamination or spreading of microbial contamination. This includes counters where food is prepared and tools such as knives and machines used for processing produce.
- Gloves should be worn when handling produce, and employees should practice good personal hygiene. Restrooms and employee break rooms should be in a separate area from anywhere produce is processed.
- While it is important to visually check the cleanliness of food contact surfaces, harmful bacterial pathogens are microscopic and cannot be seen with the naked eye. That is why regular testing for microbes on food contact surfaces is essential to identify and minimize any areas contamination.
- Good Manufacturing Practices (GMP) and Hazard Analysis and Critical Control Points (HACCP)are essential and effective measures for identifying and controlling risks during produce processing. Creating a written preventative plan is an essential step for food manufacturing safety.
- Blanching is the process of quickly and briefly boiling or steaming vegetables or fruit. Blanching is an effective method to inactivate enzymes and damage microbes before freezing which can limit deterioration of the produce.
- After blanching produce, it should be frozen rapidly. Reducing the temperature of the product quickly will prevent it from further cooking and help ensure the continued freshness of the product while also slowing the activity of any microbes that might be present.
- Another effective technique for stopping enzyme activity in frozen produce is by addition of ascorbic acid, commonly known as vitamin C, to prevent any further chemical deterioration.
Knowledge of the nature of fruits and as they relate to pre and post-harvest handling, processing, packaging and storage are essential for ensuring their wholesomeness and nutritional value, and for developing the most effective procedures and innovative technologies for maintaining their quality and safety.