CAN FRESH PRODUCE "ABSORB" PATHOGENIC BACTERIA AND VIRUS? A DEBATING POINT

Contrary to the strong belief that plant foods are less vulnerable to contamination with bacteria and virus, an analysis of food poisoning episodes due to pathogens during the last one decade clearly shows that they can be equally at risks as the meat products are in contracting infection from the field. Too much attention to animal farms, abattoirs and poultry farms by the safety monitoring authorities probably ignored the potential for microbial contamination of plant foods from the growing areas through water, soil and manure. It was rather startling to note that almost half the food poisoning episodes in the world originated in plant foods like leafy greens, cantaloupes, mangoes, strawberries, peanuts, walnuts and others causing significant mortality among consumers. This situation probably calls for a more vigorous study to get a better insight into this reality. 

The cultivation practices and the farm land locations do contribute to the vulnerability of agricultural crops to microbiological contamination. Inputs like water, and manure can be critical in maintaining freedom from pathogens while proximity to animal and poultry farms and sewage processing facilities makes the plant crops doubly susceptible to cross contamination with high probability. If the cultivated area is near to forest areas visits by animals during nights cannot be entirely avoided and their fecal droppings are a strong source of microbes of different types with varying pathogenicity. There is also the possibility of pathogens getting on vegetables and fruits in processing facilities where they are cleaned up and packed for distribution to super markets. Storage and distribution facilities if not properly sanitized frequently can cause cross contamination. In the absence of reliable traceability regime it may e next to impossible to pin point the source of contamination.

A revealing fact is that in most contamination episodes with fruits and vegetables the pathogens are found mostly on the surface though no studies have ever been carried out to find out whether these bacteria are present inside also and if so how deep they are inside. It will be a terrible tragedy if contaminating organisms find their way inside the plant and the crops through the root system. After all the fields where plants are grown can have billions of microorganisms belonging to hundreds of different species, most of them benign but some highly pathogenic. It has  to be remembered that the deadly E.coli O157:H7 strain which caused many poisoning episodes during the last few years originated in the field where soil was contaminated with fecal droppings of animals like deer and pigs. In spite of so many studies taken up to find whether disease causing bugs like bacteria and viruses can really be absorbed by the roots to be ending up in edible parts of the plant, no evidence had surfaced which support the theory that they might enter the plant under right circumstances.

It is true many bacteria show an ability to migrate towards the roots of many plants but they stay just there without migrating into the internal parts of the plant. Yet they do posses the potential to spread to other external parts of the plant during harvesting and cleaning. This is the reason why new food safety laws being enacted in some countries stipulate that for ensuring safety of fresh produce it is imperative that pathogen free water is used for irrigation and washing, the equipment and machinery deployed do not harbor pathogens and the farm workers are provided with clean water for washing their hands clean during all farm operations. In fact growing of organic foods is an ideal model for main stream agriculture community to emulate for keeping their produce free from disease causing microorganisms. Probably world is moving slowly to a stage where fresh produce which are consumed without cooking are grown only under strictest environmental and field conditions that will not give any scope for contamination with bacteria like Listeria, Salmonella and E.coli O157:H7.

When food borne diseases are discussed there is a unique creature that causes more than 60% of food poisoning episodes which has not received much attention at the hands of food microbiologists and this is the ubiquitous Noroviruses which can contaminate foods during handling stage. It was recently discovered that these viruses have the uncanny ability to contaminate surface areas of fruits and vegetables and normal washing may not be that much effective in getting rid of them easily. This is all the more true with leafy greens like spinach and lettuce which have many openings on the leaf surface called stomata for regulating transmission of gases and water vapor. The guard cells which are located on the surface of the cells can be penetrated easily by viruses,  provide a safe place for the viruses especially when there is a film of water on the surface. Standard washing procedures are not effective in gorging them out and if the contamination density is high, such consignments can cause poisoning episodes when sold in the retail market. Probably in such cases prevention is better than cure and there is no alternative but to guard against contamination at every stage of handling them to exclude incidence of Norovirus contamination.                    

V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com

E.COLI FOOD CONTAMINATION-ASSUMING ALARMING PROPORTION?

The ubiquitous Escherichia coli (E.coli) had never posed any danger to humans until new strains were discovered a few years ago with potential to be dangerous to consumers. Interestingly this bug was routinely being tested as a marker for testing foods for possible contamination with fecal matters during production and handling. The group of E.coli coming under the Enterohaemorrhagic (EHEC) category can cause serious food poisoning, if the food is not properly processed to kill them and it is known to cause even death if not immediately treated. One of the most virulent strains under EHEC is the notorious 0157:P7 which was found to be a major culprit in almost all food poisoning cases in the West.

E. coli belongs to bacterial species and it has been found commonly in the gut of humans and warm-blooded animals. Historically most strains of E. coli are harmless. Enterohaemorrhagic E. coli is an exception in that it can cause severe food borne disease. It is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products and raw milk. Its significance as a public health problem was recognized in 1982, following an outbreak in the United States of America. EHEC produces toxins, known as verotoxins or Shiga-like toxins because of their similarity to the toxins produced by Shigella dysenteriae. EHEC has the amazing capacity to grow in a wide range of temperatures from from 7°C to 50°C, with the optimum temperature being 37°C. Some EHEC can grow in even in acidic foods, with pH as low as 4.4 and in foods with a minimum water activity (Aw) of 0.95. It can be destroyed completely by adequate cooking of foods to ensure that all parts reach a temperature of 70°C or higher. E. coli O157:H7 is the most important EHEC serotype in relation to public health, though other serotypes are also emerging causing occasional outbreaks.

Symptoms of the diseases caused by EHEC may include abdominal cramps, diarrhea, fever and vomitting. It may take any where from three to eight days for the bacteria to be fully incubated and act in human body though most cases can be diagnosed within three to four days. When properly treated the affected person can recover within 7-10 days, though in a few cases, especially when young children and old people are affected the infection can be life-threatening. Haemolytic uraemic syndrome (HUS) one of the diseases caused by this bug is characterized by acute renal failure, haemolytic anaemia and thrombocytopenia. It is believed that up to 10% of patients with EHEC infection may develop HUS, with a fatality rate ranging from 3% to 5%. It can cause neurological complications including seizure, stroke and coma in about 25% of HUS patients and chronic renal sequelae in around 50% of survivors. Some of the outbreaks due to EHEC have involved a high number of cases, such as in Japan in 1996, where an outbreak linked to contaminated radish sprouts in school lunches affected thousands of children. Data on the situation in most developing countries are limited, as surveillance for this pathogen is not done routinely and documentation practices are not in vogue.

Why is that EHEC infection is reported more commonly in Western countries and other affluent populations where hygiene and sanitation awareness is very high? Why is that this infection does not affect people in countries like India where food crops are cultivated in rural areas where open defecation is practiced with high probability of the crop getting contaminate? Probably because Indians consume almost all their foods in overcooked conditions while the salad eating practice based on raw vegetables is prevalent in the West.The serotype O157:H7 which has been studied extensively, is easily differentiated biochemically from other E. coli strains. Interestingly this bug is present in great numbers in cattle and other ruminants such as camels and is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products and raw milk.

Fecal contamination of water and other foods, as well as cross-contamination during food preparation containing beef and other meat products, contaminated surfaces and kitchen utensils, will also lead to infection. Examples of foods implicated in outbreaks of E. coli O157:H7 include undercooked hamburgers, dried cured salami, unpasteurized fresh-pressed apple cider, yogurt, cheese and milk. What is worrying the food safety experts is that increasing number of outbreaks are now being associated with the consumption of fresh horticultural produce like sprouts, lettuce, coleslaw, tomato, cucumbers, salad etc, which are eaten raw without thermal processing. Possibly these fresh produce materials are contaminated due to contact with feces from domestic or wild animals at some stage during cultivation, handling and storage.

EHEC has also been isolated from bodies of water (ponds, streams), wells and water troughs, and has been found to survive for months in manure and water-trough sediments. Waterborne transmission has been reported, both from contaminated drinking-water and from recreational waters. Organic foods which are produced using natural manure can be most vulnerable to infection by EHEC. Person-to-person contact is an important mode of transmission through the oral-fecal route. There are also instances where infected individuals show no clinical signs of disease but pass on the infection to others. The duration of excretion of EHEC from the body is about one week or less in adults, but can be longer in children. Visiting farms and other venues where the general public might come into direct contact with farm animals has also been identified as an important risk factor for EHEC infection.

The most recent episode of EHEC food poisoning comes from Austria where many consumers were infected by consuming organically grown vegetables from Spain and that country's food safety agency has cautioned the consumers about the dangers of consuming these tainted fresh produce, advising them further to destroy such dangerous bacteria containing products. Some of the vegetables under the scanner include cucumbers, tomatoes and aubergines. There are reported to be 10 casualties in Germany due to this episode and other member countries of EU are gearing up to tackle this contingency without causing major damage to their citizens. The classical belief that only animal products are contaminated by EHEC needs to be reexamined in the context of such episodes involving fruits and vegetables. Probably predominantly meat consuming countries are vulnerable because of improper management of production farms due to shortage of personnel and over mechanization of many operations. Though meat products are segregated during storage, distribution and retailing there can be cross contamination from these foods affecting fresh produce like fruits and vegetables.

V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com

"RAITHA SANTHE"(FARMERS' MARKET)-THE NEW SYMBOL OF GROWER-CONSUMER BHAI BHAI!

The woes of growers in India are well known and no wonder more and more of this breed are finding life miserable due to poor returns from their avocation. Small land holdings, difficulty to access easy source of short term finance, uncertainties of weather, poor infrastructure, wide spread operation of middlemen who deny reasonable prices for the crops all contribute to the miseries of the farmer. While durable foods like cereals have Minimum Support Price (MSP) scheme of the government, guaranteeing reasonable returns for their crops, the perishables suffer from seasonal price fluctuations and demand-supply uncertainties which cannot be surmounted unless low temperature storage and transport facilities are available at affordable cost. The fear of perishability and glut in production invariably have a price depressing effect making cultivation of these foods a "professional hazard". To add to these difficulties, there is no insurance scheme that will compensate for crop loss due to circumstances beyond the control of the farming community.

The Fruit and Vegetable project taken up by National Dairy Development Board, Anand in the mid-1980's addressed the problems of the growers by establishing cooperative societies in growing areas and processing facilities combined with selling net works in urban areas like New Delhi. Unfortunately the project has not been able to achieve any spectacular success similar to the milk project which made India the top producer of this vital food in the world. In Karnataka itself, Horticultural Producers' Cooperative (HOPCOMS) did commendable job by linking producers directly with the consumer but has not been able to make any significant impact in the market. Organized retailing players owning huge sales outlets in major metropolitan areas did raise hope that their economic and organizational clout would benefit both growers and the consumers by eliminating middle men. But the results so far have belied that hope.

Weekly shandies organized in different rural areas are serving the purpose of providing an opportunity to village folks around the area to expose their products including fresh foods to buyers hailing from nearby settlements at very reasonable prices. These shandies serve a very useful purpose in that both consumers and farmers are mutually benefited. What puts off the buyers, how ever, is the unorganized, dusty, unclean and poor facilities and many potential customers do not opt for such an adventure fearing about diseases and allergies. With no facilities for drinking water or toileting or even for resting for some time without being exposed to the Sun, senior citizens and elderly customers do not consider such places worth visiting, denying them the benefits of buying fresh fruits and vegetables at bargain prices. Added to this the transportation facility to such shandies is very limited.

In Mysore growers of fruits, vegetables and similar fresh food materials gather every day on the side of a half kilometer stretch of a road offering their wares in bargain prices and more than hundred such farmer-vendors participate in this "unofficial' market to cater to the needs of thousands of buyers who regularly congregate at this point to get their daily needs of fresh foods. Same logistical problems that face the rural weekly shandies are experienced here also, with no civic authority officials bothered about such gross neglect. Thanks to some sudden awakening amongst the babus who control the destiny of people in a city like Mysore with two plus million population, a grandiose plan has just been announced for establishing a permanent Farmers' Market (Raitha Santhe) in a nearby vacant place with modern facilities.

According to the plan made public recently, there will be 400 sheltered "stalls" for allotting to genuine farmers for a season so that he can bring his produce directly to the market without the help of any "commission agent" and get maximum price. The proposed Market is expected to have decent civic amenities including parking area for modern day consumers to enjoy the experience of buying "straight" from the farmer at reasonable prices. Major difference between this type of market and the traditional markets is that the latter is controlled by middle men, harvest contractors, "muscle" people etc with high speculative and money power. Even if the produce is perishable the sellers in to day's market system do not reduce prices, not bothered about the wastage at the end of the day. The cold storage facilities are also used by these middlemen to hoard some less perishable produce to manipulate the market prices. Hopefully such things will not happen in the new facility to be built exclusively for farmers. Long live the newly evolving "farmer-consumer" bhai bhai relationship!

V.H.POTTY
http://vhpotty.blogspot.com/
http://foodtechupdates.blogspot.com

NON-THERMAL PATEURIZATION-FUTURISTIC TECHNOLOGY

Cold sterilization and pasteurization processes are generally based on gamma radiation or X-Ray exposure at ambient temperature without recourse to heating. They have the unique advantage of not affecting the organoleptic quality or the nutrient content of the foods processed. How ever both these technologies are viewed with suspicion by the consumers because of the use of radiation energy which is mistakenly being associated with the lethal Hiroshima Atom Bomb responsible for the death and miseries of thousands of people during World War II. Tons of scientific data have been generated to prove the absence of live radiation in the products treated and more than 40 countries have cleared the use of gamma radiation in selected foods for both indigenous consumption as well as for exports. As for X-Ray treatment, it is a young technology, yet to take off, with lot of promises.

Food contamination with pathogens like E.coli, Salmonella, Listeria, etc is assuming alarming proportion in some of the developed countries in the American and European continents in spite of strict vigilance and the much acclaimed monitoring systems in place. Yet these countries could not prevent the outbreak of E.coli infection in spinach in 2006 in USA killing 3 people and sickening another 200. In USA alone 40000 cases of Salmonellosis per year are being reported killing at least 400 people and 70000 cases of E.coli infection resulting in dozen fatalities. The recent Salmonella contamination reported in Peanut products made in USA, requiring calling back of millions of dollars worth of products containing peanut paste or butter as an ingredient, is still fresh in our memory, hitting hard the credibility of their safety monitoring machinery.

Most difficult materials to be decontaminated are fresh farm produce as they suffer significant quality damage if standard thermal treatment regime is adopted. Though Salmonella is associated more with fish and meat products, their presence in fresh produce is suspected to be due to careless farm practices and indifferent handling in the packing sheds. Treatment with chlorine does help to some extent but this is not a fool proof practice and post-treatment cross infection can still take place with potential hazard to the consumer. Food chain accountability being lax in many countries, it is becoming increasingly difficult to trace the source of infection.

The prayer by the industry for a low cost technology for decontamination of thermally sensitive foods seems to have been answered by the development of a technique using low wattage electricity in the US. Though it may take some time before commercial equipment become available for decontamination of foods, the promise it holds for the future of food industry may be exciting. Excellent results have been reported with tomatoes which after packing in sealed plastic bags were exposed to a plasma field created by two high voltage, low wattage electric coils on either side. Generation of Ozone from the oxygen present with in the bag kills the pathogens within a matter of few seconds. After the treatment ozone does not stay to cause any oxidative damage to the contents and decomposes to the original atomic oxygen. Besides tomatoes, this treatment was found to be effective for spinach also and may work for any food material. The low electricity consumption of 30-40 watts, practically no rise in temperature in side the bag, no electrode intrusion into the container and suitability of both flexible and rigid plastic containers, make this technique attractive to processors as well as the consumers.

Before this technique is adopted some questions regarding use of ozone in food system need to be addressed. Generally ozone is considered a pollutant when it is present at the ground level and it is known to cause head aches, burning eyes and irritation in the respiratory passage at levels as low as 100 ppb. How much residue will remain in the treated produce must be assessed after processing. A concentration of 300 ppb is necessary to get a 99.99% kill of food borne pathogens. Also of importance is the susceptibility of the packaging material to ozone action and possibility of chemicals and artifacts generated that can contaminate the contents during processing. A claim that ozone can decontaminate fruits ad vegetables with respect to pesticide residues also calls for further study. Optimum time of processing for total kill, influence of moisture in the product on the efficacy of the process, effect of varying sizes and shapes of the materials to be treated on the product quality, etc will have to be worked out for different products.

It is likely that the above process, if technically found feasible, will be eventually patented and cost of acquiring it may be exorbitant. In the mean time why not Indian food scientists work on this principle and come out with a successful low cost gadget that will benefit thousands of small scale processors in extending the shelf life of many fresh as well as processed products in the country. Such innovations only can drive Indian food industry up the growth chart on a sustained basis.

V.H.POTTY
http://vhpotty.blogspot.com/