Emergence of LED based bacterial destruction technology- Opening up a new avenue for safeguarding foods

Technology for food preservation has evolved over a hundred years in the past and from the early findings that salt, sugar, acids can protect foods from deterioration by pathogenic microorganisms, modern food technology has been able to innovate newer processes with more reliability and assurance. Canning was considered the most trustworthy process and during various wars canned foods formed the backbone of the fighting soldiers. Emergence of technologies like irradiation, High pressure processing, controlled environment storage/packing, HTST etc are now available to the industry for different types of products. Ultimately the effectiveness and acceptability of a technology depend on its ability to preserve the quality of the food processed, achieving cent percent kill of microbes and the cost of using the technology under commercial conditions. Recent claims that blue LED rays can be an effective tool in the hands of technologists to preserve foods, offer a new option that may be acceptable to the industry. Here are more details of the same as reported recently.

"Blue LEDs in conjunction with cold temperature and acidic conditions can kill off foodborne pathogens making chemical-free preservation a possibility for a range of foods. Fresh-cut fruits and ready-to-eat meats are just some of the foods which are mildly acidic (pH 4.5) that could use this preservation technology to avoid the use of chemical preservatives and present the 'clean label' that consumers desire. A team of scientists from the National University of Singapore (NUS) has found that blue light emitting diodes (LEDs) have strong antibacterial effect on major foodborne pathogens and are most effective when in cold temperatures (between 4 and 15°C) and mildly acidic conditions of around pH 4.5. These findings were recently published in the Food Microbiology journal in June 2015. While LEDs are most commonly known as an energy-saving light source, they have also been known to have an antibacterial effect. Bacterial cells contain light-sensitive compounds that adsorb light in the visible region of the electromagnetic spectrum (400-430 nm), which is mainly blue LED light. Exposure to illumination from blue LED light can hence start off a process within the cells that ultimately causes the cells to die. Existing studies on the antibacterial effect of LED illumination mostly evaluated its efficacy by adding photo sensitisers to the food samples, or by using very close distance of less than 2 cm between the bacterial suspension and LED light source. These conditions would not be viable for application on food preservation. The NUS team, led by Assistant Professor Yuk Hyun-Gyun, from the Food Science and Technology Programme at the NUS Faculty of Science, is the first so far to show that factors such as temperature and pH levels, which are typically related to food products, can affect the antibacterial effect of LEDs.
In this study, the team placed three major foodborne pathogens — Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Typhimurium — under blue LED illumination and varied the pH conditions from acidic to alkaline. The team found that higher bacterial inactivation was achieved at acidic and alkaline pH conditions than when neutral. In particular, acidic conditions were more detrimental than alkaline conditions for L. monocytogenes. For E. coli O157:H7 and S. Typhimurium, alkaline conditions were most detrimental although acidic conditions were also sufficiently effective in deactivating them. A previous study in 2013 by the same team had also looked at the effect of temperature on blue LED's ability to deactivate bacterial cells and found the antibacterial effect to be most enhanced in chilling temperatures. Asst Prof Yuk said, "Taken together, our two studies point to a potential for preserving acidic foods in combination with chilling temperatures without chemical treatments. This could meet the increasing demand for natural or minimally processed foods without relying on chemicals such as acidulants and artificial preservatives to preserve food products."

Though blue light rays are used widely for a variety of applications, its utility to food preservation is some what new deserving further development to bring it to wide scale use commercially. The major constraint has been that photo sensitizers are required to activate the kill effect of the blue rays. Also the efficiency of blue rays depends largely on the distance between the food sample and the source of the light. Though cold temperature and pH conditions can enhance the kill effect, how suitable equipment can be designed for large scale commercial application needs to be addressed. If these problems are overcome, blue ray technology may find wide applications in future in the industry, retail stores and domestic refrigerators, especially to protect cut fruits and vegetables, meat cuts and other perishable foods

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

FOOD IRRADIATION- TECHNOLOGY-INCREASED EFFICENCY

If there is ever a clean food preservation technology available to mankind, irradiation process eminently qualifies for that spot. Though many countries have approved irradiation as a safe process to kill bacteria and other pathogenic microorganisms that spoil food, its wide scale use at the industry level is constrained by many practical problems. As many a consumer identifies irradiation as related to the destructive and deadly "Hiroshima" bombs which killed and maimed thousands of people, there is an understandable reluctance to "accept" foods undergoing irradiation process. All governments are moving cautiously in this area and irradiation is slowly being used in some selected cases with large benefits flowing from it. It is against this background that new approaches are being tried out to reduce radiation doses as much as possible to allay the misplaced fears of some consumers. The recently reported use of modified atmosphere packing (MAP) in combination with irradiation seems to be achieving this purpose.

"A new research has developed a method, which could significantly reduce the amount of irradiation needed to kill 99.99 percent of Salmonella, E.coli and other pathogens on fresh produce. A team of Texas AgriLife Research engineers found that by packing produce in a Mylar bag filled with pure oxygen and her colleagues found they could almost half the amount of radiation needed to kill those pathogens. Reducing the amount of radiation is not so much a safety measure as it is a way to preserve quality of the produce, said Carmen Gomes, AgriLife research food safety engineer. The U.S. Food and Drug Administration recently approved the use of irradiation at dosages of up to 4,000 Gray on leafy greens such as spinach, Gomes said. A Gray is a measure of ionizing radiation dose and it is equal to the absorption of 1 Joule of ionizing radiation by 1 kilogram of matter. "That dosage was determined as what was necessary to achieve an 100,000-fold reduction of such pathogens as E. coli O157:H7 and salmonella. However, we know based on previous research conducted by our group that above 1 kilo Gray (1,000 Gray) the quality of leafy vegetables starts to decay and they lose their freshness," noted Gomes. A 100,000-fold reduction corresponds to a 99.999 percent kill rate, according to Dr. Rosana Moreira, another member of the team".

Though the scientists claim that reducing the dosage serves a more useful purpose, viz. preserving the textural quality of crops like fresh greens, it is note worthy that a 50% lower dosage is able to achieve the same result when MAP is used before subjecting to irradiation process. Probably it is time for organizations like FAO, WHO and others to promote irradiation technology as the most important technique to prevent or reduce the massive food losses on a significant scale in the coming years. The logistics involved in making available low cost irradiation equipment must be addressed on priority so that majority of the industry can afford to establish the required facilities at minimum investment.

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

CO2 HELPING "GREENING" CAUSE-NEW FREEZING TECHNOLOGY

With halogenated hydrocarbons progressively being phased out by the refrigeration industry
due to their ozone depleting property, CO2 has become the most agreeable refrigerant available
to day. Though CO2 itself is being blamed as a green house gas, it has several useful role in
to day's industrial world. It plays a critical role in food preservation, especially fresh produce
through modified atmosphere storage technology. Dry ice, a by-product from alcohol industry
is frozen CO2, achieved through compression but finds little use due to inconvenience inherent
in its handling. Latest development of freezers based on CO2 will go a long way in addressing
the exacting need of the refrigeration industry. 

"The system is Food Lion's first "cascading" CO2( )refrigeration cycle, which uses a single system and  just
one condensing unit to refrigerate and freeze foods. Before Kysor//Warren developed this system, grocers
incorporating CO2 refrigeration systems needed two condensing units as well as a freezer-specific system
and a refrigeration (medium temperature) specific system.  This is Kysor//Warren's first CO2( )advanced
refrigeration system in a  retail grocery store setting".

The CO2 based cooling system, if proved to be as per the expectations of the food industry
may make an immediate impact in many developed countries where cold chain and cold storage
systems are well established and are an integral part of the retail net work. How far this is
relevant to countries like India with practically no worthwhile refrigeration infrastructure existing,
as of now, is to be seen.  

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