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

MARINE ECO-SYSTEM-IMPACT OF CO2 EMISSION

CO2 emission due to human activity, especially fossil fuel burning, is supposed to cause global warming and consequent damage to the ecosystem and human life. Now comes the report that the oceans act like a vast sink for CO2 absorption as more than two thirds of earth's surface is covered by water and the acidity of the oceans is increasing perceptibly due to dissolved CO2. According to eco scientists, such a change can bring about unprecedented changes in the marine life with catastrophic consequences.

"The level of acid in the oceans is increasing at an unprecedented rate and threatening to change marine ecosystems, says a new study by the US National Research Council. It says the oceans are absorbing more than 1 million tonnes of carbon dioxide an hour - one-third of today's carbon dioxide emissions - and are 30 per cent more acidic than before the Industrial Revolution started roughly 200 years ago. Unless emissions are reduced, ocean acidity could increase by 200 per cent by the end of the century and even more in the next century, said James Barry, a senior scientist at the Monterey Bay Aquarium Research Institute in California and one of the study's authors".

It is amazing how a mere drop in pH from 8.2 to 8.1 in two hundred years could have such serious repercussions on the marine eco system affecting practically every species that is sheltered by the sea. What is more alarming is the prediction that the pH drop can be steeper during the present century unless CO2 emission is brought under control through inter country cooperation and renewed resolve.

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