Effects of UV On Grocery Produce

Outside The Visible Spectrum:  How UV Radiation In Lighting Spoils Grocery Profits

Most grocery stores seek to create an environment of quality, abundance, and freshness.  Maintaining quality and abundance often depend on store hygiene, the supplying farms, and how high each clerk can stack a pyramid of apples.

But there is an enemy to freshness that most grocery store owners cannot see.  Or rather, they could not see without it.

Lighting can draw your gaze, evoke emotions, and guide your movement.  Yet while these commonly recognized features of illumination are mostly intangible, lighting can also have a significant impact on our physical world.  Let’s move beyond our visible spectrum and into the ultraviolet. Ultraviolet (UV) light helps plants and animals to grow in life, and it also accelerates their decay in death.  Exposure to some kinds of light during storage, packaging and processing can measurably degrade the quality of food.  Much coordination goes into minimizing the amount of sunlight that hits perishable goods after harvest, but more often than not these fresh consumables are put on display beneath a light that contributes to its spoilage.

Perishable foods like meat and produce are most often associated with freshness.  They are minimally processed, and therefore subject to a natural decay over time.  The expiration period can be delayed by technologies such as refrigerated trucks, growth inhibiting hormones, and produce misting systems.

Yet despite these efforts, meat spoilage alone is estimated to cost U.S. grocery store owners over $1 billion in lost revenue annually.

It is therefore critical for grocery store owners and operators to understand how lighting affects perishable goods and which technologies are available to extend shelf life.

Degradation from lighting most acutely affects foods with higher quantities of light sensitive elements like vitamins, pigments, amino acids, and fats.  Light-induced changes can directly damage a component of the food product, or pit two ingredients against each other.  The shelf life of these foods depends on many things, including temperature of the light, length of exposure and system implemented.
Sunlight has traditionally been the biggest enemy of food preservation.  If a farmer displayed produce and meat in broad daylight, it would not stay fresh for long.  Nowadays, we seldom see skylights in grocery stores because the high UV exposure from the sun would increase the rate of decay of fresh foods on display.

Traditional, man-made lights like halogen, high intensity discharge (HID) and compact fluorescent (CFL) also emit harmful UV, though to a lesser extent than the sun.  Fluorescent lamps, for example, pass UV rays through phosphors in order to produce visible light.
Although small doses of UV has been known to help kill certain kinds of bacteria and assist in the pasteurization of food, consistent exposure to UV will increase the decay rate of perishable goods.

A 2012 study by Stony Brook University determined most CFL bulbs have flaws that allow ultra violet (UV) radiation to leak at damaging levels.

Further, merchandisers have recently shifted towards more translucent packaging in an effort to showcase their goods.  While this benefits customers by allowing them to inspect food quality, it further exposes perishables to photodegradation from the grocery store lights.
In the event that a fluorescent light breaks, the mercury contained within the lamp requires hazardous waste removal procedures to be in place.  A simple broken fluorescent bulb contaminates all the foods beneath the lamp, and forces an aisle to be shut down until properly cleaned.
Spoiled food waste, aisle shut downs, and HAZMAT cleanups all represent significant financial challenges for grocery store owners and operators.  But new lighting technology presents a solution to these problems.

Upgrading to an LED lighting system reduces energy consumption by 40-90%, eliminates HAZMAT requirements, and (most importantly) extends the shelf life of perishable goods.

Beyond the energy efficient characteristics, light emitting diode (LED) technology does not expose food to the damaging levels of UV light found in traditional lamps.  Due to the low photochemical activity, LEDs emit an incredibly small amount of UV light.
The ability of LEDs to operate in cold temperatures without incident has made them an attractive solution for cooler displays and walk-in cold storage units.  Chains like Walmart and Target recognized early that LEDs were the best solution for their refrigerated displays.
If the food is not handled at a consistent temperature, it can spoil.  Damaging microorganisms can begin to flourish if certain temperatures are not maintained.  An 18-degree difference can double the rate at which food can become tainted.

The reduced heat output of LED lighting further aids in spoilage prevention.

LEDs now come in a wide variety of high-CRI, natural light color temperatures as well, to help grocery owners maintain a warm ambiance.  The warmth of light is measured in two ways: Correlated Color Temperature (CCT) measures a lamp’s color when lit, and Color Rendering Index (CRI) which accounts for how the light reflects colors.  Both CCT and CRI are measured in degrees Kelvin (K).  

Most lighting professionals will recommend “neutral white light” (3000K – 4500K) for grocery applications, because it enhances most colors equally.  LED technology has advanced to the point where it can replicate the color of natural sunlight.

Further, employees often love the transition away from fluorescents and HIDs, as these old lamps are most commonly associated with flickering and color inconsistencies (Lighting Productivity).  Aside from benefiting store employees, fewer headaches and reduced eyestrain will also encourage customers to linger.

Switching to LEDs

The influx of new LED technologies to the market has made choosing the right system a daunting task.  The lighting environmental consultants at Focus Earth have developed a robust system of measurements that compare products to help customers navigate the LED and controls market.
The energy efficiency of LED technology typically produces an ROI of 3-5 years.  In grocery and food applications, that ROI can be further shortened by factoring in food spoilage reduction from UV abatement.  Government and private financing plans are also available that make owners cash flow positive from the date of installation.

Since LED technology is smart system compatible, they can be adjusted in both color and intensity.  This means that grocery store marketers can change their lighting settings to most appropriately complement the rotating products displayed beneath.
On a practical note, LED maintenance is far less than traditional fluorescent tubing.  A typical fluorescent needs to be replaced about every six months.  LEDs are most commonly rated between 50,000 and 100,000 hours, (5 to 11 years if run non-stop).  This extended life cycle helps to save on labor and replacement costs for owners.

The right lighting environment can help create an atmosphere that supports buying aesthetics, and LED technology can help products stay fresh for longer.

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