³ÉÈËÊÓƵ

Researchers in South Dakota State University's Department of Dairy and Food Science are improving the shelf life of strawberries and raspberries using biodegradable packaging material. 

Raspberries and strawberries are two universally loved fruits that share a common problem: they don't last long. Following their harvest, both fruits will go "bad" much quicker than other popular fruits, such as apples and bananas.

Being highly perishable, these fruits have a . By the time they get to the grocery store, they only have a few short days of freshness on the shelves. According to past research, around 25% of strawberries are discarded at the distribution and retail level, resulting in economic losses.

Researchers from South Dakota State University's Department of Dairy and Food Science are working on a solution. They believe that by developing biodegradable packaging material from agriculture residue — the researchers refer to these materials as "films" — they can extend the shelf life of raspberries and strawberries.

Can innovative packaging materials help extend shelf life? 
Srinivas Janaswamy is an associate professor at South Dakota State University's Department of Dairy and Food Science. Along with graduate students Sandeep Paudel, Sumi Regmi and others, Janaswamy has been developing plastic-like films from various biosources to help curb the plastic waste crisis. Most importantly, Janaswamy's films biodegrade in the environment in less than 60 days — much shorter than traditional plastic, which takes nearly 700 years to degrade.

"Plastic is a popular choice for packaging due to its portable, durable and lightweight traits," Janaswamy said. "However, its intrinsic ability to remain dormant for several centuries and the human inability to destabilize and destroy its structure results in the piling of perilous plastic debris."

Janaswamy has been exploring different ways his films could be utilized. One of the more innovative ways is to use them as packaging material to extend the shelf life of perishable fruits. Over the course of three separate studies, Janaswamy, Paudel and Regmi demonstrated how films developed from the residue of , and — all byproducts of agricultural crops — can extend the shelf life of these perishable fruits.

"The potential of cellulosic residue from soybean hull and alfalfa has been demonstrated to develop biodegradable films and extend the shelf life of raspberries and strawberries," Janaswamy said. 

Traditionally, — a material similar to Styrofoam — has been used in food packaging, specifically during the storage and transit of fresh fruit. For these studies, Janaswamy, Paudel and Regmi compared how long the fruits would stay fresh with a polystyrene film and with a film developed from different agricultural byproducts.

For the raspberry experiment, the researchers utilized

"Our film extends the shelf life of raspberries by six or more days compared to polystyrene film," Janaswamy said. "The soyhull films are also advantageous in minimizing plastic-related issues."

The researchers make the films by extracting from the byproduct, whether that be alfalfa or soybeans. The extracted cellulose then undergoes bleaching, distilling and treatment before being prepared into a film.

Generally, the films look and feel the same — transparent — but have slightly different properties depending on the source material. For example, the alfalfa-derived films show slightly better tensile strength than soybean hull-derived films.

The team took a similar approach in their strawberry experiment. Rather than corncob, the researchers extracted cellulose from alfalfa. These films extended the shelf life of strawberries two days longer than standard polystyrene plastic films.

Janaswamy partly credits the UV radiation-blocking properties of the films for being able to extend the shelf life of the fruits, and better control the transfer of moisture and gases. Janaswamy describes them as "breathable" filters that create a modified atmosphere inside the container. This process better controls water loss from the fruits, which allows them to maintain freshness for longer.

There are many potential benefits to this research. Economic losses for producers could be minimized, and consumers could have fresh fruit "keep" longer in their refrigerators. Because these films are also biodegradable in a relatively short amount of time, they could help reduce the amount of plastic waste littered in the greater environment. They could also be a new source of income for agricultural producers and allied industries.

"Overall, this research opens a window of opportunities with the combined efforts of material science, food technology and environmental science toward improving sustainable food packaging," Janaswamy added.

Funding for this research was provided by the , , , and the .