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Novel, Edible Films and Coatings for Fresh Processed Fruits and Vegetables

In the 246th National Meeting & Exposition of the American Chemistry Society (ACS)—the world’s largest scientific society, Scientists discussed about a topic that is closely related to our daily life—research on edible coatings for fruits and vegetables. It becomes very popular in modern food processing industry to use invisible, colorless, odorless and tasteless coatings to keep foods fresh. However, people still don’t know how to maintain the tastes, flavors and nutritional values for foods that are easy to change color and deteriorate.

Fruits and vegetables have peel, which can form natural barrier, preventing fruits and vegetables from drying, color changing and other forms of deterioration. Attila E. Pavlath said, “Nature is the best chemist, and also the best teacher. We can learn from nature to improve edible coatings and preserve foods’ quality and nutritional value.”

Pavlath and his group developed a novel technology that allowed sliced, packaged apple to be stored in refrigerator for 2 – 3 weeks without turning brown or losing crispness. Generally speaking, Pavlath’s method involves treating freshly cut apple slices using a form of Vitamin C so that the desirable characteristics of fresh apples are successful retained without leaving a detectable residue.

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The edible coatings consist of a thin layer of edible material applied to the surface of a food product so that its freshness can be preserved. For an instance, apple lose some of their natural wax coating during the harvest washing process. The edible coating, which is used to replace the natural wax coating, is a thin layer of carnauba wax, obtained from palm tree leaves. This kind of wax also provides an appealing gloss for sugar-coated chocolate candy. Some other commonly seen edible coatings include alginate, starch, carrageenan, gluten, whey and beeswax. *Image source: shutterstock.

Pavlath explained in more details, “The thing applied to treat apple slices is calcium ascorbate, a calcium salt of Vitamin C. This is a relatively easier process, but it took us five years of research starting from whey proteins, carbohydrates and fats—we are devoted ourselves in developing the best coating.”

Pavlath pointed out that edible films are not a 21st century innovation. They can date back to at least as early as the 1100s, when merchants in citrus-growing regions in southern China applied wax for preserving oranges shipped by caravan to the Emperor’s table in northern China. For centuries, European people preserved fresh fruits with “larding”, a coating came from the melted fat from hogs. These food coatings were good at sealing off the fruits, preventing the exchange of gases with the air. However, today’s edible films allow gas exchange and also have other features that can keep freshness, aroma, flavor, texture and nutritional value. Pavlath said that they generally provide the same protection against bacteria just as their natural skin if foods are treated under sterile conditions when they are cut in factories. Workers spray the edible films on foods or they immerse the foods in the liquid coating after cutting. The finished vegetables and fruits will be stored in sealed containers for sale.

Pavlath also shared some points on Arctic Apple, a genetically modified, precisely breed apple that contains non-browning character. Pavlath noted:” Nowadays, GM engineering has different application. For the past five decades, some unideal characters have also introduced in the process.  I don’t know how Artic Apple tastes. Our approach can be applied to various breeds of apples with different tastes. In order to eliminate browning genes, individual research needs to be done on different breeds.”

 So, what is the great 21st century challenges in edible coating research and development? Pavlath cited two challenges: one is finding an edible coating that can make fresh-cut sliced bananas, American’s favorite fruit; the other one is developing a coating for avocados, which are also notorious for quick discoloring after peeling.

SourceEurekAlert!
Image sourceShutterstock

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