Aloe vera gel as a Novel Edible Coating for Fresh Fruits: A Review

Aloe vera gel as a Novel Edible Coating for Fresh Fruits: A Review

Jawadul Misir1,Fatema H. Brishti1M. M. Hoque1

1Department of Food Engineering and Tea Technology, Shahjalal University of Science and Technology. Sylhet, Bangladesh

American Journal of Food Science and Technology, 2014 2 (3), pp 93-97. 
DOI: 10.12691/ajfst-2-3-3

1. Introduction

Consumers around the world demand for food of high-quality, without chemical preservatives, and an extended shelf life. Therefore, an increased effort has been made to develop new natural preservatives and antimicrobials. Many storage techniques have been developed to extend the marketing distances and holding periods for commodities after harvest. Different preservation methodologies have been developed. One method of extending post harvest shelf life is the use of the edible coatings. Edible films and coatings have received considerable attention in recent years because of their advantages including use as edible packaging materials over synthetic films. 

Edible coatings are thin layers of edible material applied to the product surface in addition to or as a replacement for natural protective waxy coatings and provide a barrier to moisture, oxygen and solute movement for the food. They are applied directly on the food surface by dipping, spraying or brushing. Edible coatings are used to create a modified atmosphere and to reduce weight loss during transport and storage. In fact, the barrier characteristics of gas exchange for films and coatings are the subjects of much recent interest.

Aloe vera is a well-known plant for its marvelous medicinal properties. It is a tropical and subtropical plant. Recently, researchers from Spain have developed a gel based on Aloe vera that prolongs the conservation of fresh fruits. This gel is tasteless, colorless and odorless. This natural product is a safe and environmentally friendly alternative to synthetic preservatives such as sulfur dioxide. According to the researchers, this gel operates through a combination of mechanics, forming a protective layer against the oxygen and moisture of the air and inhibiting the action of micro-organisms that cause food borne illnesses through its various antibacterial and antifungal compounds. Aloe vera gel-based edible coatings have been shown to prevent loss of moisture and firmness, control respiratory rate and maturation development, delay oxidative browning and reduce microorganism proliferation in fruits such as table grapes, sweet cherries and nectarines. The main goal of this article is to critique and update the information available on Aloe vera gel properties, its preparation and on the use of Aloe vera gel coatings as an effective preservative to improve the safety, quality and functionality of fresh fruits.

2. Aloe Vera 

The word Aloe derived from the word Arabic “Alloeh” or the Hebrew “Halal” meaning “bitter, shinny substance”. Aloe vera is known as “plant of immortality” by the Egyptians due to its beneficial effect on human health. It is generally presumed that the origin is Arabia, Somalia, Sudan, and Oman. At present, Aloe vera is widely distributed throughout the tropics and subtropics. Aloe vera is a perennial plant. It’s thick, thorn- edged leaves, ranging in color from gray to bright green, give aloe vera the appearance of a cactus, but, it is, in fact, a member of the lily family (Liliaceae). A typical Aloe vera plant produces two or three yellow tubular flowers, shaped much like those of the Easter Lily, and it flowers intermittently throughout the year. It’s thick leaves contain the water supply of the plant to survive long periods of drought. The leaves have a high capacity of retaining water also in very warm dry climates and therefore this plant can survive very harsh circumstances where most other vegetation disappears.

There are two distinct layers of Aloe vera leaves which are clearly visible in transverse section: the green outer leaf rind and the soft, colorless, inner gel parenchyma. Aloe vera is an unique plant which is a rich source of many chemical compounds. Prof. Tom D. Rowe was probably first to take vital steps in the chemical analysis of the plant. Aloe vera now reported to contain as many as 75 nutrients and 200 active compounds including sugar, anthraquinones, saponins, vitamins, enzymes, minerals, lignin, salicylic acid and amino acids. In today’s society many people have food allergies or personal preferences that would prevent them from ingesting these items. Therefore, Aloe vera is a great dietary source to meet those amino acids needs. 

3. Constituents of Aloe Vera Gel....