Food preservation is critical for keeping the global food supply safe and available for consumers. Food scientists study production and processing to develop new technologies that improve the quality and quantity of healthy food products.
The main goal of food technology is to safely increase yields with effective quality control and to preserve the environment and fulfill consumer expectations. Both consumers and food producers require more research about fresh-cut produce.
Producers demand inexpensive and effective technologies to safely preserve the quality of the products. In the same manner, consumers want quality low priced fresh-cut produce. Food scientists attempt to solve problems in freshcut
processing and quality preservation.
In the past two decades, rapid advances in scientific knowledge on fresh-cut produce preservation have been developed. The present article reviews technologies such as ultraviolet irradiation (UV-C), edible coatings, active packaging and volatiles, noting the areas in which information is still lacking and commenting on future trends.
Ultraviolet light for food preservation
The Ultraviolet light UV is a type of non-ionizing radiation with wavelengths from 100 to 400 nm, which is usually classified in three types: UV-A (315–400 nm), UV-B (280–315 nm) and UV-C (100–280 nm).
Ultraviolet C irradiation
UV-C (ultraviolet C) irradiation has its maximum at 254 nm and is, of the three, the one with the highest germicidal action, and therefore, the most studied. Radiation has been used both to delay ripening associated processes and to reduce microorganism growth.
There are several publications on this study, and recently, UV-C is using as an alternative treatment to preserve the quality of different fruits and vegetables.
Pre-storage applications of UV-C reduced chilling injury in pepper, delayed senescence yellowing, chlorophyll degradation, and pheophytin accumulation in broccoli, controlled storage rot in strawberry, reduced pathogen growth and induced disease resistance in the fruit tissue.
UV-C treatments induced a stress that simulates the production of phenylalanine ammonia-lyase (PAL), an enzyme that plays a key role in the synthesis of phytoalexins, phenolic compounds that improve the resistance of fruits and vegetables to microorganisms. The UV-C treatment-induced phytoalexins have been identified in fresh-cut cantaloupe and fresh-cut pineapple.
Exposure to UV-C delays fruit softening, one of the main factors determining fruit postharvest life. Scientists found that UV-C decreased the activity of enzymes involved in tomato cell wall degradation and delayed fruit softening.
Reports also shows the reduction of strawberry fruit decay by UV-C application. Chilling injury symptoms and deterioration of “Tommy Atkins” mangoes was also reducing by UV-C irradiation during storage at 5°C .
In addition, UV-C irradiation reduced ethylene of apple slices and had minimal effect on the respiratory physiology of tissues. Scientists studied the effect of short UV-C doses (0.4 – 8.14 kJ/m2) on the shelf-life of the fresh processed lettuce. And found that the use of these short doses is effective in delaying senescence and deterioration in fresh-processed lettuce. Thereby maintain the quality of the product.
Edible coating has been used in a wide range of food products. It may be applied directly on the food surface by dipping, spraying or brushing, in addition to, or as a replacement for natural protective waxy coatings. It prevent water loss and gas exchange and provide a micro-modified atmosphere around products that retards food deterioration.
Due to their natural biocide activity or as a consequence of the incorporation of antimicrobial compounds, edible coatings also enhance food safety. It also plays a role as a physical method to improve quality and extend shelf-life of fresh-cut fruits and vegetables.
There are several reports discussing edible coating uses. Scientists studying various edible coatings made from apple puree with different concentration of fatty acids, fatty alcohols, beeswax and vegetables. Resultantly, they found that edible coatings control browning of fresh-cut apple for 3 days at 5°C.
It is important to mention that sensory evaluation confirmed that chitosan-coated longan fruit, and peaches had better quality compared to controls. The scientists are also observing a direct correlation between coating concentration and fruit quality.