Abstract
To reduce energy expenditure, dehydration processes are being improving by pretreatments and changing frozen stage. Alkaline emulsion pretreatment was introduced to freeze-drying method to reduce the drying time of grapes and obtain significant energy savings. Dehydration process for untreated fresh grape samples was 22 hours, using industrial freeze-drying equipment. It was obtained a high quality product with range 3 % to 7% of final humidity, without losing natural characteristics and organoleptic properties of the grapes. it was found by modifying standard equipment frozen method, using dry ice (CO2) and applied coconut oil alkaline emulsion pretreatment, a 54% energy saving. Even more the dehydration process decreased the microbial load in the fruit. A product with low number of microorganisms may be consumed by patients with low defenses as cereals, nutritional bars, salads, yogurts, etc. Finally, if all enterprises involved in this field take into account these findings and improve constantly their process they will stop emitting several kg of CO2 into the atmosphere.
Highlights
Nowadays, to preserve freshness and nutritional quality on fruits and vegetables are applied several methods, due to a different perishable factors as fungi, yeasts, bacteria and enzymes (De Torres et al 2015)
Fresh grape was obtained in the local market. 5.4 kg of whole grapes were used in the experiment
The humidity achieved for rehydrated samples was 75% as compared with initial humidity of fresh grapes
Summary
To preserve freshness and nutritional quality on fruits and vegetables are applied several methods, due to a different perishable factors as fungi, yeasts, bacteria and enzymes (De Torres et al 2015). When it is exposed to open air and high temperatures, the decomposition process is accelerated, having a relatively short life. When this product is decaying, it is harmful to health and useless. Most storage techniques require low temperatures, making the product difficult to transport and store, and increasing energy expenditure. On the other hand, drying methods change the appearance and physical structure of products, giving advantage in transport, since it is extremely lightweight and covers less space than a fresh product to store and send, impacting positively, handling and large scale transport of product. There are several dehydration methods such as osmotic dehydration, vacuum, ultrasound, heat-pump, microwave, freezedrying, spry, and a combination thereof (CandiaMuñoz et al 2015, Fernandes et al 2011, James et al 2014, Sagar & Suresh Kumar 2010, Samoticha et al 2016, Souza et al 2014)
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