Fruits and vegetables are agricultural commodities that are widely consumed by people around the world due to their many health benefits. Fruits and vegetables have a higher nutrient content, including vitamins, minerals, dietary fiber, organic acids, and antioxidants and others. However, most fruits contain high water content so that they are classified as perishable food, as well as vegetables that are easily wilted. On this basis, there is a need for the availability of effective preservation techniques for fruits and vegetables.
1. Fast freezing
Quick freezing has been considered as one of the most important preservation technologies available for the preservation of fruits and vegetables. So preservation technologies need to be further developed by great researchers Therefore, the aim of this review is to present an overview of recent advances in blanching and freezing technologies of fruits and vegetables.
2. Food Preservation
When preserving food, we need to pay attention to the quality of the fruits and vegetables that have been frozen. It is useful to choose a technique that suits the purpose of preservation. One preservation technique suitable for fruits and vegetables is quick freezing. Quick freezing lowers the temperature of fruits and vegetables to freezing point in a very short time and hardly changes their nutritional quality and sensory characteristics.
The prevailing low temperature effectively reduces microbial and enzyme activity and attenuates oxidation and respiration of harvested fruits and vegetables. Due to increasing urbanization, the consumption of frozen fruits and vegetables is increasing mainly due to convenience, time saving and other practical reasons. Blanching is one of the pre-treatment methods in quick freezing and is included as a factor affecting the quality of fruits and vegetables including raw material characteristics, pretreatment technology used before freezing, quick freeze technology and post-freezing process.
However, conventional blasing applications are inappropriate and lead to loss of texture, soluble nutrients, pigments and aroma. In addition, improper freezing methods will lead to the formation of large ice crystals that damage the cell structure of the cell walls of fresh fruits and vegetables. The combined effect of using inappropriate or inefficient blanching and freezing protocols leads to irreversible and undesirable changes in the quality attributes of the final frozen product. Therefore, the application of new blanching and freezing technologies is essential to minimize the loss of quality in frozen foods.
Research on blanching has been continuously developed and attracted a number of researchers. Such as the research conducted by Wang et al. (2007) When blanched samples are then frozen quickly, they produce smaller ice crystals that reduce damage to the microstructure of vegetables (Wang et al. 2007). One of the innovations in blanching methods is OH (Ohmic blaching) technology which has tremendous potential in blanching applications.
When applied to blanching, OH provides rapid and uniform heating, which causes less thermal damage to the treated food compared to conventional limited heat transfer methods. Other advantages, compared to conventional blanching, include better color retention, better preservation of heat-sensitive compounds, shorter processing times, and higher yields.
After we get to know innovative blancing methods such as OH, we will also discuss freezing technologies such as de-hydrofreezing. Dehydrofreezing is one of the newly developed food freezing techniques where fresh or minimally processed food can be produced. In this process, food is partially dehydrated before freezing by removing some of the water in it thereby lowering the amount of crystals formed during the freezing process. Thus, tissue damage can be reduced during freezing.
In addition, the freezing time of samples that have been dehydrated is substantially shortened as their water content is reduced. As in the study conducted by Ramallo and Mascheroni (2010) who stated that osmotic dehydration and hot weather drying had a favorable effect in reducing the time required to freeze pineapple samples.
The freeze-thaw process affects the mechanical property values of pineapple samples. After reading this review, we have become more familiar with renewable preservation technologies compared to the conventional freezing techniques that we are familiar with. TA