Water and Freezing in Food

Abstract

As an overwhelmingly major component, the role of water in food is reviewed comprehensively from a physicochemical view point. In aqueous solutions, the deviation of water activity, a w , from the ideal solution was proved to arise mainly from solute hydration. In macromolecule solutions, interactions among macromolecules were affected by a w and also the balance between the hydration and cosolute-binding of macromolecules. The ice fraction, which affects various properties of frozen food, was described well by a two-parameter equation with the initial freezing temperature and the unfrozen water content. In crystallization, ice crystal growth is extensively driven by heat transfer, causing unstable dendritic growth that is limited by water diffusion. Methods for freeze concentration were classified into four categories, and equilibrium suspension crystallization and progressive freeze-concentration were compared as possible alternatives in practice. Some chemical reactions are accelerated in the frozen state. This mechanism was explained by the concentration effect with freezing. In the freezing of cells, the freeze-induced dehydration rates of plant cells were much lower than those of microorganisms and animal cells, which seemed to explain the lower freeze-tolerance of plant cells and tissues.

Recent research on factors influencing the quality of frozen seafood

“…Foods with a high lipid content exhibit less expansion during freezing, as lipids contract when solidifying at low temperatures (Okazaki 2009). The freezing point of food (the temperature at which ice crystals begin to form) and the final temperature after freezing influence the amount of unfreezable water, affecting the quality degradation reaction (Tolstorebrov et al 2016;Miyawaki 2018). These temperatures differ among fish species.…”

Concentration of Aqueous Residue from Isada Krill Using Freezing-Thawing Technique

“…Methods for concentrating liquid solution are classified into three categories: evaporation, reverse osmosis, and freeze concentration [9]. Evaporation is a simple method that removes water by heating, but it may cause quality degradation [10].…”

“…Although the method can be operated without heating, there are concerns about microbial contamination and difficulty in maintaining membrane performance [10]. Freeze concentration causes the least quality deterioration among the three methods [9], and it can suppress microbial [9]. Among these methods, freezing-thawing is the simplest one [9].…”

“…Freeze concentration causes the least quality deterioration among the three methods [9], and it can suppress microbial [9]. Among these methods, freezing-thawing is the simplest one [9]. In the freezing-thawing method, the liquid sample is completely frozen and then gradually thawed [12].…”

“…In the freezing-thawing method, the liquid sample is completely frozen and then gradually thawed [12]. A solution with a higher solute concentration than the original solution is obtained in the early stages of melting [9]. The application of this method to the concentration of low-value-added solutions such as food waste has been studied in past [13].…”