Water in Biological and Food Systems

Abstract

This article presents data on the physicochemical characteristics of water in biological and food systems such as redox potential, water activity, water potential; and their influence on the processes occurring in plant materials and processed products. According to the laws of thermodynamics, water in biological and food systems is in a stationary state. Entropy changes in biological and food systems do not occur during reversible phase transitions of water. In all studied samples (E>0), despite the rather high content of antioxidants (polyphenols and L-ascorbic acid) in plant raw materials. The only exception was sweet pepper E= -10…+50 mV. The relatively high content of L-ascorbic acid, up to 102 mg.100 g^-1, led to a decrease in the redox potential and a shift in redox reactions towards an increase in the reduction potential of the system water – L-ascorbic acid (E ≤ 0). Bound water has anomalous properties, for example: its density increases, loses the properties of a solvent, fluidity is lost, the boiling point is above 100 °C. In such an environment, biochemical, chemical and biological processes proceed at a low rate, and at a_w≤ 0.2 these processes stop completely. Alkaline mineral water belongs to the hydrocarbon group of water obtained from natural sources. The acidity of water exceeds pH 7. Because of the predominance of bicarbonate ions (HCO₃-), sodium, potassium, magnesium and other minerals in it, the water is conditionally called alkaline, and its beneficial properties are used to treat several diseases. Water has unique properties associated to a certain extent with the polarity of its molecules and their ability to form hydrogen bonds with each other. Therefore, the electrical polarity of liquid water molecules has the property of forming many hydrogen bonds with a total strength between the molecules.