2.3.2 Washing
The
propensity of water to form solutions and emulsions is useful in
various washing processes. Many industrial processes rely on reactions
using chemicals dissolved in water, suspension of solids in water
slurries or using water to dissolve and extract substances. Washing is
also an important component of several aspects of personal body hygiene.
2.3.3 Food processing (Cooking)
Boiling,
steaming, and simmering are popular cooking methods that often require
immersing food in water or its gaseous state, steam. Water is also used
for dishwashing. Water also plays many critical roles within the field
of food science. It is important for a food scientist to understand the
roles that water plays within food processing to ensure the success of
their products.
Solutes such as salts and sugars found in water
affect the physical properties of water. The boiling and freezing points
of water are affected by solutes, as well as air pressure, which is in
turn is affected by altitude. Water boils at lower temperatures with the
lower air pressure that occurs at higher elevations. One mole of
sucrose (sugar) per kilogram of water raises the boiling point of water
by 0.51 °C (0.918 °F), and one mole of salt per kg raises the boiling
point by 1.02 °C (1.836 °F); similarly, increasing the number of
dissolved particles lowers water's freezing point (Vaclavik and
Christian, 2007).
Solutes in water also affect water activity that
affects many chemical reactions and the growth of microbes in food
(DeMan, 2009). Water activity can be described as a ratio of the vapor
pressure of water in a solution to the vapor pressure of pure water
(Vaclavik and Christian, 2007). Solutes in water lower water
activity—this is important to know because most bacterial growth ceases
at low levels of water activity (DeMan, 2009). Not only does microbial
growth affect the safety of food, but also the preservation and shelf
life of food.
Water hardness is also a critical factor in food
processing and may be altered or treated by using a chemical ion
exchange system. It can dramatically affect the quality of a product, as
well as playing a role in sanitation. Water hardness is classified
based on concentration of calcium carbonate the water contains. Water is
classified as soft if it contains less than 100 mg/l (UK) or less than
60 mg/l (USA).
According to a report published by the Water Footprint
organization in 2010, a single kilogram of beef requires 15 thousand
litres of water; however, the authors also make clear that this is a
global average and circumstantial factors determine the amount of water
used in beef production (Mekonnen and Hoekstra, 2010).
Microbial
risks associated with the water treatment processes at large water
plants, during distribution of treated drinking water to consumers or
activities undertaken by the end-user are not included here. These
factors play a significant role in the overall microbial safety of
drinking water, especially in communities with extensive piped water
supply systems. Under field and emergency conditions the main safety and
security efforts are focused on selection of the best raw water source
available, utilization and control of an effective treatment process and
control of security.
The significance of drinking water safety and
security has increased, especially after the terrorist acts in 2011
(Rose, 2012; Meinhardt, 2015). Although, these acts were not targeted
against drinking water supplies, the vulnerability of these supplies as
targets of bioterrorism has been a concern of public health authorities
and policymakers (Christen, 2011). The international concepts of hazard
analysis of critical control points (HACCP) (Dewettinck et al., 2011;
Howard, 2013; Westrell et al., 2014) and water safety plans (WSP) by the
World Health Organization (WHO) (World Health Organization, 2014) have
been introduced to enable the improvement of drinking water safety and
security. WSPs include health-based targets, which means that the
microbial risks and adverse health effects to which a population is
exposed through drinking water should be minimized, be very low and not
exceed the tolerable risk suggested by WHO (World Health Organization,
2014). Nationally both civil and military authorities and other
organizations have initiated projects to develop plans and measures for
ensuring safe drinking water supplies. The present studies will
hopefully aid in assessing the microbial safety of drinking water and in
developing practical plans to improve water safety, especially in the
field.
