George J. Banwart

Regulations and Standards

When the United States began to change from a rural society to an urban one, food science was nonexistent, microbiology was in its infancy, and little was known about the chemistry of foods. Workers in the food business were trained in the need for sanitation. The adulteration of food was common.

Control of Microorganisms by Retarding Growth

By altering the factors (discussed in Chapter 4) to retard or inhibit the growth of microorganisms, the storage life of foods can be extended. These factors included temperature, water activity, acidity, oxidation-reduction potential, chemical inhibitors, and microbial interactions. Besides these factors, microorganisms can be affected by electrical current (Shimada and Shimahara 1981) as well as homologous phage (Greer 1986).

Control of Microorganisms by Destruction

The death of some microbial cells occurs during refrigeration, freezing, drying, or chemical treatment. However, these systems are not expected to produce a sterile food. Sterilization is considered to be a process by which all forms of life are destroyed. When subjected to a lethal process, a bacterial culture is reduced at a rate that is approximately logarithmic. This indicates a first-order reaction. The inactivation or death of cells can be determined by theformula

Gas-Liquid Chromatographic Differentiation Between Salmonella gallinarum and Salmonella pullorum

K=\frac{\log a-\log b}{t}

Microorganisms Associated with Food

where K is the death rate, a is the initial number of organisms, and b is the number of cells remaining at time t.

Factors That Affect Microbial Growth in Food

Five systems were compared for their ability to break up chains and clumps of organisms for enumeration. The highest aerobic plate counts of Bacillus cereus were obtained by mixing the organism in the Waring blendor or the Osterizer. Significantly lower counts were obtained by stomaching, shaking or shaking with beads. Results similar to those of B. cereus were obtained when Staphylococcus aureus and Streptococcus faecalis were prepared for enumeration using these five systems. There was no significant difference in aerobic plate counts obtained by using the five systems with Yersinia enterocolitica as the test organism.

Enumeration of Enterococci and Aerobic Mesophilic Plate Count in Dried Soup Using Three Reconstitution Methods

Salmonella gallinarom and Salmonella pullorom have been considered as one serovar, S. gallinarom-pullorom or S. gallinarom . This serovar possesses group D somatic antigens with no flagellar antigen. Reportedly S. gallinarom differs from S. pullorom in dulcitol fermentation. This reaction is positive, but delayed up to 5 d for S. gallinarom and negative for S. pullorom . Gas-liquid chromatography of organic acid by-products from a dulcitol medium was performed on 10 isolates of each biovar. Viable plate counts confirmed approximately the same number of organisms per ml of culture. Results of pH determinations supported gas-liquid chromatographic analysis of more acid formation in all S. gallinarom cultures as compared with the S. pullorom cultures after incubation for 24 h. A quantitative measurement of succinic acid resulted in confirmation of the differences in metabolic function of both biovars. The additional test procedure of gas-liquid chromatography of organic acid by-products aids the clinician or researcher in rapidly and accurately distinguishing these two similar biovars.

Control of Microorganisms

Throughout our lifetimes we are subjected to risks and hazards of all kinds. The food supply in the United States is one of the most abundant, nutritious, and safest on earth. However, there is no absolute degree of safety, not even for the food we consume.