Microbial shelf life

Corbo MR, Bevilacqua A, Campaniello D, D Amato D, Speranza D and Sinigaglia N. 2009. Prolonging microbial shelf life of foods through the use of natural compounds and non-thermal approaches - a review. Int J Food Sci Technol 44 223-241. 

Liu and Li studied the microbial proliferation and sensory quality aspects of sliced onions at different temperatures (2, 4 and 10°C) and atmospheric conditions (with or without 40% CO + 59% Nj +1% O ) and observed extended microbial shelf life in the MA (2006). The shelf life of the mriltiplier onion in the peel form could be increased from 4-5 days to 14 days in MA developed by the combined effect of silicone membrane (6 cm kg" ) and low temperature (5 1°C) (Naik et al., 2012). 

Toasted or crispbreads have prolonged microbial shelf life because they generally contain approximately 6% water equivalent or an of less than 0.5 and a pH below 5. The dehydration toasting process enhances staling and the crispy and brittle texture that characterize crispbreads. Fresh bread normally contains from 32% to 35%... 

Two other broad areas of food preservation have been studied with the objective of developing predictive models. En2yme inactivation by heat has been subjected to mathematical modeling in a manner similar to microbial inactivation. Chemical deterioration mechanisms have been studied to allow the prediction of shelf life, particularly the shelf life of foods susceptible to nonen2ymatic browning and Hpid oxidation. 

Sorbate combined with mild heat has a synergistic effect with regard to microbial destmction thus, in the presence of 0.025—0.06 wt % sorbate, products such as apple juice, peach and banana sHces, fmit salads, and strawberries can be treated with less severe heat treatments to extend shelf life (119,120). Sorbates increase the heat sensitivity of various spoilage fungi under varying conditions of pH and water activity (121—124). A similar synergistic effect has been reported for the combination of sorbate with irradiation (125). 

Eor fresh poultry, a potassium sorbate dip significantly reduces total viable bacteria and doubles the refrigerated shelf life of ice-packed broilers (133). In cooked, uncured, vacuum-packaged turkey and poultry stored at 4°C, 0.2—0.25 wt % potassium sorbate suppresses microbial growth for up to 10 days (134). Sorbic acid at 0.5% in a marinade mixture for chicken dmmmettes extends refrigerator shelf life (135). Country-cured hams sprayed with a 10 wt % potassium sorbate solution showed no mold growth for up to 30 days (136). A review of sorbate use in meat and fish products has been pubHshed (137). 

Hospital steriliza tion is more limited in the availabiHty of steriliza tion methods and of packaging materials. Microbial invasion can occur particularly when articles are wrapped in traditional fabrics such as muslin (140-thread-count cotton). The expected shelf life of hospital-wrapped and sterilized articles is considered to be ca 21—30 days when a double-wrapping technique is used. Double-wrapping requires two successive wraps, each having a layer or layers of an approved packaging material. 

Typical attributes for evaluating food quality are safety, shelf life, color, taste, flavor, texture, health, and convenience. The level of a quality attribute is determined by levels of physical, microbial, physiological, chemical, and biochemical food processes, product composition, and applied technological conditions. For example, a combination of enzyme-degrading colorants, compositions and concentrations of pigments, and food structure properties contribute to a certain color level perceived by consumers. Depending on the match of expectation and experience, certain attributes will or will not be perceived as quality. ... 

Calibration and maintenance programs [45], challenge tests [2], accelerated shelf life tests [53], auditing [2], sensory tests [46], microbial tests [47]... 

The restricted shelf life of liquid milk continues to be a problem that is often more influenced by the type of milk being sold rather than the pasteurisation technique. The shelf life of processed milk is determined primarily by the quality of the raw milk from the dairy herd. Increasing cell counts in the milk and a higher concentration of free fatty acids, contribute to rancidity in both liquid milk and milk products. Janzen (1972) reported that the 0-14 day shelf life of pasteurised milk is influenced by the somatic cell concentration in the raw milk and found that after 14 days any observed changes in the flavour and stability of the milk were attributable to microbial activity during storage. 

Microbial spoilage appears to be one of the major causes of quality loss of fresh fruits and vegetables by formation of off-flavors, fermented aromas, and tissue decay. The shelf-life of many food products may be accurately predicted by quantifying the population of microbes present on the food product (Zhuang and others 2003). The... 

Sinigaglia M, Albenzio M and Corbo MR. 1999. Influence of process operations on shelf life and microbial populations of fresh cut vegetables. J Ind Microbiol Biotechnol 23 484-488. 

Predictive microbiology using growth models should be implemented in order to follow the microbial behavior in fruit osmotically dehydrated/ impregnated and to compute their shelf life as a function of process variables, such as concentration of osmotic medium, initial contamination of the solution, and fruit storage temperature. 

Microbial biocatalytic systems, 76 398 Microbial biocontrol agents, 73 347-348 foliar application of, 73 349 phytotoxin production and, 73 351 problems associated with, 73 348-349 shelf life and storage of, 73 350 Microbial biomass, 26 471 474 substrates for, 26 473-474 Microbial catalysts, rapid screening of, 76 405... 

A preservative is a substance that prevents or inhibits microbial growth and extends the shelf life of the drug products. In most pharmaceutical drug products, only a few compounds are typically selected as preservatives. For efficiency, a generic method should be developed for the types of preservatives that are more commonly used. For example, butylated hydroxytoluene (BHT) is an antioxidant commonly used in many solid dosage formulations to retard oxidative degradation of the excipients. 

---