Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Poultry egg is basic ingredient
Reexamination Certificate
2000-01-14
2002-09-24
Weier, Anthony J. (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Poultry egg is basic ingredient
C426S330100, C426S521000, C426S298000, C426S300000
Reexamination Certificate
active
06455094
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods of treating food products, more particularly, methods of heat-treating food products.
BACKGROUND OF THE INVENTION
Contamination of shell eggs and egg products with Salmonella is a major public health concern. It is believed that Salmonella infection of shell eggs occurs either by transovarian transmission to the developing follicles or by trans-shell contamination from environmental sources (R. G. Board et al., (1996)
J. Applied Bacteriology
29:319). Until recently, however, no effective and commercially-feasible methods for reducing or eliminating Salmonella in shell eggs have been available.
The greatest food safety challenge facing the shell egg industry is the now clearly established linkage between the consumption of undercooked shell eggs and outbreaks of salmonellosis caused by
Salmonella enterica
serovar Enteritidis (SE). This serovar first emerged as a public health challenge in Europe in the 1920s, where SE foodborne illnesses were frequently traced to the consumption of duck eggs (Tauxe, (1999) Salmonella Enteritidis: the continuing global public health challenge. In Saeed, A. M. (ed.)
Salmonella enterica
serovar Enteritidis in Humans and Animals: Epidemiology, Pathogenesis, and Control. Iowa State Univ. Press (Ames, IA)). In the United States, highly invasive strains of SE began to establish themselves within flocks of egg-laying chickens in the Northeast in the late 1970s. SE may contaminate the internal contents of the egg via a transovarian transmission route or, under certain conditions, by passage through the shell exterior. The first large, United States multi-state SE outbreak linked to shell eggs occurred in 1986. In 1988, St. Louis et al. published a breakthrough epidemiological review paper that documented that SE was much more likely to be associated with egg-containing foods than were other serovars, that the eggs involved were nearly always U.S. grade-A commercial shell eggs, that the eggs were sourced from many different flocks, and that they were typically not fully cooked (St. Louis et al., (1988)
J. Amer. Med. Assoc.
259:2103). In the ensuing years, this problem has grown to the extent that outbreaks of egg-associated SE illness have been documented throughout the United States and in many other regions of the world, causing what the Centers for Disease Control and Prevention has characterized as a “growing worldwide pandemic” (Tauxe; supra). SE is also now the serovar most frequently isolated from patients with salmonellosis in the U.S. and in many nations around the world.
Since 1990, the U.S. Food and Drug Administration has designated grade A shell eggs as a “potentially hazardous food,” due to their proven linkage to outbreaks of SE foodborne illness (FDA, (1990) Potentially hazardous Food—shell eggs.
Retail Food Protection Program Information Manual.
FDA, Center for food Safety and Applied Nutrition. Washington, DC: U.S. Government Printing Office). SE has emerged as a significant public health concern for several reasons. First has been the emergence, for unknown reasons, of multiple strains and phage types of SE capable of infecting the reproductive tissues of egg-laying hens, without causing morbidity to the host, and without reducing egg production rates. Second is the fact that commercial egg handling practices have changed very little over the last 40 years. Inconsistent and poorly controlled egg handling, shelf-life dating, and transport practices permit eggs stored for extended periods of time at varying temperatures to be marketed to the consumer. In Europe, eggs are typically distributed and marketed at ambient temperatures. Eggs handled in this manner may contain elevated levels of SE bacteria relative to fresh eggs stored under refrigeration throughout their shelf-life. Third is the now well-established fact that many traditional egg cooking procedures are inadequate to assure the inactivation of SE in eggs and egg-containing foods (Saeed and Koons, (1993)
J. Food Protect
56:927). As a result of these concerns, the 1997 edition of the Food Code strongly recommends the use of pasteurized eggs and/or egg products in higher-risk recipes, and whenever highly susceptible populations (preschool children, the elderly, the immunocompromised) are served recipes prepared using eggs.
Pasteurization of shell eggs has been a challenge for the egg processing industry because of the physical structure of the intact egg and the susceptibility of egg proteins to heat denaturation. Egg proteins are sensitive to heat treatment, which may result in a loss of egg functionality (e.g., impairment in egg quality and properties), protein coagulation, or even partial cooking of the egg. The albumen proteins are particularly susceptible to heat damage (R. P. Elliott et al., (1980) Eggs and egg products. In
Microbial Ecology of Foods,
Vol. II,
Food Commodities.
International Commission on Microbiological Specifications for Foods. pp. 521-566. New York: Academic Press).
Typical pasteurization methods employ hot aqueous solutions, hot oil, or hot dry air to apply heat to the outside of the shell egg, such that the heat is then transmitted to the inner contents of the egg. Thus, there is a lag in the heating of the inner layers of the egg as compared with the outer layers. Accordingly, to impart a sufficient thermal treatment (i.e., time and temperature) to the center of the yolk to achieve Salmonella kill the albumen must be subjected to a greater total thermal treatment than the yolk. It therefore requires careful optimization of processing conditions to achieve a sufficient level of Salmonella kill throughout the egg without impairing egg quality and functionality, in particular, the quality and functionality of the albumen.
In recent years, several research groups have attempted to develop methods to pasteurize the internal contents of shell eggs without significantly changing the appearance, color, texture, aroma or flavor of the eggs. It has been demonstrated that immersion heat treatments in hot aqueous solutions can be used to produce high-quality Salmonella-free shell eggs (J. D. Schuman et al., (1997)
J. Applied Microbiology
83:438; PCT Publication No. WO 95/18538 to Vandepopuliere). These investigations identified time-temperature relationships necessary to inactivate Salmonella spp. within intact shell eggs, while preserving—to the greatest extent possible—the appearance, flavor and cooking performance of unheated eggs. However, pasteurization methods employing liquid immersion or spray-washing of shell eggs are not permitted under certain regulatory schemes (for example, many European countries), thus creating a need for alternative methods of pasteurizing shell eggs.
Another research group has published the results of experiments designed to inactivate
Salmonella enteritidis
in intact shell eggs by (1) immersion in a pre-heated 57° C. (134.6° F.) water bath for up to 25 minutes, (2) placement of eggs in a pre-heated 55° C. (131° F.) dry hot-air oven with a forced air circulating fan for up to 180 minutes, or (3) use of a combination of methods (1) and (2), i.e., water-bath heating at 57° C. (134.6° F.) for 25 minutes followed by hot-air heating at 55° C. (131° F.) for 60 minutes (H. Hou et al., (1996)
Food Microbiology
13:93). This group concluded that the combination method of heating in hot water followed by dry heated air (method (3) above) was the most commercially-feasible approach to pasteurizing shell eggs. PCT Patent Publication WO 97/02751 to Singh et al. (assigned to Purdue University) relates to this work and describes a method of heating intact eggs using a liquid or gas, or a combination of the two. A bulletin published by the Electric Power Research Institute (“Shell Egg Pasteurization”, Food Technology Alliance, 1997) describes the work by Hou and coworkers at Purdue using hot air to heat shell eggs.
The work of Hou et al., (1996)
Food Microbiology
13:93 (described above) demonstrates problems associated with heating shell eggs in a hot dry air
Ball Hershell R.
De Meester Fabien
Schuman James D.
Michael Foods, Inc.
Myers Bigel & Sibley & Sajovec
Weier Anthony J.
LandOfFree
Treatment of food products using humidity controlled air does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Treatment of food products using humidity controlled air, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Treatment of food products using humidity controlled air will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2897323