Spore Destruction Rate Studies on Organisms of Significance in the Processing of Canned Foods

Reed, J. Michael; Bohrer, C. Wallace; Cameron, E. J.

doi:10.1111/j.1365-2621.1951.tb17396.x

Cited by 69 publications

(38 citation statements)

References 5 publications

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“…3679 and Cl. botulinum spores has also been reported in vegetable substrates (10,17). F o r practical purposes, therefore, it would appear safe t o assume that processes calculated for z = 18 and providing Fo values equivalent to the observed P values for destruction of P. A.…”

Section: Discussionmentioning

confidence: 96%

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATES^a

Reynolds

Kaplan

Spencer

et al. 1952

Journal of Food Science

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Cameron's Putrefactive Anaerobe 3679 is widely used as a test organism to evaluate process requirements f o r low-acid canned foods. Although the thermal resistance of this organism is known to vary with the substrate in which it is heated (2, 15, 18), until recently (10, 16) there were relatively few data in the literature that defined the constants of thermaldeath-time curves of the organism in vegetable substrates. Most of these data specify the resistance of spores when heated in liquid extracts or purCed vegetables. Townsend, Esty, and Baselt (18) have emphasized the need f o r information based on work with raw products rather than with brines from processed foods, and data reported more recently by Reed, Bohrer, and Cameron (10) indicate that heat resistance of spores in a given vegetable substrate may cliff e r considerably, depending on whether the substrate is prepared as a pt1ri.e or as larger piwrs sixspended in brine.With respect to processes f o r nonpurked vegetables, it seems reasonable to assume that the latter medium would be superior to the p r 4 e in providing environmental conditions that simulate conditioiis to which spores are exposed in containers of vegetables during processing.The study reported in this article, was undertaken to augment currently available data by determining the constants of thermal-death-time curves of P. A. 3679 spores heated in 13 low-and medium-acid vegetables, chopped or cut.Terms and nomenclature used in this paper are coiisistent with those used by Ball ( 3 ) , Townsend, Esty, and Baselt (18), Sognefest and Benjamin ( 1 4 ) , Reed, Bohrer, and Cameron (ZO), and others. E X P E R I M E N T A L METHODSPreparation of spore suspensions. Spore suspensions of P. A. 3679 were prepared by culturing the organism in 10% egg-meat medium (Difco) a t 3OoC.(86"F.) f o r 3 weeks, filtering the medium through glass wool, centrifuging the filtrate, and suspending the spores in a small volume of sterile 0.5% peptone solution. Concentrated suspensions, containing 3 X lo8 to 3 X lo8 spores per ml., were distributed in 2 t o 4 ml. quantities in TDT (thermal-death-time) tnhes. The tubes were sealed and heated for 20 minutes at 1OO0C.(212"P.) (12) and held under refrigeration until used.Preparation of substrates. Both commercially frozen and fresh food samples were used for preparing food substrates. Frozen foods were thawed; fresh vegetables were washed, trimmed, and blanched. All samples, with the exception of asparagus and spinach, were chopped in a hand food chopperb. Asparagus and spinach were chopped

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Section: Discussionmentioning

confidence: 96%

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATES^a

Reynolds

Kaplan

Spencer

et al. 1952

Journal of Food Science

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“…Comparing the heat resistance characteristics of spores recovered in substrates supplemented with a growth medium with those recovered in unsupplemented substrates, Reed et al (72) observed that semiacid products exhibit an inhibitory effect upon the growth of the most heat-resistant spores, Reynolds et al (73) that the majority of the vegetables they examined exhibited an inhibitory effect on the germination of spores of PA 3679, and Kaplan et al (41) that higher thermal death times were observed when spores were recovered in food substrates modified with added peptone as compared with unmodified substrates. It is probable, then, that the observation of lower D 121.1uC -values in food substrates is attributable to both an increased sensitivity to the applied heat treatment and to an inhibition of recovery and/or germination or outgrowth of heat-injured spores.…”

Section: A Comparative Analysis Of the Heat Resistance Of Spores Of Pmentioning

confidence: 99%

Clostridium sporogenes PA 3679 and Its Uses in the Derivation of Thermal Processing Schedules for Low-Acid Shelf-Stable Foods and as a Research Model for Proteolytic Clostridium botulinum

Brown

Tran‐Dinh

Chapman

2012

Journal of Food Protection

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The putrefactive anaerobe Clostridium sporogenes PA 3679 has been widely used as a nontoxigenic surrogate for proteolytic Clostridium botulinum in the validation of thermal processes for low-acid shelf-stable foods, as a target organism in the derivation of thermal processes that reduce the risk of spoilage of such foods to an acceptable level, and as a research model for proteolytic strains of C. botulinum. Despite the importance of this organism, our knowledge of it has remained fragmented. In this article we draw together the literature associated with PA 3679 and discuss the identity of this organism, the phylogenetic relationships that exist between PA 3679 and various strains of C. sporogenes and proteolytic C. botulinum, the heat resistance characteristics of PA 3679, the advantages and limitations associated with its use in the derivation of thermal processing schedules, and the knowledge gaps and opportunities that exist with regard to its use as a research model for proteolytic C. botulinum. Phylogenetic analysis reviewed here suggests that PA 3679 is more closely related to various strains of proteolytic C. botulinum than to selected strains, including the type strain, of C. sporogenes. Even though PA 3679 is demonstrably nontoxigenic, the genetic basis of this nontoxigenic status remains to be elucidated, and the genetic sequence of this microorganism appears to be the key knowledge gap remaining to be filled. Our comprehensive review of comparative heat resistance data gathered for PA 3679 and proteolytic strains of C. botulinum over the past 100 years supports the practice of using PA 3679 as a (typically fail-safe) thermal processing surrogate for proteolytic C. botulinum.

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“…Studies with spores having a 10,000-fold range in heat resistance in dilute phosphate buffer (pH 7) showed, however, that these differences largely disappeared when the spores were heated in a partially dry state (Murrell & Scott, 1957). There is abundant evidence that spores and vegetative forms are more resistant when heated in substantially dry materials than when heated in dilute aqueous solutions (Oag, 1940;Reed, Bohrer & Cameron, 1951;Collier & Townsend, 1956;Townsend, Esty & Baselt, 1938). In most of these studies the moisture status of the substrate was not controlled, and the results did not provide quantitative evidence of the change in heat resistance with change in water content or water activity (aw).…”

Section: Introductionmentioning

confidence: 99%

Heat Resistance of Bacterial Spores at Various Water Activities

Murrell

Scott

1957

Nature

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SUMMARYThe heat resistance of the spores of six species of bacteria varied with water activity (a,) at which the spores were heated, although the magnitude of the changes differed greatly between species. At all a, values there was an approximately linear relation between the logarithm of the number of viable spores and the time of heating. The slopes of these straight lines were used to describe the observed death-rates as the time ( D value) required to decrease the population by one log. unit. For all six species the greatest heat resistance was manifest at a, values of about 0.2-0.4, the maximum D values at 110' varying from about 2 to 24 hr. A t a, values less than 0.2 the heat resistance decreased; for spores rigorously dried over P,O, (0.00 a,) the D values at 110" now varied between about 30sec. and 30min. When the spores were heated a t a, values above 0.4 the resistance of 4 species decreased considerably, being lowest at 1-00 a,; with spores of Bacillus coagulans and B. stearothermophilus the heat resistance decreased less at the high a, values; at 1.00 a, their D values were slightly greater than at 0.00 a,. At the high a, values the D values a t 110' varied from less than 0.1 sec. for Clostridium botulinum type E to about 40 min. for B. coagulans and B. stearothermophiZus. The Qlo for thermal death was about 10 at high a, values, decreasing to about 2 at a, values below 0-3. Under very moist conditions spores of B. stearothermophilus were about 50,000 times more heat resistant than were spores of C . botulinum type E ; but at a, values less than about 0.5 this ratio fell to about 10. The convergence of this ratio resulted from more than a 100,OOo-fold increase in the resistance of the type E spores, and only a 20-fold increase in the resistance of the spores of B. stearothermophilus.

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Spore Destruction Rate Studies on Organisms of Significance in the Processing of Canned Foods

Cited by 69 publications

References 5 publications

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATES^a

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATES^a

Clostridium sporogenes PA 3679 and Its Uses in the Derivation of Thermal Processing Schedules for Low-Acid Shelf-Stable Foods and as a Research Model for Proteolytic Clostridium botulinum

Heat Resistance of Bacterial Spores at Various Water Activities

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Spore Destruction Rate Studies on Organisms of Significance in the Processing of Canned Foods

Cited by 69 publications

References 5 publications

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATESa

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATESa

Clostridium sporogenes PA 3679 and Its Uses in the Derivation of Thermal Processing Schedules for Low-Acid Shelf-Stable Foods and as a Research Model for Proteolytic Clostridium botulinum

Heat Resistance of Bacterial Spores at Various Water Activities

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Product

Resources

About

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATES^a

THERMAL DESTRUCTION OF CAMERON'S PUTREFACTIVE ANAEROBE 3679 IN FOOD SUBSTRATES^a