Action of Microörganisms on Fats

Jensen, L. B.; Grettie, Donald P.

doi:10.1111/j.1365-2621.1937.tb16502.x

“…According to Jensen and Grettie (8) the rancidity produced by bacterial action most commonly involves two main types of chemical reactions, hydrolytic and oxidative. Flavor defects due to free fatty acids and oxidation products can be produced by single species capable of elaborating both hydrolytic and oxidative enzymes.…”

mentioning

confidence: 99%

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUS^a

Goldman¹,

Rayman²

1952

Journal of Food Science

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It is well known that the deterioration of fats in foods may be caused by the action of certain bacteria. According to Jensen and Grettie (8) the rancidity produced by bacterial action most commonly involves two main types of chemical reactions, hydrolytic and oxidative. Flavor defects due to free fatty acids and oxidation products can be produced by single species capable of elaborating both hydrolytic and oxidative enzymes. This paper is devoted to the investigation of some of the factors involved in the hydrolysis of fats by members of the genus Pseudomonas.Early studies on the action of microorganisms on fats have been reviewed by Jensen (7) and Lea (9). The work of Hammer and his colleagues (3, 6, 10) has shown that lipolytic bacteria of the Pseudomonas-Achromobacter groups are common in dairy products and cause flavor defects in butter.Laboratory methods for studying the bacterial metabolism of fats have not, in general, been too satisfactory for obtaining consistent, reproducible quantitative data. Accurate analytical methods need to be devised for measuring the amounts of metabolic products formed. Procedures for emulsifying fats in a stable state of ultra-fine particle size have been lacking. Practically all of the early studies have been made using emulsified fats of variable, uncontrolled particle size. I t has been demonstrated by Frazer and Walsh ( 4 ) that the rate of hydrolysis of a fat by lipase is proportional to the surface area and inversely proportional to the radii of the globules. I n a very fine emulsion the reaction curve approximates that of a substance in true solution. One improved technique to increase the reactive surface of fat substrates was used by Trussell and Weed (11) who studied the lipolysis of staphylococci. These workers employed a culture shaking machine which kept the fat particles from coalescing and provided fresh surface for enzyme reaction. In the present study a further improvement in methods for producing stable, highly dispersed, fat emulsion media is reported. MATERIALS AND METHODS MediaProduction of stable, finely-dispersed stock emulsions containing fats in concentrations as high as 25% is described below. From such stock emulsions it was convenient to make suitable dilutions with water to provide the desired experimental strengths in the media. The diluted emulsion substrate was sterilized in Erlenmeyer flasks by auto-'

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“…As Jensen and Grettie (1937) have suggested, food chemists would do well to give greater consideration to microbial action in studying oxidative as well as hydrolytic rancidity. This test is a very convenient method for identifying bacteria bringing about the oxidation changes.…”

Section: Discussionmentioning

confidence: 96%

“…In their work on the action of microorganisms on fats, Jensen and Grettie (1937) have shown that many of the so-called lipolytic organisms produce both lipases and oxidases. Several years' practical experience in this laboratory have indicated that most of the lipolytic organisms considered to be the cause of various types of rancidity show a marked oxidase reaction.…”

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confidence: 99%

“Oxidase Reaction” of Bacteria in Relation to Dairy Products

Castell¹,

Garrard²

1940

Journal of Food Science

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Relatively little attention has been paid to the "oxidizing capacity" of microorganisms in relation to the spoilage of dairy and other food products. Many bacteria have this ability to a marked degree. Recognition of this characteristic along with proteolytic, lipolytic, acid-forming, and other familiar bacterial activities would give a more accurate picture of bacterial action in the spoilage of food.In their work on the action of microorganisms on fats, Jensen and Grettie (1937) have shown that many of the so-called lipolytic organisms produce both lipases and oxidases. Several years' practical experience in this laboratory have indicated that most of the lipolytic organisms considered to be the cause of various types of rancidity show a marked oxidase reaction. Other organisms, in which enzymes capable of hydrolyzing fats are negligible or absent but which cause taints in butter, have been found to be strongly oxidase-positive. With these ideas in mind, a general survey has been made of the oxidase activity of some 30 species of organisms which are commonly or occasionally found in dairy products. These results are compared with the action of the same organisms on fats and their relative destructiveness in dairy products. THE OXIDASE TESTThe procedure followed for detecting oxidase-producing bacteria is based upon the methods described by Gordon and McLeod (1928) and Ellingworth, McLeod, and Gordon (1929). This consists of flooding petri plates in which organisms are growing with a .5 per cent aqueous solution of either p-aminodimethylaniline hydrochloride or tetramethyl-p-phenylenediamine hydrochloride. As soon as the agar surface has been completely covered with the dye solution it is poured off, and the petri plates are left with their covers removed. Freshly prepared, these dye solutions are almost colorless. After contact with these dyes, oxidase-forming colonies very shortly assume a deep color. With the tetramethyl compound this color is purple, and with the dimethyl compound it is rose-red. 21.5

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“…

The ability of bacteria to oxidize triglycerides has long been recognized (Orla-Jensen, 1902, Rahn, 1906, but the procedures for the detection of oxidative changes have been time-consuming, laborious, and not very reliable (Horowitz-Vlassova and Livschitz, 1935). The work of the latter authors, as well as that of Jensen and Grettie (1937), indicates that the common cultural procedure for the detection of degradation of triglycerides, namely, the streaking of organisms upon an agar medium into which oil or fat has been incorporated, does not indicate the ability of the bacteria to oxidize the lipides.Horowitz-Vlassova and Livschitz (1935) indicate two objections to the present methods of determining bacterial oxidation of triglycerides: the time consumed in incubation and in the performance of the various chemical determinations and the fact that in some instances the chemical determinations upon the derived fat or oil are influenced by the presence of carbohydrates or proteins in the medium.The present work is a study of the ability of a group of 32 widely distributed bacteria to oxidize a practically pure triglyceride as determined by the Warburg apparatus. Studies were also made to determine just how many of these bacteria had the ability to break down a triglyceride by means of oxidation and without hydrolysis since only one known species had been reported previously to possess this ability.

…”

mentioning

confidence: 97%

“…The ability of bacteria to oxidize triglycerides has long been recognized (Orla-Jensen, 1902, Rahn, 1906, but the procedures for the detection of oxidative changes have been time-consuming, laborious, and not very reliable (Horowitz-Vlassova and Livschitz, 1935). The work of the latter authors, as well as that of Jensen and Grettie (1937), indicates that the common cultural procedure for the detection of degradation of triglycerides, namely, the streaking of organisms upon an agar medium into which oil or fat has been incorporated, does not indicate the ability of the bacteria to oxidize the lipides.…”

mentioning

confidence: 97%

The Bacterial Oxidation of Corn Oil

Mundt

¹

,

Fabian

²

1944

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The ability of bacteria to oxidize triglycerides has long been recognized (Orla-Jensen, 1902, Rahn, 1906, but the procedures for the detection of oxidative changes have been time-consuming, laborious, and not very reliable (Horowitz-Vlassova and Livschitz, 1935). The work of the latter authors, as well as that of Jensen and Grettie (1937), indicates that the common cultural procedure for the detection of degradation of triglycerides, namely, the streaking of organisms upon an agar medium into which oil or fat has been incorporated, does not indicate the ability of the bacteria to oxidize the lipides.Horowitz-Vlassova and Livschitz (1935) indicate two objections to the present methods of determining bacterial oxidation of triglycerides: the time consumed in incubation and in the performance of the various chemical determinations and the fact that in some instances the chemical determinations upon the derived fat or oil are influenced by the presence of carbohydrates or proteins in the medium.The present work is a study of the ability of a group of 32 widely distributed bacteria to oxidize a practically pure triglyceride as determined by the Warburg apparatus. Studies were also made to determine just how many of these bacteria had the ability to break down a triglyceride by means of oxidation and without hydrolysis since only one known species had been reported previously to possess this ability. Finally a study was made of the correlation between ability of the organisms to oxidize a triglyceride and certain chemical tests used in connection with lipoidal materials. EXPERIMENTALThe ability of bacteria to oxidize corn oil was determined by means of the Warburg apparatus (Dixon, 1934) and by the Thunberg (1918) technique.The organisms were grown on the medium used by Nunheimer and Fabian (1941), composed of 0.2 per cent each of the following Bacto products: peptone, beef extract, yeast extract, and peptonized milk, and 1.5 per cent agar. The pH was adjusted to 7.0-7.2, and the medium was placed into large, flat bottles which offered a large surface exposure. Following inoculation and incubation at the optimum temperature of the individual species, the bacteria were washed three times with saline solution, and were then placed in suspension with 10 ml of saline solution per bottle. The suspension was thoroughly shaken, filtered through cotton, stored in the refrigerator, and aerated 30 minutes before use.

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Action of Microörganisms on Fats

Cited by 38 publications

References 21 publications

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUS^a

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUS^a

“Oxidase Reaction” of Bacteria in Relation to Dairy Products

The Bacterial Oxidation of Corn Oil

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Action of Microörganisms on Fats

Cited by 38 publications

References 21 publications

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUSa

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUSa

“Oxidase Reaction” of Bacteria in Relation to Dairy Products

The Bacterial Oxidation of Corn Oil

Contact Info

Product

Resources

About

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUS^a

HYDROLYSIS OF FATS BY BACTERIA OF THE PSEUDOMONAS GENUS^a