454. Bacteriological aspects of the reworking and blending of stored butter

Hiscox, E. R.; House, Alistair

doi:10.1017/s0022029900006178

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“…Many foods consist of a fine admixture of aqueous and non-aqueous phases, the state of which is believed in some cases to affect their spoilage. It has been claimed (Mare;, 1934) that the character of the emulsion structure of margarine influences its microbial spoilage under a given set of conditions; and that a diminution of storage life follows the 'working' of butter because bacterial infection originally confined to a small proportion of the aqueous droplets is widely spread thereby (Hiscox & House, 1951).…”

Section: (Iv) Emulsion Structurementioning

confidence: 99%

The physiology of microbial spoilage in foods

Mossel

Westerdijk

1949

Antonie van Leeuwenhoek

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Section: (Iv) Emulsion Structurementioning

confidence: 99%

The physiology of microbial spoilage in foods

Mossel

Westerdijk

1949

Antonie van Leeuwenhoek

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Probleme der Butterverpackung

Kalkschmidt

1956

Fette, Seifen, Anstrichm.

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ausfiihrliche Arbeit von H . Righi erschienen4*, wodurch friiliere Versurhe von H . D. Tangermann 43 erganzt wurden.Das Verschliei3en bei hoheren Temperaturen, welches zu eintr Vergleichmaaigung d,es Sterilisierwertes der Dosenschichten fiihrt, erhoht den Unterdruck bei zu langem Abkiihlen, wahrend die bei der Entspannung bzw. Kiihlung entstehende Wirkdruckspitze bei groi3en fliissigkeitsfreien Raumen in der Dose, bei Gutern mit hohem Gasgehalt bedenklich werdcn kann, insbesondere bei hohen Abkiihlungsgeschwindigkeiten. Letztere sind auch im Hinblick auf die Vergleichmafligung der Sterilisierwerte in den einzelnen Schichten ungiinstig. Leider fehlt noch eine statistische Auswertung des Zusammenhangs zwischen technologischen Faktoren einerseits und Reklamationsfallen andererseits, obwohl der Sterilisierprozei3 zu einer solchen Auswertungsform geradezu herausfordert.Eine weitere Frage ist, in welchen Fallen eine schonende Durchfiihrung des Sterilisierprozesses im Hinblick auf die Nohe der Lagerveranderung lohnt. Ober die qualitativcn Veranderungen von Dosenkonserven wahren8d der Lagerung wenn man von der Wechselwirkung mit der Dosenwandung und von Vitamin-Verlusten44 absiehtgibt es merkwiirdigerweise ebenfalls nur wenig planmai3ige Versuche. D a aber die langdauernde Haltbarmachung das Ziel der Dosenkonservierung bildet, miifiten die qualitativen Unterschietle z. B. hoch-kurzsterilisierter bzw. nach iiblichen Methoden mit verschiedenen Sterilisierwerten haltbar gemachter Konserven zunachst einmal nach lingerer Lagerzeit festgestellt werden, bevor man den Sterilisierprozefi verfeinert, denn da, wo Lagerveranderungen entsch'eimdend sind, kann man moglicherweise zur Verminderung des Risikos auch eine gewisse ,.Ubersterilisierung" wagen. Qualitatsveranderungen konnen sich auch daraus ergeben, dai3 die Inaktivierungskurve z. B. fur Peroxydase flacher verlauft als die Abtotungskurve fur die hitzestahilsten fur die betreffenden Lebensmittel charakteristischen Mikroorganismen bzw., dai3 sich Enzyme bei der Lagerung regenerieren. Bei sauren Lebensmitteln kann die Inaktivierungskurve fur Mikroorganismen hoher liegen als die Abtotungskurven fur die iiblichen Mikroorganismenstamme 45. Wie vorsichtig das Gebiet zu handhaben ist, ergibt sirh aus der Feststellung, dai3 hoch,kurz-erhitzte evaporierte Milch schneller nachdickt als die nach dem ublichen Steri1.i-sierprozei3 haltbar gemachte, also zur Vermeidung des Nachdickens offensichtlich eine starkere Denaturierung der M,ilchproteine erforderlich ist 40.

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Section B. Bacteriology and mycology applied to dairying

Hiscox¹,

Briggs²

1953

Journal of Dairy Research

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Reviews of the progress of dairy sciencepreformed enzymes, are added to chemically defined substrates, giving clear-cut results. A clockwork automatic bacteriological inoculating device has been devised by Fuson & Marcus (20). An ingenious device(2i), patented in the U.S.A., for counting bacterial colonies, consists of a fountain pen connected to an electro-magnetic counter which registers each time the pen touches the Petri dish or roll-tube. Hannay (22) has described a new type of laterally illuminated colony counting chamber. British Standards for Petri dishes (23) have been issued recently. A microtechnique for the growth of many cultures, particularly for assay work, in one Petri dish has been developed by Turner-Graff(24). Newbould's(25) roll-tube spinner is designed to use cheap, easily obtainable vials or bottles. A suggestion contributing, in the long run, to economy is that of using rigid, seamless tubes of Kraft paper instead of the paper wrappings commonly used for individual sterile pipettes (26); Lack (27) has described a hot box for microcultures, which dispenses with a water jacket since the heating element consists of glass electrothermal heating tape. From America have come details of a simple large-scale anaerobic culture apparatus (28) utilizing a milk can as the main container, and of the uses to which spun glass (29) may be put as an air-filtering medium for bacteriological purposes.The text of the papers read, and the discussion, at a Symposium of the Institute of Biology in London in 1951 have been published under the title Freezing and Drying^); diversity of opinion and lack of collaboration and understanding between bacteriologist and vacuum engineer was apparent concerning even such vital factors as the plugs for drying tubes. Fry & Greaves (31), working mainly with a paracolon bacillus over a 3-year period, have shown that the nature of the suspending medium is one of the most important factors determining the survival rate of bacteria dried in vacuo; the addition of 5-10% of glucose or lactose increased the percentage survival. Young cultures were less resistant to drying than older cultures, but the cell concentration appeared to be of little consequence. ' Mist desiccans' (1 part broth, 3 parts serum with 7-5% added glucose) proved a satisfactory suspending medium for sensitive organisms such as Neisseria gonorrhoea. Briggs' observations (32) on the freeze-drying of lactobacilli are in almost complete agreement with those of Fry & Greaves; using strains of Lactobacillus acidophilus and L. bulgaricus, which were particularly sensitive to freeze-drying, she obtained with her suspending media survival rates of over 10% after 18 months' storage; her work is being continued with other species of lactobacilli subsequently tested to determine whether selection has taken place, although this should not be a danger except where very low survival rates are experienced. Sharpe (33) has tested the precipitin and agglutination reactions of cultures of L. acidophilus and L. bulgaricus which had b...

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454. Bacteriological aspects of the reworking and blending of stored butter

Cited by 5 publications

References 0 publications

The physiology of microbial spoilage in foods

The physiology of microbial spoilage in foods

Probleme der Butterverpackung

Section B. Bacteriology and mycology applied to dairying

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