Inactivation of Pseudomonas fluorescens and Streptococcus thermophilus in Trypticase® Soy Broth and total bacteria in milk by continuous-flow ultrasonic treatment and conventional heating

Villamiel, Mar; Jong, Peter de

doi:10.1016/s0260-8774(00)00059-5

Cited by 137 publications

(81 citation statements)

References 18 publications

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“…The results obtained from this study compare well with some of the results reported by Villamiel and de Jong [45]. They reported log reductions of between 0.6 and 4.2 for Ps.…”

Section: Pseudomonas Fluorescenssupporting

confidence: 91%

“…In addition to this, they used ultrasound in combination with a heat treatment. The differences in treatment parameters used in this study compared with those used by Villamiel and de Jong [45] make it difficult to explain why they obtained such a very low log reduction (0.6) in some cases.…”

Section: Pseudomonas Fluorescensmentioning

confidence: 56%

“…), and omitting or neglecting to mention them makes comparisons between the results of different research groups difficult. The statement that Gram-positive bacteria are more resistant to the detrimental effect of ultrasound [18,45] certainly holds true for the three strains tested in this study. Listeria monocytogenes showed more resistance, and longer D US -values compared to the two Gram-negative microbes tested.…”

Section: Listeria Monocytogenesmentioning

confidence: 57%

“…Other advantageous effects of ultrasonic waves in milk include: fat may be homogenised [5,45]; gases are removed [28]; and the antioxidant activity enhanced [40]. Villamiel and de Jong [45] reported that continuous-flow ultrasonic treatment could be a promising technique for milk processing.…”

Section: Introductionmentioning

confidence: 99%

“…Villamiel and de Jong [45] reported that continuous-flow ultrasonic treatment could be a promising technique for milk processing.…”

Section: Introductionmentioning

confidence: 99%

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Impact of ultrasound on dairy spoilage microbes and milk components

Cameron

McMaster

Britz

2009

Dairy Sci. Technol.

132

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-Numerous reports in the literature suggest pasteurisation failures in the dairy industry as a possible cause for an end product with a poor quality. Ultrasonication offers the dairy industry a non-thermal alternative to pasteurisation. The aim of this study was to evaluate the use of ultrasonication as an alternative to heat pasteurisation. Ultrasound was found to eliminate spoilage and potential pathogens to zero or to levels acceptable by South African and British milk legislation, even when initial inoculum loads of 5× higher than permitted were present before treatment. Viable cell counts of E. coli were reduced by 100% after 10.0 min of ultrasonication. The data obtained also showed that viable counts of Pseudomonas fluorescens were reduced by 100% after 6.0 min and Listeria monocytogenes was reduced by 99% after 10.0 min. An infra-red based apparatus was used to analyse raw and pasteurised milk after an ultrasonic treatment. Ultrasonication did not lead to decreases in the protein or lactose content of both raw and pasteurised milk. Kjeldahl nitrogen determinations confirmed that ultrasonication had no detrimental effect on the total protein or casein content of pasteurised milk. This study indicated that ultrasonication lead to an increase in the fat concentration. This was explained by the larger surface area of the fat globules after ultrasonication, which led to an increase in light scattering as observed by the MilkoScan. Alkaline phosphatase and lactoperoxidase activities were also investigated as potential indicators of an effective ultrasonic treatment. Ultrasonication was, however, found to be ineffective in deactivating both enzymes used regularly by the dairy industry as indicators of effective thermal processes. Résumé -Impact des ultrasons sur les microbes d'altération du lait et sur ses composants.De nombreuses publications suggèrent que dans l'industrie laitière, la mauvaise qualité du produit fini peut provenir de défaillances de la pasteurisation. Le but de cette étude a été d'évaluer l'utilisation de l'ultrasonication comme alternative au traitement thermique. Les résultats ont montré que les ultrasons éliminaient totalement, ou à des niveaux acceptables par la législation sud-africaine et anglaise, la flore d'altération et les pathogènes potentiels, et ce même quand les charges d'inoculum initiales avant traitement étaient 5 fois supérieures à celles autorisées. La réduction du nombre de cellules viables après ultrasonication était de 100 % après 10.0 min pour E. coli, de 100 % après 6.0 min pour Pseudomonas fluorescens et de 99 % après 10.0 min pour Listeria monocytogenes. L'analyse par infrarouge du lait cru et du lait pasteurisé après traitement aux ultrasons ne montrait aucune diminution de la teneur en protéines et en lactose dans ces deux laits. La quantification de l'azote par Kjeldahl confirmait l'absence d'effet préjudiciable de l'ultrasonication sur les teneurs en protéines totales ou en caséines du lait pasteurisé. Cette étude montre que l'ultrasonication conduit à ...