Extended shelf life milk—advances in technology

Rysstad, Gunnar; Kolstad, Jens

doi:10.1111/j.1471-0307.2006.00247.x

Cited by 127 publications

(101 citation statements)

References 6 publications

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“…However, 21.4% of pasteurized milk had TVC greater than the acceptable national limit [19]. High counts in pasteurized packed milk could possibly result from poor microbiological quality of the raw milk used and storage at elevated temperatures [32]. Poor microbiological quality of raw milk and storage at ambient temperatures has been observed to affect the shelf-life of the eventual pasteurized milk [33,34].…”

Section: Discussionmentioning

confidence: 99%

Microbiological quality and safety of raw and pasteurized milk marketed in and around Nairobi region

Wanjala¹,

Mathooko²,

Kutima³

et al. 2017

AJFAND

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The microbiological quality of raw and pasteurized milk marketed in Nairobi and its environs was determined. Milk samples were collected randomly at milk selling points from three market areas: rural (Kiambu/Ngong), urban (East/West of Tom Mboya street) and slum (Kibera/Mathare). Samples were analysed for titratable acidity, total viable count (TVC), Staphylococcus aureus, coliforms and Enterobacteriaceae. Titratable acidity was determined using titration method, while TVC, S. aureus and Enterobacteriaceae were determined by the spread plate methods and coliforms were determined by most probable number. Data collected were subjected to analysis of variance using Genstat statistical package. The mean acidity was 0.20% lactic acid (LA), while mean counts for TVC, S. aureus, coliforms and Enterobacteriaceae were 6.05, 3.46, 2.30, and 3.93 log10cfu/ml, respectively. The percentage of milk samples with acidity values greater than 0.18% LA, the upper limit set by Kenya Bureau of Standards (KEBS), was 52.8 %. Total viable count (TVC) greater than 10 6 cfu/ml, was detected in 95.2% and 21.4% of raw and pasteurized milk, respectively. Coliform counts greater than 4.70 and 1.0 log10cfu/ml for raw and pasteurized milk were detected in 77.8% and 4.8%, respectively of raw and pasteurized milk samples collected. Enterobacteriaceae and S. aureus were detected with mean counts ranging from 6.08-6.86 and 5.82-6.32 log10/ml, respectively. Highest mean acidity and counts were recorded from slum areas of Nairobi and there were significant differences between raw and pasteurized milk (P<0.05). The poor bacterial quality coupled with high acidity of raw milk, indicates poor hygienic practices and lack of temperature control during marketing. The incidence of high acidity and bacterial counts in pasteurized milk could indicate post process contamination and/or inappropriate storage of the milk. Most vendors of pasteurized milk were observed selling directly from the distributor crates without refrigerated storage. The rapid deterioration of raw and pasteurized milk marketed in Nairobi, at the time of this study, may be largely due to poor hygienic standards and non-adherence to temperature controls during handling, distribution and marketing. This requires urgent attention by the appropriate authorities, because the poor microbiological quality of raw milk and pasteurized milk may expose consumers to health risks associated with the consumption of contaminated milk.

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Section: Discussionmentioning

confidence: 99%

Microbiological quality and safety of raw and pasteurized milk marketed in and around Nairobi region

Wanjala¹,

Mathooko²,

Kutima³

et al. 2017

AJFAND

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“…Obviously, ESL milk samples of poor quality had been manufactured using an indirect UHT process that had been reported to be cheaper (regarding investment and production costs) and more energy-efficient compared to the direct UHT heating techniques using injection or infusion systems. On the other hand, directly UHT-treated ESL milk suffers less heat damage than indirectly heated milk and can therefore be used in the production of ESL milk as an alternative to modern microfiltration techniques [10,15,18,24,25].…”

Section: Comparison Of Acid-soluble β-Lgmentioning

confidence: 99%

“…127°C for 2-3 s), or in many cases also indirect heat treatment (e.g. 125°C for 2 s) [15,18,24,25]. However, heating causes a significant loss of organoleptic and nutritional quality (e.g.…”

Section: Introductionmentioning

confidence: 99%

RP-HPLC analysis of furosine and acid-soluble β-lactoglobulin to assess the heat load of extended shelf life milk samples in Austria

Mayer

Raba

Meier

et al. 2010

Dairy Sci. Technol.

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-Recent trends to extend the shelf life of pasteurized milk, without the negative flavour normally associated with ultra-high-temperature (UHT) milk, have resulted in the development of extended shelf life (ESL) milk. Acid-soluble β-lactoglobulin (β-Lg) and furosine contents were chosen as relevant indicators for heat load of ESL milk products. RP-HPLC methods were developed using the same column (Symmetry 300™, Waters), which enabled the separation of whey proteins within 22 min; furosine was analysed using ion-pair RP-HPLC within 8 min. Electrophoresis was used as a high-throughput and cost-effective screening method to assess the impact of thermal processes on milk and to distinguish different categories of heat-treated milk samples. Liquid milk samples (n = 128; including 7 raw, 33 pasteurized, 71 ESL, and 17 UHT milk samples) were obtained from retail outlets in Austria and analysed. Only 45% of the analysed samples designated as ESL milk showed furosine contents < 40 mg·100 g −1 protein as well as acid-soluble β-Lg contents > 1800 mg·L −1 milk, which had been discussed as threshold levels for ESL milk. A further 55% of the analysed ESL milk samples had low acid-soluble β-Lg (< 500 mg·L −1 ) and high furosine contents (> 40 mg·100 g −1 protein), levels comparable to the excessive heat load of UHT milk. Thus, there is an urgent need for an EU regulation to define legal limits for the tolerable heat load of ESL milk as soon as possible.extended shelf life milk / β-lactoglobulin / furosine / RP-HPLC / electrophoresis Article published by EDP Sciences Résumé -Analyse de la furosine et de la β-lactoglobuline soluble à pH acide par RP-HPLC pour évaluer la charge thermique de laits de longue conservation en Autriche. La tendance actuelle visant à allonger la durée de conservation du lait pasteurisé, sans avoir les défauts de flaveur habituellement associés au lait UHT, a conduit au développement du lait de longue conservation ESL. Les concentrations en β-lactoglobuline soluble à pH acide (β-Lg) et en furosine ont été choisies comme indicateurs pertinents de la charge thermique des produits laitiers ESL. Des méthodes RP-HPLC ont été développées avec la même colonne (Symmetry 300™, Waters), qui a permis de séparer les protéines sériques en 22 min ; la furosine était analysée par RP-HPLC en paire d'ions en 8 min. L'électrophorèse a été utilisée comme méthode économique de criblage à haut débit pour évaluer l'impact des traitements thermiques sur le lait et pour distinguer différentes catégories d'échantillons de lait traité thermiquement. Les échantillons de lait liquide (n = 128 ; comprenant 7 échantillons de lait cru, 33 pasteurisé, 71 ESL et 17 UHT) ont été prélevés dans des points de vente en Autriche et analysés pour leur teneur en β-lactoglobuline et furosine. Seulement 45 % des échantillons analysés désignés comme lait ESL présentaient des teneurs en furosine inférieures à 40 mg·100 g −1 de protéine et des teneurs en β-lactoglobuline soluble à pH acide supérieures à 1800 mg·L, valeurs qui ont été disc...

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“…If milk is kept below 5 °C, then these pathogens are unable to grow. A general rule for pasteurized milk is that every 2 °C increase in temperature reduces the expiry date by 50% (Rysstad & Kolstad, 2006).…”

Section: Introductionmentioning

confidence: 99%

The effectiveness of common methods of cold-holding on the temperature of milk

Perrella

Meldrum

Moos

et al. 2017

Environ. Health Rev.

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Keeping self-serve milk below 4 °C may become difficult for a food premise operator who relies on the use of insulated containers for several hours. Although milk sold in Canada is pasteurized, it may have the potential to cause illness if exposed to improper temperatures. The primary objective of this study was to demonstrate which product would be the most effective at keeping milk cold for the longest period to decrease the potential risk of foodborne illness. A survey was conducted in food premises throughout the Niagara region to determine which products were most commonly used for cold-holding milk, followed by a time-series analysis to investigate how rapidly the temperature of milk increased when stored in typical containers after 8 hours. Results showed that vacuum-insulated carafes are the most effective at cold-holding and stainless-steel carton holders are the least effective. The Niagara survey showed that 8 of 27 premises visited used these poorly insulated stainless-steel carton holders, which may be additionally susceptible to human contamination from potentially pathogenic bacteria such as Staphylococcus aureus due to their open spout.

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Extended shelf life milk—advances in technology

Cited by 127 publications

References 6 publications

Microbiological quality and safety of raw and pasteurized milk marketed in and around Nairobi region

Microbiological quality and safety of raw and pasteurized milk marketed in and around Nairobi region

RP-HPLC analysis of furosine and acid-soluble β-lactoglobulin to assess the heat load of extended shelf life milk samples in Austria

The effectiveness of common methods of cold-holding on the temperature of milk

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