Buffers of Milk and Buffer Value

Buchanan, John; Peterson, E. E.

doi:10.3168/jds.s0022-0302(27)93836-3

Cited by 16 publications

(6 citation statements)

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“…Several authors have defined the elements contributing to the buffering capacity of milk as being mainly due to soluble phosphate, colloidal calcium phosphate, citrate, bicarbonate, caseins and whey proteins (Bimlesh Mann, & Malik, 1996;Buchanan & Peterson, 1927;Kirchmeier, 1980;Lucey et al, 1993c;McIntyre, Parrish & Fountaine, 1952;Rao & Dastur, 1956;Singh et al, 1997;Srilaorkul et al, 1989;Walstra & Jenness, 1984;Watson, 1931;Whittier, 1929;Wiley, 1935a, b). According to these authors, cow's milk constituents contribute differently to its buffering capacity (Table 2).…”

Section: Article In Pressmentioning

confidence: 96%

Buffering capacity of dairy products

Salaun

Mietton²,

Gaucheron

2005

International Dairy Journal

304

191

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Section: Article In Pressmentioning

confidence: 96%

Buffering capacity of dairy products

Salaun

Mietton²,

Gaucheron

2005

International Dairy Journal

304

191

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“…Buchanan and Peterson (2) used this method of expressing the buffer capacity of milk. They found a maximum value of 0-0326 in the region 5-0-5-5 falling to a minimum of 0-00635 between pTL 8-0 and 8-5.…”

mentioning

confidence: 99%

95. A Study of the Titratable Acidity of Milk. II. The “Buffer Curves” of Milk

Wiley

1935

Journal of Dairy Research

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THE previous section of this study in which the titration curves of various milk constituents were discussed approximately denned their influence on the titration. Some of the conclusions arrived at are amplified and more clearly defined when the buffer index of the curves is considered.In this discussion Van Slyke's(i) buffer index will be used, i.e. dBjdpK, the ratio of the change in normality of acid or base to the corresponding change in pE. when the change of pH. is infinitely small. The values recorded in this paper were obtained by measuring the slopes of the corresponding titration curves.Buchanan and Peterson (2) used this method of expressing the buffer capacity of milk. They found a maximum value of 0-0326 in the region 5-0-5-5 falling to a minimum of 0-00635 between pTL 8-0 and 8-5. While the general shape of their buffer curve has been confirmed by the following work they draw some rather surprising conclusions from it. They state that there is a great similarity between the titration curves of milk and sodium phosphate and that therefore "phosphates are at least among the most important buffers of milk." While the conclusion is undoubtedly correct, sufficient work has been described in the previous section of this study to show that there is little similarity between the two curves. They also claim that, as the value of the buffer index is not affected greatly near the isoelectric point of the casein, the casein can have little effect on the buffering in this region, pK 4-5-5-0. On the other hand, Whittier (3) comes to the opposite conclusion, i.e. that the buffer action of the casein is exerted principally between pH 4-50 and 5-70 with a maximum at approximately pB. 5-20. This follows from a consideration of the buffer curves of milk and of the acid whey prepared from it. Whittier considers that the difference between these two curves shows the effect of casein.Whittier was concerned particularly with the region between pH. 4 and 7 and did not consider the more alkaline portion of the curves. Moreover, he reached a condition of approximate equilibrium in making the titrations, so that his results are not applicable to the rapid titration of milk to the phenolphthalein end-point. Unless otherwise noted the curves in the following work were obtained from titrations made in the manner described in the previous

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“…The decrease in pH of milk can be explained by addition of H + which occurs by splitting of water molecules at the BPM cationic interface during electrochemical acidification of milk. The slow acidification of milk can be explained by its buffer capacity (i.e., proteins, weak acids) and the release of phosphate anions from the casein micelles, which neutralize the acidification effect of the H + addition [22]. Indeed, with decrease of pH, protein-bounded calcium (or magnesium) phosphates (or citrates) compounds convert to the soluble ionic form and remain in the whey fraction of milk [23].…”

Section: In Skim Milkmentioning

confidence: 99%

Impacts of Flow Rate and Pulsed Electric Field Current Mode on Protein Fouling Formation during Bipolar Membrane Electroacidification of Skim Milk

et al. 2020

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Fouling is one of the major problems in electrodialysis. The aim of the present work was to investigate the effect of five different solution flow rates (corresponding to Reynolds numbers of 162, 242, 323, 404 and 485) combined with the use of pulsed electric field (PEF) current mode on protein fouling of bipolar membrane (BPM) during electrodialysis with bipolar membranes (EDBM) of skim milk. The application of PEF prevented the fouling formation by proteins on the cationic interface of the BPM almost completely, regardless of the flow rate or Reynolds number. Indeed, under PEF mode of current the weight of protein fouling was negligible in comparison with CC current mode (0.07 ± 0.08 mg/cm2 versus 5.56 ± 2.40 mg/cm2). When a continuous current (CC) mode was applied, Reynolds number equals or higher than 323 corresponded to a minimal value of protein fouling of BPM. This positive effect of both increasing the flow rate and using PEF is due to the facts that during pauses, the solution flow flushes the accumulated protein from the membrane while in the same time there is a decrease in concentration polarization (CP) and consequently decrease in H+ generation at the cationic interface of the BPM, minimizing fouling formation and accumulation.

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Buffers of Milk and Buffer Value

Cited by 16 publications

References 0 publications

Buffering capacity of dairy products

Buffering capacity of dairy products

95. A Study of the Titratable Acidity of Milk. II. The “Buffer Curves” of Milk

Impacts of Flow Rate and Pulsed Electric Field Current Mode on Protein Fouling Formation during Bipolar Membrane Electroacidification of Skim Milk

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