What is the pH of milk?
By
Dr Rafael Frascino Cassaro (PhD)
| Reviewed by
Dr Anny Manrich (PhD)
The contents of this article are fact-based except otherwise stated within the article.
Author bio
Dr Rafael Frascino Cassaro PhD is a Chemist with expertise in Food Technology, extraction of essential oils from food sources, organocatalysis, extraction by supercritical CO2 and organic chemistry. He writes and reviews content on these topics.
Dr Rafael Frascino Cassaro’s Highlights:
- PIPE-FAPESP Project Coordinator for the company Bioativos Naturais Ltda involving the extraction of essential oils from food sources, with supercritical CO2.
- PhD in Chemistry with research in supercritical fluid reactivity.
- Bachelor of Environmental Chemistry at University of São Paulo State (UNESP)/Brazil
Professional Experience:
Dr Rafael Frascino Cassaro’s Experience:
Dr Rafael coordinated a PIPE-FAPESP Project (Company Research and Innovation Project) for the company Bioativos Naturais Ltda, involving the extraction of essential oils with supercritical CO2 from food sources such as turmeric, ginger, hops, orange bagasse, pepper rose, cupuaçu pie, among others.
Dr Rafael has worked on a project, involving studies of the influence of pre-treatment on the recovery of crude food extracts by extraction with supercritical CO2 (Supercritical Fluid Extraction or SFE) and with pressurized liquids (ethanol and water) for food sources, aimed at obtaining oleoresins; determination of global yield and chemical composition of crude extracts. As a postdoctoral fellow for the Food Engineering department at the University of Campinas/Brazil
Dr Rafael Frascino Cassaro has worked as a substitute Professor at the University of São Paulo State (UNESP) on General Chemistry and Thermodynamics II disciplines for the Food Engineering course.
Education:
- 2009 Bachelor in Environmental Chemistry at the State University of São Paulo, Brazil
- 2015 PhD in Chemistry with research in supercritical fluid reactivity University of São Paulo, Brazil
- 2017 Post Doctoral in Food Engineering Research: Influence of Biomass Pre-Treatment on Supercritical CO2 Extraction: Preservation of High Added Value Assets and Reduction of Process Costs at the State University of Campinas, Brazil
The main publications of Dr Rafael Frascino Cassaro are:
RC Bazito, RF CASSARO, LC OLIVEIRA, RA Gariani, CAO Nascimento. (2013). Proline derivatives as organocatalysts for the aldol reaction in conventional and non-conventional reaction media. Green Processing and Synthesis 2, 43-50
TS Bastos, SB Rodriguez Reartes, MS Zabaloy, RF Cassaro, RC Bazito. (2019).Phase Behavior for the System Carbon Dioxide plus p-Nitrobenzaldehyde: Experimental and Modeling JOURNAL OF CHEMICAL AND ENGINEERING DATA 64 (5), 2116-2125
GH Sakae, LM Takata, AS Paulino, RC Bazito, RF Cassaro, C Princival, .(2013). A high enantioselective Proline-based helical polymer catalyst for aldol type reaction. Blucher Chemistry Proceedings 1 (2), 214-214
You can view some of Dr Rafael’s work below and links to his professional profile.
Research Gate: https://www.researchgate.net/profile/Rafael-Cassaro-2
Fapesp: https://bv.fapesp.br/pt/pesquisador/680718/rafael-frascino-cassaro/
Google Scholar: https://scholar.google.com/citations?user=ToO7HIcAAAAJ&hl=en
Linkedin: https://www.linkedin.com/in/rafael-frascino-cassaro-4a156a37/?originalSubdomain=br
ORCID: https://orcid.org/0000-0002-3729-2858
Reviewer bio
Dr Anny Manrich PhD is a food Engineer with expertise in Food Technology, Natural Polymers, Edible Films, Enzymes, and Nanotechnology. She writes and reviews content on these topics.
Dr Anny Manrich’s Highlights:
- Research and Technology at the Brazilian Agricultural Research Corporation
- PhD in Chemical Engineering with a focus on Biochemistry at the Federal University of Sao Carlos/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
- Bachelor of Food Engineering at the University of Campinas/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
“To solve a problem, global vision and multifactorial understanding are necessary. Therefore, in addition to expertise, one should seek multidisciplinary thinking connected with science and reality” – Dr Anny Manrich, PhD.
Professional Experience:
Dr Anny Manrich’s Experience Joining the Brazilian Agricultural Research Corporation, as soon as she completed her doctorate,
Dr Anny Manrich has worked on several projects, including the more than three-year partnership project with BRF, a major food producer in Brazil. As a postdoctoral fellow.
Dr Anny Manrich has also contributed to several business consultancies and research projects of the National Nanotechnology Laboratory System in areas such as food technology, fibres, films and coatings and Nanotechnology; in a very determined way, having a great team relationship, being creative and committed.
Growing concerns about the safe introduction of nanomaterials into today’s life emphasises the need to create regulatory documentation in front of characterising, using and testing them. Dr Anny Manrich worked for two years on a characterization project for nanoscale materials, with the aim of exploring their possible health effects.
Despite not having specific academic training in packaging or polymeric films, Dr Anny Manrich works at the Brazilian Agricultural Research Corporation in areas of edible and biodegradable films produced from agricultural waste and in the development of films with greater resistance to water, having articles published in renowned scientific journals, which demonstrates her multidisciplinary understanding and creativity.
In addition, she worked for four years as a consultant to a food company to develop a line of snacks that are healthy and that add functional ingredients, physiologically active compounds that bring health benefits, made from fruits and vegetables, enabling diet improvement, disease prevention and reduction of nutritional deficiencies.
Dr Anny Manrich participated as a member of the examination board for two Master’s exams and one PhD exam at the Department of Chemical Engineering of the Federal University of São Carlos.
Education:
- 2001 Bachelor in Food Engineering at the State University of Campinas, Brazil
- 1999 One year scholarship at the Technical University of Munich
- 2004 Master in Chemical Engineering at the Federal University of São Carlos, Brazil
- 2012 PhD in Chemical Engineering at the Federal University of São Carlos, Brazil
- 2010 One year scholarship at the Technical University of Munich
The main publications of Dr. Anny Manrich are:
Articles
Manrich, A., Moreira, F. K., Otoni, C. G., Lorevice, M. V., Martins, M. A., & Mattoso, L. H. (2017). Hydrophobic edible films made up of tomato cutin and pectin. Carbohydrate Polymers, 164, 83-91.
Mendes, J. F., Norcino, L. B., Martins, H. H. A., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2020). Correlating emulsion characteristics with the properties of active starch films loaded with lemongrass essential oil. Food Hydrocolloids, 100, 105428.
Norcino, L. B., Mendes, J. F., Natarelli, C. V. L., Manrich, A., Oliveira, J. E., & Mattoso, L. H. C. (2020). Pectin films loaded with copaiba oil nanoemulsions for potential use as bio-based active packaging. Food Hydrocolloids, 106, 105862.
Manrich, Anny, et al. Immobilization of trypsin on chitosan gels: Use of different activation protocols and comparison with other supports. International Journal of Biological Macromolecules 43.1 (2008): 54-61.
Manrich, Anny; Komesu, Andrea ; Adriano, Wellington Sabino; Tardioli, Paulo Waldir ; Giordano, Raquel Lima Camargo . Immobilization and Stabilization of Xylanase by Multipoint Covalent Attachment on Agarose and on Chitosan Supports. Applied Biochemistry and Biotechnology, v. 161, p. 455-467, 2010.
Mendes, J. F., Martins, J. T., Manrich, A., Neto, A. S., Pinheiro, A. C. M., Mattoso, L. H. C., & Martins, M. A. (2019). Development and physical-chemical properties of pectin film reinforced with spent coffee grounds by continuous casting. Carbohydrate polymers, 210, 92-99..
Milessi, T. S., Kopp, W., Rojas, M. J., Manrich, A., Baptista-Neto, A., Tardioli, P. W., … & Giordano, R. L. (2016). Immobilization and stabilization of an endoxylanase from Bacillus subtilis (XynA) for xylooligosaccharides (XOs) production. Catalysis Today, 259, 130-139.
Mendes, J. F., Norcino, L. B., Manrich, A., Pinheiro, A. C. M., Oliveira, J. E., & Mattoso, L. H. C. (2020). Development, physical‐chemical properties, and photodegradation of pectin film reinforced with malt bagasse fibers by continuous casting. Journal of Applied Polymer Science, 137(39), 49178.
Mendes, J. F., Martins, J. T., Manrich, A., Luchesi, B. R., Dantas, A. P. S., Vanderlei, R. M., … & Martins, M. A. (2021). Thermo-physical and mechanical characteristics of composites based on high-density polyethylene (HDPE) e spent coffee grounds (SCG). Journal of Polymers and the Environment, 29, 2888-2900..
Mendes, J. F., Norcino, L. B., Martins, H. H., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2021). Development of quaternary nanocomposites made up of cassava starch, cocoa butter, lemongrass essential oil nanoemulsion, and brewery spent grain fibers. Journal of Food Science, 86(5), 1979-1996.
Manrich, A., Martins, M. A., & Mattoso, L. H. C. (2021). Manufacture and performance of peanut skin cellulose nanocrystals. Scientia Agricola, 79.
Nascimento, V. M., Manrich, A., Tardioli, P. W., de Campos Giordano, R., de Moraes Rocha, G. J., & Giordano, R. D. L. C. (2016). Alkaline pretreatment for practicable production of ethanol and xylooligosaccharides. Bioethanol, 2(1)..
Manrich, Anny, de Oliveira, J. E., Martins, M. A., & Mattoso, L. H. C. Physicochemical and Thermal Characterization of the Spirulina platensis. J. Agric. Sci. Technol. B, v. 10, p. 298-307, 2020.
Book Chapter
Terra, I. A. A., Aoki, P. H., Delezuk, J. A. D. M., Martins, M. A., Manrich, A., Silva, M. J., … & Miranda, P. B. (2022). Técnicas de Caracterização de Polímeros. Nanotecnologia Aplicada a Polímeros, 614.
Conference Papers
Ferreira, L. F., Luvizaro, L. B., Manrich, A., Martins, M. A., Júnior, M. G., & Dias, M. V. (2017). Comparação da estabilidade de suspensões poliméricas de amido/tocoferol e quitosana/tocoferol. In: CONGRESSO BRASILEIRO DE POLÍMEROS, 14., 2017, Águas de Lindóia, SP.
Manrich, A., Hubinger, S. Z., & Paris, E. C. (2017). Citotoxicidade causada por nanomateriais: avaliação do micronúcleo. In: WORKSHOP DA REDE DE NANOTECNOLOGIA APLICADA AO AGRONEGÓCIO, 9., 2017, São Carlos. Anais… São Carlos: Embrapa Instrumentação, 2017. p. 655-658.
Manrich, Anny, et al. Immobilization and Stabilization of Xylanase by multipoint covalent attachment on Glyoxyl Agarose Support. The 31st Symposium on Biotechnology for Fuels and Chemicals. 2009.
Manrich, Anny, et al. Application of immobilized xylanase on hydrolysis of soluble wood hemicelluloses after using microwave and organosolv pre-treatments. The 32nd Symposium on Biotechnology for Fuels and Chemicals. 2010.
You can view some of Dr Anny’s work below and links to her professional profile.
Research Gate: https://www.researchgate.net/profile/Anny-Manrich-2
Scopus: https://www.scopus.com/authid/detail.uri?authorId=23103497100
Google Scholar: https://scholar.google.com/citations?hl=en&user=Ea9qpr0AAAAJ
Linkedin: https://br.linkedin.com/in/anny-manrich-20693129
In this brief article, we will provide you with the answer to the question: “What is the pH of milk?”, discuss what is pH and the benefits of cow’s milk consumption.
What is the pH of milk?
Bovine milk (excluding mastitis and colostrum) exhibits a pH range of 6.6 to 6.8. Additionally, various physicochemical properties of milk, such as rennetability, ethanol stability, and heat stability, undergo fluctuations throughout the lactation period. (1)
Bovine milk primarily comprises water, constituting approximately 87% (w/w) of its composition. This aqueous component contains dissolved and suspended elements, serving as a vital source of hydration and nutrient supply for the neonate.
The pH of milk is a dynamic parameter, subject to constant changes during milk processing. These fluctuations can be attributed to factors like temperature variations, pressure adjustments, alterations in dry matter content, water removal, or microbial activity. (2)
What is pH?
pH represents the concentration of H+ ions, denoted as [H+], in an aqueous solution through a logarithmic expression. It offers a convenient way to express a wide range of [H+] values using small positive numbers. The letter “p” is used to signify the negative logarithm to the base10.
The pH scale extends from 0 to 14, encompassing hydrogen ion concentrations found in both dilute aqueous solutions and biological systems. A pH of 7 is considered neutral, which is characteristic of pure water.
When the pH value is less than 7, it indicates acidity, while a pH value greater than 7 signifies alkalinity or basicity. Due to its logarithmic nature, a change of one pH unit represents a tenfold difference in hydrogen ion concentration. (3)
What are the components of milk?
The composition of milk is subject to various influences, including the species of the animal, lactation stage, and genetics. Additionally, environmental conditions and the provided diet can also bring about changes in milk composition.
On average, milk is primarily composed of approximately 87% water, 4%-5% lactose, 3% protein, 3%-4% fat, 0.8% minerals, and 0.1% vitamins. When comparing milk from different species, cow milk stands out with the lowest fat content, second only to human milk in protein content. (4)
What factors affect milk pH?
The pH of milk is predominantly influenced by its amino acid profile, temperature, and mineral composition. While other milk components, such as lactose, lactose breakdown products, and microorganisms, also have an impact on milk pH, they are often considered as secondary or external factors.
To assess the overall influence of the milk ecosystem on pH, examining its buffering capacity is a useful approach.
Although minerals constitute a relatively small fraction of milk when compared to fat, protein, lactose, and water, they play a crucial role in stabilizing and configuring casein micelles. Consequently, they significantly affect the physicochemical and functional properties of dairy products. (2)
What are the Effects of Solids Content and Temperature on Milk pH?
The removal of water from milk systems causes a higher ratio of solute to solvent, leading to an increase in the ionic strength of the solution. This elevated ionic strength directly affects the hydrogen ion activity and, consequently, the pH.
During the evaporation process, the pH of milk decreases, and the ionic strength increases, resulting in a reduction in the activity coefficient of soluble calcium and phosphate.
Additionally, heat treatment often accompanies evaporation simultaneously, adding further complexity to consider when measuring the pH of milk concentrates. Therefore, multiple factors need to be taken into account to accurately assess the pH in such situations.
As the temperature of milk rises, the soluble contents of both calcium and phosphate decrease, and hydrogen ions are released simultaneously, leading to a decrease in pH. (2)
Can pH be used as a measure of milk spoilage ?
Yes, the pH of fresh milk is approximately 6.7, creating an environment suitable for the growth of various bacteria.
In the pH range of 4.0 – 5.0, lactic acid bacteria can thrive and produce lactic acid.
While these bacteria play a positive role in inhibiting the growth of harmful pathogens and are intentionally used in fermenting milk to produce dairy products like yogurt and cheese, they can also contribute to undesirable spoilage in specific circumstances.
As milk spoils, its acidity increases, making acidity a measurable indicator of milk quality. (5)
What happens if you consume spoiled milk?
Consuming spoiled milk can lead to food poisoning, manifesting as symptoms such as nausea, vomiting, diarrhea, abdominal cramps, fever, weakness, headaches, and dehydration.
Typically, a mild food poisoning episode lasts for approximately one to two days, while a more severe case may persist for up to 10 days. If the symptoms worsen or if diarrhea and vomiting persist for more than three days, seeking medical assistance is advisable. (6, 7)
Conclusion
In this brief article, we provided you with the answer to the question: “What is the pH of milk?”, discussed what is pH and the benefits of cow’s milk consumption.
References
- TSIOULPAS, A., LEWIS, M. J., & GRANDISON, A. S. A study of the pH of individual milk samples. International Journal of Dairy Technology, 60(2), 96–97. 2007.
- Aydogdu T, O’Mahony JA, McCarthy NA. pH, the Fundamentals for Milk and Dairy Processing: A Review. Dairy. 4(3):395-409. 2023.
- Blackstock, J. C. The physical chemistry of aqueous systems. Guide to Biochemistry, 11–19. 1989.
- Pereira, P. C., & Vicente, F. Milk Nutritive Role and Potential Benefits in Human Health. Nutrients in Dairy and Their Implications on Health and Disease, 161–176. 2017.
- M. Lu, Y. Shiau, J. Wong, R. Lin, H. Kravis, T. Blackmon, T. Pakzad, T. Jen, A. Cheng, J. Chang, E. Ong, N. Sarfaraz and N. Wang, Milk Spoilage: Methods and Practices of Detecting Milk Quality, Food and Nutrition Sciences, Vol. 4 No. 7A, 2013, pp. 113-123. 2013.
- Lu, M., & Wang, N. S. Spoilage of Milk and Dairy Products. The Microbiological Quality of Food, 151–178. 2017.
- Adda Bjarnadottir, Kelli McGrane, How Long Is Milk Good for After the Expiration Date? Them. Healthline Media LLC. 2020
