PH, of food

The food industry uses the acetic acid/sodium acetate buffer to control the pH of food. Given the following mixtures of acetic acid, HC2H302 (HAc), and sodium hydroxide, show by calculation which of the following solutions is a buffer. 

Nowadays, the importance of pH is considered with respect to many aspects of our lives. Its influence on the health and well-being is often mentioned in a sense of body s internal environment, for example, the impact of pH of food on the digestive system. However, concerns about pH deal not only with the inside of the body, but also with its most external organ, the skin. 

Now you understand what manufacturers of shampoos and antacids mean when they say that their products are buffered the products have ingredients that resist pH changes. The pH of foods affects their taste and texture, so many packaged foods are buffered, too. Check ingredient labels for phosphates. The presence of phosphates probably means that the product contains the acid-base pair H2P04/HP04 to control the pH. 

Occurs in the free state in lemons, currants, beetroot etc. and the seeds and juices of many flowers and plants. Constit. of fruit drinks, pharmaceutical syrups, for adjusting pH of foods etc. Component of anticoagulant citrate solns. Used as masking agent for many polyvalent metals and as a component of buffers. Commercially available. Cryst. + IH2O (H2O), losing H2O at 70-5°. V. sol. H2O, EtOH, mod. sol. Et20. Mp 135° (monohydrate), Mp 153° (anhydrous). p/C j 3.13 4.78 pA ,3 6.43 (25°). 

The carcinogenicity of nitrosamines has created widespread concern over the safety of food products that are significant sources of nitrates and nitrites. Nitrosamines are readily formed by reaction of secondary amines with nitrites at acid pH, conditions which may occur in the gastrointestinal tract. 

Aluminum chlorohydrate [12359-72-7] Al2(OH) Gl 2H20 is a PAG product of specific composition, having r = 2.5. Aluminum chlorohydrate is used in antiperspirants regulated by the U.S. Food and Dmg Administration (FDA). Solutions sold for FDA-approved use are colorless in appearance, have 23—24% Al as AI2O2, and low levels of iron (<50 ppm), sulfate (<0.025 %), metals (Ga, Mg, Na <10 ppm), and heavy metals (as Pb <10 ppm). The pH of these solutions at 25°G is about 3.8—4.0. Typically, solutions at 25°G have specific gravities from 1.33 to 1.35 and viscosities from 40 to 60 mPa-s(=cps). Aluminum chlorohydrate [12042-91 -0] is also available in dry form with different particle-size distributions. 

The FDA is headed by the Commissioner of Food and Dmgs. This position is not a Cabiaet-level office but falls within the PubHc Health Service (PHS), a division within the U.S. Department of Health and Human Services (HHS). The post of FDA Commissioner is subject to HHS pohtical clearance and Senate confirmation, and the Commissioner is ultimately accountable to HHS, Congress, and the President of the United States. The Commissioner has a staff to assist ia poHcy making and several deputy commissioners to oversee operation of ah. the subordinate units. FDA has six regional offices within the country, each responsible for a section of the country, and 21 district offices. Persons with technical background typicahy work ia one of FDA s chemistry laboratories or as investigators or consumer safety officers. 

The effect of various pHs has been well known for some time. Acidic foods such as fmits tend to retard microbial growth and resist certain types of contamination. For this reason, the standards adopted industry-wide have been based on the processing of foods of high acidity (low pH). In the United States, the FDA has regulatory responsibiUty over the preparation, sterilization, and distribution of foods. 

Citric acid is utilized in a large variety of food and industrial appHcations because of its unique combination of properties. It is used as an acid to adjust pH, a buffer to control or maintain pH, a chelator to form stable complexes with multivalent metal ions, and a dispersing agent to stabilize emulsions and other multiphase systems (see Dispersants). In addition, it has a pleasant, clean, tart taste making it useful in food and beverage products. 

About 50% of copper in food is absorbed, usually under equitibrium conditions, and stored in the tiver and muscles. Excretion is mainly via the bile, and only a few percent of the absorbed amount is found in urine. The excretion of copper from the human body is influenced by molybdenum. A low molybdenum concentration in the diet causes a low excretion of copper, and a high intake results in a considerable increase in copper excretion (68). This copper—molybdenum relationship appears to correlate with copper deficiency symptoms in cattle. It has been suggested that, at the pH of the intestine, copper and molybdate ions react to form biologically unavailable copper molybdate (69). 

The Role of Alum in Historical Papermaking. .. and other Polyvalent Metals on the Viscosity of Gelatin Solutions. Journal of the Science of Food. .. WF et al. "The Effect of Alum and pH on Sheet Acidity , go to the following web site http //palimpsest.stanford.edu... 

Bacterial catabolism of oral food residue is probably responsible for a higher [NHj] in the oral cavity than in the rest of the respiratory tract.Ammonia, the by-product of oral bacterial protein catabolism and subsequent ureolysis, desorbs from the fluid lining the oral cavity to the airstream.. Saliva, gingival crevicular fluids, and dental plaque supply urea to oral bacteria and may themselves be sites of bacterial NH3 production, based on the presence of urease in each of these materials.Consequently, oral cavity fNTi3)4 is controlled by factors that influence bacterial protein catabolism and ureolysis. Such factors may include the pH of the surface lining fluid, bacterial nutrient sources (food residue on teeth or on buccal surfaces), saliva production, saliva pH, and the effects of oral surface temperature on bacterial metabolism and wall blood flow. The role of teeth, as structures that facilitate bacterial colonization and food entrapment, in augmenting [NH3J4 is unknown. 

Self-Test 10.5B The pH of pancreatic fluids, which help to digest food once it has left the stomach, is about 8.2. What is the approximate concentration of H30+ ions in pancreatic fluids ... 

MITCHELL J H, CAWOOD E, KINNIBURGH D, PROVAN A, COLLINS A R, IRVINE D S (2001) Effect of a ph)doestrogen food supplement on reproductive health in normal males. Clin Sci. 100 613 18. 

The formation of nitrosamines in aprotic solvents has applicability to many practical lipophilic systems including foods (particularly bacon), cigarette smoke, cosmetics, and some drugs. The very rapid kinetics of nitrosation reactions in lipid solution indicates that the lipid phase of emulsions or analogous multiphase systems can act as "catalyst" to facilitate nitrosation reactions that may be far slower in purely aqueous media (41, 53, 54). This is apparently true in some cosmetic emulsion systems and may have important applicability to nitrosation reactions in vivo, particularly in the GI tract. In these multiphase systems, the pH of the aqueous phase may be poor for nitrosation in aqueous media (e.g., neutral or alkaline pH) because of the very small concentration of HONO or that can exist at these pH ranges. 

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