Acid-induced coagulation

The excitation fluorescence spectra of vitamin A located in the fat globules of milk showed a maximum of 322 nm and two shoulders at 309 and 296 nm. As shown in Fig. 11, the shape of the spectra changes during the kinetics of acid-induced milk coagulation. Between 0 and 300 min, the shapes of the spectra are characterized by a decrease of the intensities at 322 nm and 310 nm and an increase of the intensity at 296 nm. These changes indicate that the environment of the fluorescent probe is modified during acid-induced coagulation of milk. 

Self-diffusion during acid-induced coagulation. 

V. FLUORESCENCE SPECTROSCOPY INVESTIGATION OF ACID- OR RENNET-INDUCED COAGULATION OF MILK... 

Investigation of Protein-Lipid Interaction Development During Acid-Induced Milk Coagulation Kinetics... 

Heat, strong acids or bases, ethanol, or heavy-metal ions irreversibly alter the secondary structure of proteins (see below). This process, known as denaturation, is exemplified by the heat-induced coagulation and hardening of egg white (albumin). Denaturation destroys the physiological activity of proteins. 

Chemical ablation is classified based on the used agent, such as ethanol, or acetic acid. By definition, chemical ablation induces coagulation necrosis and tumor ablation. Ethanol ablation is also called percutaneous ethanol instillation (PEI), percu-... 

Trichloroacetic Acid (TCA) causes precipitation of proteins and coagulative necrosis of epidermal cells [4]. The extent of damage is indeed concentration dependent. Concentrations range from 10 to 50%. Superficial TCA peeling is induced by concentrations of 10-30% whereas higher concentrations cause medium depth or deep peeling. The combination of salicylic acid followed by TCA 10-15% induces superficial wounding. 

Oversaturation is induced by adjusting the pH of incipiently acidic Fe(III) and AI(III) solutions. After initiation of the oversaturation, the hydrolysis of AI(III) and Fe(III) progresses and charged multimeric hydroxo AI(III) and Fe(III) species, the actual coagulants, are formed as intermediates ultimately these intermediates polymerize to solid Al (III) and Fe(III)(hydr)oxides, respectively. 

Decrease in pH. After heating at 140°C for 20 min, the pH of milk has decreased to about 5.8 due to acid production from pyrolysis of lactose, precipitation of soluble calcium phosphate as Ca3(P04)2, with the release of H+, and dephosphorylation of casein with subsequent precipitation of the liberated phosphate as Ca3(P04)2 with the release of H+. The heat-induced precipitation of Ca3(P04)2 is partially reversible on cooling so that the actual pH of milk at 140°C at the point of coagulation is much lower than the measured value and is probably below 5.0. 

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