Comparative study among rheological, near-infrared light backscattering and confocal microscopy methodologies in enzymatic milk coagulation: Impact of different enzyme and protein concentrations

• All the methods were capable to evaluate the milk coagulation.
• Each method showed different responses in relation to formation and development of gel.
• Rheological method provided data concerning the gel consistency.
• NIR light backscattering scanning measured of the degree of bonding between the particles.
• Confocal microscopy allowed for visualization of the formation of the protein network.

Enzymatic milk coagulation affects parameters such as yield, moisture content and texture and various methodologies have been used to evaluate this process. Thus, the present work comparatively evaluated milk coagulation with different enzyme (10.00, 16.67 and 23.33 IMCU.L−1 milk) and protein (1.5, 3.0 and 6.0%) concentrations using rheological methods, near-infrared (NIR) light backscattering and confocal microscopy. The enzymatic hydrolysis (first phase of coagulation) can be explained by the parameters determined in the NIR light backscatter profile. All the methodologies were capable of describing the protein network aggregation process (second phase of coagulation), and using the rheological trials and NIR light backscattering, the gels with greater enzyme or protein concentrations were shown to have more protein aggregation, resulting in more consistent gels. In addition the start of aggregation could be measured and the formation of the gel microstructure visually accompanied by confocal microscopy. Thus, all the methods could be used to make an overall evaluation of the milk coagulation phenomenon, but the method should be chosen according to the parameters one desires to use to compare the different samples.

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