[Relationship between different milk processing and near infrared spectra].

Area of Science:

• Food Science
• Analytical Chemistry
• Spectroscopy

Background:

• Milk processing techniques like homogenization and pasteurization alter milk composition and structure.
• Understanding these alterations is crucial for effective milk quality control.
• Near-Infrared Spectroscopy (NIRS) is a rapid, non-destructive analytical technique with potential for milk analysis.

Purpose of the Study:

• To investigate the impact of milk processing on Near-Infrared (NIR) spectra.
• To establish the theoretical basis for using NIRS in milk quality control.
• To develop a method for identifying reconstituted milk in pasteurized milk.

Main Methods:

• Analysis of NIR spectra of raw and processed milk (homogenized, pasteurized).
• Examination of spectral changes in the 1890 nm region.
• Development of a chemometric model (SIMCA) for milk discrimination.
• Application of spectral pretreatment methods (second derivative, Norris 5.5).

Main Results:

• Significant spectral differences were observed between raw and processed milk, particularly around 1890 nm.
• Homogenization led to a sharp decrease in absorbance, while pasteurization caused an increase.
• A discriminant analysis model achieved 98.1% accuracy in identifying reconstituted milk within pasteurized milk samples.
• Changes in fat globule structure due to processing were identified as a key factor influencing spectral changes.

Conclusions:

• NIRS can effectively distinguish between raw and processed milk based on spectral signatures.
• The study provides a theoretical framework for NIRS application in milk quality assessment.
• Accurate identification of reconstituted milk is achievable using NIRS and chemometric methods.