Measuring Internal Maturity Parameters Contactless on Intact Table Grape Bunches Using NIR Spectroscopy.

Area of Science:

• Agricultural Science
• Spectroscopy
• Food Science

Background:

• Traditional methods for determining table grape maturity (total soluble solids, titratable acidity) are destructive and time-consuming.
• Accurate and efficient assessment of grape maturity is crucial for harvest timing and quality control.

Purpose of the Study:

• To investigate the feasibility of using Fourier Transform Near-Infrared (FT-NIR) spectroscopy for non-destructive determination of internal maturity parameters in intact table grape bunches.
• To develop predictive models for key attributes like total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, pH, and BrimA.

Main Methods:

• Contactless FT-NIR spectroscopy was employed on intact table grape bunches across two harvest seasons.
• Partial Least Squares (PLS) regression models were built to correlate spectral data with manually determined fruit quality parameters.
• Various spectral pre-processing techniques (MSC, SNV, SG1d) were evaluated for model optimization.

Main Results:

• Predictive models demonstrated varying degrees of success, with the prediction correlation coefficient (R²p) ranging from 0.28 (pH) to 0.77 (BrimA).
• The best performance for TSS was achieved using Moving Smoothing Windows (MSW) + Multiplicative Scatter Correction (MSC).
• Titratable acidity (TA) models improved with Standard Normal Variate (SNV) pre-processing.

Conclusions:

• FT-NIR spectroscopy shows promise for the non-destructive, contactless assessment of table grape internal quality parameters.
• This technology can potentially streamline quality control processes in the grape industry.
• Further research and model refinement are needed for widespread practical application.