engleski

Applicability of near-infrared spectroscopy in the analysis of macronutrient contents of grape pomace and grape pomace mixtures

Grape pomace is a by-product of the wine making process which is usually produced in great tonnages after wine production. Its large quantity represents a great environmental risk so the researchers are looking for ways to re-use the pomace in different processes such as composting, animal feed, polyphenol extraction or seed oil production. Among the possible uses of grape pomace is its use in food products. Up till now, there are examples of its use in food products, but mostly as extracts. However, it is important to explore its use “as is” in food products, as well as the possibilities of its macronutrient analysis using fast, non-destructive techniques such as near infrared spectroscopy (NIRs). Therefore, the aim of this paper was to produce mixtures of grape pomace with different contents of macronutrients and record the NIR spectra of the produced mixtures. Produced mixtures differed in the carbohydrate, fat, sugar, fiber and salt content and the differences in the macronutrient content were connected to the NIR spectra of the samples using multivariate analysis – principal component analysis (PCA), partial least squares (PLS) regression and artificial neural networks (ANN). The results showed good applicability of PCA analysis and ANNs in differentiating between macronutrient contents of grape pomace mixtures. However, PLS method showed very low R2 values, as well as high root mean squared error (RMSE) values, making it not suitable for the use in pomace analysis.

grape pomace ; food waste ; near infrared spectroscopy ; macronutrients ; multivariate analysis

The work was supported by the European Union through the European regional development fund, Competitiveness and Cohesion 2014–2020 (KK.01.1.1.07.0007.)