Investigation of the packaging influence in the visible-near infrared analysis of fresh-cut Valerianella locusta L. leaf and Golden Delicious apple

Monitoring the quality decay of fresh-cut products is necessary to control the freshness level during the entire production chain and to ensure quality product for the consumer. The aim of this work was to investigate the capability of vis/NIR and NIR spectroscopy to perform useful optical measurements not only directly on the samples but even from the outside of the pack through the packaging film on fresh-cut Valerianella leaves and fresh-cut Golden Delicious apple slices. The use of two spectrophotometers in contiguous spectral ranges allows to explore a broad spectral range and to compare relatively low-cost spectrophotometers, with the final aim to identify the most suitable to achieve the goal of the study. Principal component analysis and partial least square discriminant analysis were applied on spectral data, and the expiration date was chosen as the freshness threshold to reach the objective. Results on Golden Delicious could be considered satisfactory even if the classification performances were lower than those obtained for Valerianella; however, overall collected positive predictive values ranged from 86.7 % to 100.0 %. The presence of packaging had only a slight effect on classification capability. These findings would be useful in the development of freshness decay assessment tools using these optical techniques along products’ post-packaging chain. The future availability of a non-destructive instrument allowing the evaluation of changes during the shelf life or estimating the quality parameters could have a wide range of practical applications in the post-packaging chain: during the storage period before packaging, during the production process for identifying critical points, and during the distribution chain, the most critical phase. Furthermore, the possibility to implement non-destructive technology for monitoring the product freshness at the point of sale should be a guarantee for consumers.