Articles
Physiological changes affect mechanical-acoustic properties of ready-to-eat rocket packed in different atmospheres
Article number
1442_3
Pages
17 – 26
Language
English
Abstract
Texture, together with appearance, flavor, and nutritional value, is a critical quality attribute of fresh-cut vegetables, as consumers generally prefer crispy and fresh products.
Texture depends on leaf anatomy, turgor and cell wall composition, which determine the breaking behavior of the tissues and the consequent sound propagation.
To increase knowledge about the texture of leafy vegetables, in this study the mechanical and acoustic properties of ready-to-eat rocket leaves were related to physiological changes occurring during shelf-life in different atmospheres.
Fresh-cut rocket leaves were packed in air (A) and under two modified atmospheres: 5% O2 + 10% CO2 + 85% N2 (C) or 30% O2 + 70% N2 (O). After 1, 4, 7, 11 and 13 days of storage shelf-life at 4°C, rocket leaves were analyzed for mechanical-acoustic properties, water content, color (L*, h°), maximal photochemical efficiency (Fv/Fm), chlorophyll content and electrolyte leakage.
From the mechanical/acoustic profile, 8 parameters were extracted: firmness, rigidity index, work, break distance, Nsounds, Nsounds>50dB, dBmax and dBbreak. Principal component analysis on mechanical-acoustic parameters extracted two functions explaining 70% of the variability.
The PC1 grouped mechanical attributes, showing the highest scores at day 13 and the lowest in C; PC2 grouped acoustic parameters and its scores increased during storage, showing the highest values in C. The Fv/Fm decreased throughout 13 days, mainly in C treatment, which showed the lowest values while chlorophyll content decreased regardless of the atmosphere.
An opposite trend was observed for electrolyte leakage, which was negatively related to Fv/Fm.
The latter was also negatively related to PC2 scores and CO2 level, while chlorophyll content was positively related to h° and negatively to PC2 scores.
L* increased during shelf-life in C and in O, reaching the highest values in C. Our results indicate that alterations in the physiological status of fresh-cut rocket salad affected the structural integrity of the leaves, as evidenced by changes in mechanical-acoustic parameters.
Texture depends on leaf anatomy, turgor and cell wall composition, which determine the breaking behavior of the tissues and the consequent sound propagation.
To increase knowledge about the texture of leafy vegetables, in this study the mechanical and acoustic properties of ready-to-eat rocket leaves were related to physiological changes occurring during shelf-life in different atmospheres.
Fresh-cut rocket leaves were packed in air (A) and under two modified atmospheres: 5% O2 + 10% CO2 + 85% N2 (C) or 30% O2 + 70% N2 (O). After 1, 4, 7, 11 and 13 days of storage shelf-life at 4°C, rocket leaves were analyzed for mechanical-acoustic properties, water content, color (L*, h°), maximal photochemical efficiency (Fv/Fm), chlorophyll content and electrolyte leakage.
From the mechanical/acoustic profile, 8 parameters were extracted: firmness, rigidity index, work, break distance, Nsounds, Nsounds>50dB, dBmax and dBbreak. Principal component analysis on mechanical-acoustic parameters extracted two functions explaining 70% of the variability.
The PC1 grouped mechanical attributes, showing the highest scores at day 13 and the lowest in C; PC2 grouped acoustic parameters and its scores increased during storage, showing the highest values in C. The Fv/Fm decreased throughout 13 days, mainly in C treatment, which showed the lowest values while chlorophyll content decreased regardless of the atmosphere.
An opposite trend was observed for electrolyte leakage, which was negatively related to Fv/Fm.
The latter was also negatively related to PC2 scores and CO2 level, while chlorophyll content was positively related to h° and negatively to PC2 scores.
L* increased during shelf-life in C and in O, reaching the highest values in C. Our results indicate that alterations in the physiological status of fresh-cut rocket salad affected the structural integrity of the leaves, as evidenced by changes in mechanical-acoustic parameters.
Authors
M. Vanoli, M. Buccheri, V. Picchi, F. Lovati, A. Calzone, T.M.P. Cattaneo, G. Cortellino
Keywords
chlorophyll fluorescence, electrolyte leakage, texture, MAP, color
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