Time-resolved reflectance spectroscopy as a management tool for late-maturing nectarine supply chain

The absorption coefficient of the fruit flesh at 670 nm (mu(a)), measured at harvest by time-resolved reflectance spectroscopy (TRS) is a good maturity index for early nectarine cultivars. A kinetic model has been developed linking the mu(a), expressed as the biological shift factor to softening during ripening. This allows shelf life prediction for individual fruit from the value of mu(a) at harvest and the fruit categorization into predicted softening and usability classes. In this work, the predictive capacity of a kinetic model developed using mu(a) data at harvest and firmness data within 1-2 d after harvest for a late maturing nectarine cultivar ('Morsiani 90') was tested for prediction and classification ability. Compared to early maturing cultivars, mu(a) at harvest had low values and low variability, indicating advanced maturity, whereas firmness was similar. Hence, fruit were categorized into six usability classes (from 'transportable-hard' to 'ready-to-eat-very soft') basing on mu(a) limits established analyzing firmness data in shelf life after harvest. The model was tested by comparing the predicted firmness and class of usability to the actual ones measured during ripening and its performance compared to that of models based on data during the whole shelf life at 20 degrees C after harvest and after storage at 0 degrees C and 4 degrees C. The model showed a classification ability very close to that of models based on data of the whole shelf life, and was able to correctly segregate the 'ready-to-eat-transportable', 'transportable' and 'transportable-hard' classes for ripening at harvest and after storage at 0 degrees C, and the 'ready-to-eat-very soft' and 'ready-to-eat-soft' classes for ripening after storage at 4 degrees C, with lower performance of models for fruit after storage at 4 degrees C respect to those of the other two ripening

Quality characteristics of air-dried apple rings: Influence of storage time and fruit maturity measured by time-resolved reflectance spectroscopy

AbstractWith the aim of studying the influence of maturity and of cold storage time on the quality characteristics of air-dried apple rings, 60 apples (cv Pink Lady®) were measured at harvest by time-resolved reflectance spectroscopy (TRS) at 670nm, ranked on the basis of decreasing absorption coefficient at 670nm (μa670, increasing maturity) and hence classified based on the ranking order as less mature (LeM), medium mature (MeM,) and more mature (MoM). The sixty fruit were, then, randomized into 3 batches corresponding to 3 storage times (0, 3 and 5 months in normal atmosphere at +1°C), and, at each storage time, 3 rings/fruit were air-dried at 80°C up to a constant weight using a pilot air circulated drier. Quality characteristics of fresh fruit and of air-dried rings were analysed by ANOVA and PCA statistical analyses. Stored fruit compared to fruit at 0m were softer, had lower stiffness and energy-to-rupture, and higher soluble solids content (SSC), relative intercellular space volume (RISV) and L*f. LeM class had lower SSC and dry matter, and the MoM class higher a*f and lower b*f than the other two classes. 3m-Apples showed the highest differences with respect to fresh ring in browning index (BI), total colour, chroma and hue, compared to fruit processed at 0m and 5m. Air-dried rings from less mature apples (i.e. those processed at 0m and of LeM class) had higher Fmax, Emod, E and BI than those from more mature fruits (i.e. those processed after storage and of MoM class). PCA underlined the positive relationship between mechanical characteristics of fresh fruit with those of dried rings and ring shrinkage, which were opposite to RISV, SSC and weight loss

Electronic Nose To Detect Volatile Compound Profile and Quality Changes in 'Spring Belle' Peach (Prunus persica L.) during Cold Storage in Relation to Fruit Optical Properties Measured by Time-Resolved Reflectance Spectroscopy

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Studies on classification models to discriminate ‘Braeburn’ apples affected by internal browning using the optical properties measured by time-resolved reflectance spectroscopy

This work aimed at studying the feasibility of time-resolved reflectance spectroscopy (TRS) to nondestructively detect internal browning (IB) in ‘Braeburn’ apples through the development of classification models based on absorption (ua) and scattering (us') properties of the pulp.This research was carried out in two seasons: in 2009, apples were measured by TRS at 670 nm and inthe 740–1040 nm spectral range on four equidistant points around the equator, whereas in 2010 appleswere measured by TRS at 670 nm and at 780 nm on eight equidistant points. The values of the absorption coefficients measured in the 670–940 nm range increased with IB devel-opment. On the contrary, us'780 was higher in healthy fruit than in IB ones. The ua780 also significantlyincreased with IB severity, showing high values when IB affected the pulp tissues compared to the coreones. Also ua670 changed with IB development, but it was not able to clearly discriminate healthy fruitfrom IB ones because its value was also affected by the chlorophyll content of the pulp. The absorption and scattering coefficients were used as explanatory variables in the linear discriminant analysis in order to classify each apple tissue as healthy or IB; then the models obtained were used forfruit classification. The best classification performance was obtained in 2010 using ua780 and us'780and considering the IB position within the fruit: 90% of healthy fruit and 71% of IB fruit were correctly classified. By using all the ua measured in the 670–1040 nm range plus the us'780, IB fruit classification was slightly better while healthy fruit classification was worse. The better result of 2010 was due tothe increased number of TRS measurement points that allowed better exploration of the fruit tissues. However, the asymmetric nature of this disorder makes detection difficult, especially when the disorderis localized in the inner part of the fruit (core) or when it occurs in spots. A different TRS set-up (position and distance of fibers, time resolution) should be studied in order to reach the deeper tissue within the fruit in order to improve browning detection

Influence of edible coating on postharvest physiology ana quality of honeydew melon fruit (Cucumis melo L. inodorus)

Several techniques have been developed to preserve the quality of horticultural products throughout the supply chain. Edible coatings represent a promising technology as they can improve quality and extend shelf life of fruit and vegetables by changing gases and moisture permeabilties, enhancing fruit appearance, and reducing microbial contamination.The aim of this work was to assess the effectiveness of two kinds of novel coatings on the shelf life extension of Honeydew winter melons during retail. Sixty melons were used: 24 were uncoated as control; 18 were treated with a cellulose polymer coating (F1) and 18 with a synthetic polymer (F2) coating. Upon arrival, and after 6, 9 and 13 days at 13°C, six melons/treatment were individually analyzed for internal O2, ethylene and ethane concentrations, fermentative metabolites, quality parameters, and aroma pattern. Already after six days, internal O2 levels in coated fruit fell to ~1% in F1 and ~3% in F2 melons, triggering fermentative pathways as shown by the increased productions, mainly in F1 fruit, of acetaldehyde, ethanol, ethyl acetate, and ethane. This pattern caused changes in the responses of electronic nose sensors which were able to distinguish the three treatments. Coating did not influence fruit firmness and internal ethylene concentration. F1 coating reduced soluble solids content, strongly enhanced skin glossiness, and delayed yellowing, but it was not able to prevent moisture losses. In contrast, F2 coating significantly reduced weight loss and showed a slight positive effect on fruit appearance

Quality and nutraceutical properties of mango fruit: influence of cultivar and biological age assessed by Time‐resolved Reflectance Spectroscopy

The content and composition of the main antioxidants in the pulp of mangoes depend also on cultivar and maturity degree, the latter being non-destructively evaluated by the absorption coefficient measured by Time-resolved Reflectance Spectroscopy (TRS) at 540 nm (µa540). Aiming at evaluating the levels of antioxidants [carotenoids (CAR), phenols (TPC), ascorbic acid (AA)] and antioxidant capacity (TAC) in relation to µa540 maturity class, selected ‘Haden’ and ‘Palmer’ mangoes were measured for µa540 by TRS, classified based on µa540 value as less (LeM), medium (MeM) and more (MoM) mature and analyzed for pulp firmness, pulp color (a*, h°, Yellowness Index), CAR (total and composition by HPLC-DAD), TPC, AA and TAC. ‘Palmer’ fruit had higher TPC, AA and TAC than ‘Haden’ mangoes. On average MoM fruit showed higher TPC, total CAR, total all‐trans‐violaxanthin esters and all‐trans‐β‐carotene than MeM and LeM fruit. LeM fruit did not have compounds belonging to the 9‐cis‐violaxanthin group, while cis‐β‐cryptoxanthin was approx. 19% of total carotenoids. In MoM mangoes the main carotenoid was all‐trans‐β-carotene (53%), followed by total all‐trans‐violaxanthin esters (30%), 9‐cis‐violaxanthin group (8%) and cis‐β‐cryptoxanthin (6%). The µa540 significantly correlated (r=0.78‐0.94) with total CAR, all‐trans‐β‐carotene, all‐trans‐violaxanthin no.3 (both cultivars), TPC, all‐trans‐violaxanthin no.1, no.2, no.6 (‘Haden’), and 9‐cis‐violaxanthin no.2, no.3 (‘Palmer’). Our results indicate that TRS is suitable to non-destructively measure the pulp color of mangoes and to sort fruit with different ripening degree and nutraceutical properties

Optical properties, ethylene production and softening in mango fruit

Firmness decay, chlorophyll breakdown and carotenoid accumulation, controlled by ethylene, are major ripening events in mango fruit. Pigment content and tissue structure affect the optical properties of the mesocarp, which can be measured nondestructively in the intact fruit by time-resolved reflectance spectroscopy (TRS). This work is aimed at improving the maturity assessment in mango ( Mangifera indica L. cv Haden) from Brazil, using TRS absorption in both the carotenoid and chlorophyll regions in order to develop a model for fruit ripening. Scattering and absorption in the 540-900. nm spectral range by TRS, ethylene production and respiration rate, and firmness, were measured in one day on each individual fruit of a sample covering the range of maturity. The fruit displayed a variability which was attributed to the different biological age. Absorption spectra showed two peaks at 540 and 670. nm, corresponding respectively to the tail of carotenoid absorption and to chlorophyll- a absorption. Carotenoids increased substantially only in fruit where chlorophyll had almost disappeared. The absorptions at 540 and 670. nm, which described the maturity state of each fruit relative to the range of each wavelength, were combined in one index of biological age (biological shift factor) for each fruit and used in logistic models of ethylene increase and firmness decay respectively. The model explained about 80% of the variability in ethylene production rate. A similar result was obtained for firmness when scattering was added in the model. The combination of absorption at 540 and 670. nm measured by TRS in the intact fruit can be used to classify mango fruit according to maturity and to predict the ripening of individual fruit

Water spectral pattern as a marker for studying apple sensory texture

Aquaphotomics is a scientific discipline which investigates the water-light interactions in biological systems by using NIR spectroscopy and multivariate analysis to relate water absorption patterns to bio-functionalities. This work aimed at evaluating the feasibility of Aquaphotomics to study apple fruit sensory texture. ‘Braeburn’, ‘Gala’ and ‘Kanzi®’ apples were analyzed by a MicroNIR spectrometer and for mechanical, structural and texture sensory characteristics. Cluster analysis on sensory texture attributes showed four different profiles for each cultivar having different water spectral patterns (WASP). On average, the WASP of mealy apples showed the highest absorbance values at 1364, 1372 and 1382 nm and the lowest in the 1438-1492 nm range suggesting a preponderance of water structures with weak-hydrogen bonds; the opposite was found in crispy and juicy apples indicating the presence of more organized water structures with medium-strong hydrogen bonds. This WASP difference could be due to a different softening rate: apples clustered as firm/crispy/juicy had the highest firmness and the lowest intercellular spaces, while mealy apples had low firmness and high intercellular spaces indicating a more advanced softening. The chemical changes due to the pectin hydrolyzation could affect the water structures. The Aquaphotomics approach could be a useful tool for studying the sensory texture of fruits as water structures actually change in apples with different textural characteristics whatever the cultivars