1,721,389 research outputs found
Approach for non-destructive pigment analysis in model liquids and carrots by means of time-of-flight and multi-wavelength remittance readings
No full textOptical properties of developing pip and stone fruit reveal underlying structural changes
Full text linkAnalyzing the optical properties of fruits represents a powerful approach for non-destructive observations of fruit development. With classical spectroscopy in the visible and near-infrared wavelength ranges, the apparent attenuation of light results from its absorption or scattering. In horticultural applications, frequently, the normalized difference vegetation index (NDVI) is employed to reduce the effects of varying scattering properties on the apparent signal. However, this simple approach appears to be limited. In the laboratory, with time-resolved reflectance spectroscopy, the absorption coefficient, μa, and the reduced scattering coefficient, μs′, can be analyzed separately. In this study, these differentiated optical properties were recorded (540-940 nm), probing fruit tissue from the skin up to 2 cm depth in apple (Malus × domestica 'Elstar') and plum (Prunus domestica 'Tophit plus') harvested four times (65-145 days after full bloom). The μa spectra showed typical peak at 670 nm of the chlorophyll absorption. The μs′ at 670 nm in apple changed by 14.7% (18.2-15.5 cm-1), while in plum differences of 41.5% (8.5-5.0 cm-1) were found. The scattering power, the relative change of μs′, was zero in apple, but enhanced in plum over the fruit development period. This mirrors more isotropic and constant structures in apple compared with plum. For horticultural applications, the larger variability in scattering properties of plum explains the discrepancy between commercially assessed NDVI values or similar indices and the absolute μa values in plum (R < 0.05), while the NDVI approach appeared reasonable in apple (R ≥ 0.80)
Carotenoid content and pulp colour non-destructively measured by time-resolved reflectance spectroscopy in different cultivars of Brazilian mangoes
No full textCarotenoid biosynthesis is one of the most important biochemical changes occurring during mango ripening. Carotenoids are responsible for the yellow-orange pulp colour, which is one of the best maturity indices for mangoes, notwithstanding it is a destructive method. Time-resolved reflectance spectroscopy (TRS) is a nondestructive technique which simultaneously quantifies the internal optical properties of fruit related to pigments (absorption coefficient, μa) and to structure (reduced scattering coefficient, μs') by probing the pulp to a depth of 1-2 cm with no or limited influence from the skin. In previous works, it was found that TRS is able to predict with good accuracy the pulp colour of mangoes and then to sort fruit with different maturity degrees. The aim of this research was to study the relationships among TRS optical properties, total carotenoids content and pulp colour parameters of two cultivars of Brazilian mangoes transported by plane to Italy. Fruit were measured by TRS in the 540-690 nm range for 'Palmer' cultivar and in the 540-780 nm range for 'Haden' and analyzed for pulp colour and total carotenoids content. Total carotenoids ranged from 5.2 to 32.7 mg kg-1 FW for 'Palmer' and from 5.9 to 56.2 mg kg-1 FW for 'Haden'. By using partial least squares regression, good correlations were obtained between TRS absorption spectra and total carotenoids content (R2cv=0.83 and 0.93 for 'Haden' and 'Palmer', respectively) and pulp colour parameters (R2cv=0.78-0.96)
Sensory profiles of various stored fruit species are affected by maturity class assessed by time-resolved reflectance spectroscopy at harvest
Full text linkThe absorption coefficient measured at harvest at 670 nm (μa670) by timeresolved reflectance spectroscopy (TRS) is a non-destructive maturity index used to evaluate the biological age of fruit, i.e., the fruit maturity stage. The μa670 was successfully used to classify nectarine, apple and mango fruit into maturity classes each one having distinctive ripening behaviors. Aiming at studying the influence of TRS maturity class assessed at harvest on the sensory profiles of various fruit species after storage, 'Jonagored' apples, 'Abbé Fétel' pears, 'Morsiani 90' nectarines and 'Spring Belle' peaches were measured at harvest by TRS at 670 nm, ranked on the basis of decreasing μa670 (increasing maturity) and classified as less (LeM), medium and more (MoM) mature. Then fruit were randomized into batches of 30 fruits, each one corresponding to a storage atmosphere (apples: CA, NA; pears: CA, NA, DCA) or to a storage temperature (peaches, nectarines: 0, 4°C). After storage, fruit were put in shelf life at 20°C to reach the ripening degree for consumption. Sensory analyses (QDA profiles) were carried out on LeM and MoM fruit using a panel of 10 assessors. Our results indicate that, for all the species, besides the influence of storage conditions, there was also a great influence of TRS maturity classification at harvest. MoM apples and pears developed physiological disorders such as mealiness and graininess when stored in NA, whereas showed well balanced sensory characteristics when stored in CA and DCA, becoming after storage soft, juicy, sweet, but sour enough. MoM nectarines stored both at 0 and 4°C became woolly, while the LeM ones stored at 0°C developed the best sensory characteristics. MoM peaches stored at 0°C showed the best sensory profile and the LeM ones stored at 4°C the worst. So TRS maturity classification at harvest can give indications on the best storage conditions in order to obtain fruit with sensory characteristics than can satisfy the consumer
Reconstruction of absorber concentrations in a two-layer structure by use of multidistance time-resolved reflectance spectroscopy
No full textTime-resolved spectroscopy and imaging in diffusive media applied to medical diagnostics
No full textPubblicazione su invit
Non-destructive assessment of pulp colour in mangoes by time-resolved reflectance spectroscopy: Problems and solutions
No full textPulp colour in mangoes turns from greenish to deep orange with maturity, and is one of the most reliable maturity indices used in several production regions, even if it is a destructive measurement. Time-resolved reflectance spectroscopy (TRS) is a nondestructive technique which simultaneously quantifies the internal optical properties of fruit related to pigments (absorption coefficient, μa) and to structure (reduced scattering coefficient, μs') by probing the pulp at a depth of 1-2 cm with no or limited influence from the skin. TRS has been used to study the internal fruit attributes related to maturity; the μa measured at harvest at 630-670 nm has been used to predict softening rate during shelf life in nectarines and mangoes. The results obtained in 2011-2012 seasons with Brazilian mangoes are presented analysing various aspects and problems of the TRS measurement for this type of fruit. The relationships between maturity at harvest measured by μa, TRS optical properties in shelf life, fruit softening and pulp colour were studied in 'Haden', 'Palmer' and 'Tommy Atkins' mangoes. 'Haden' and 'Palmer' fruit (less advanced maturity) could be sorted using μa650-μa690, near the chlorophyll absorption peak. In contrast, 'Tommy Atkins' fruit, which were selected for shipping (more advanced maturity), were successfully sorted according to μa540, near the carotenoids absorption peak. It was confirmed that TRS non-destructively measures pulp colour, as shown by the high correlations between μa540 and a∗, hue and yellowness index (IY) and the good performances of PLS models based on μa540-900 spectra for a∗, hue and IY prediction
Time-resolved reflectance spectroscopy as a management tool for late-maturing nectarine supply chain
Full text linkThe 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
In-situ analysis of fruit anthocyanins by means of total internal reflectance, continuous wave and time-resolved spectroscopy
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