Gloss Evaluation of Curved-surface Fruits and Vegetables

CsCER6 and CsCER7 Influence Fruit Glossiness by Regulating Fruit Cuticular Wax Accumulation in Cucumber

Fruit glossiness is an important external fruit quality trait that greatly affects the marketability of fresh cucumber (Cucumis sativus) fruits. A few reports have suggested that the extent of cuticular wax loading influences the glossiness of the fruit surface. In the present study, we tested the wax contents of two inbred cucumber lines, comparing a line with waxy fruit (3401) and a line with glossy fruit (3413). Wax content analysis and dewaxing analysis demonstrate that fruit cuticular wax loads negatively correlate with fruit glossiness in cucumber. Identifying genes that were differentially expressed in fruit pericarps between 3401 and 3413 and genes induced by abscisic acid suggested that the wax biosynthesis gene CsCER6 (Cucumis sativus ECERIFERUM 6) and the regulatory gene CsCER7 may affect wax accumulation on cucumber fruit. Expression analysis via RT-qPCR, GUS-staining, and in situ hybridization revealed that CsCER6 and CsCER7 are abundantly expressed in the epidermis cells in cucumber fruits. Furthermore, the overexpression and RNAi lines of CsCER6 and CsCER7 showed dramatic effects on fruit cuticular wax contents, fruit glossiness, and cuticle permeability. Our results suggest that CsCER6 and CsCER7 positively regulate fruit cuticular wax accumulation and negatively influence fruit glossiness.

Development of a Freshness Index for Fruit Quality Assessment—Using Bell Pepper as a Case Study

(1) Background: This special issue contains new developments in the field of fresh produce quality. Freshness provides the appeal for the consumer to purchase a particular horticultural produce. Freshness is a combination of size, colour, shape, flesh firmness, turgescence and glossiness without wilting, which imply that the produce has been picked only a short while ago and has not suffered any decay during harvest, transport or storage. (2) Objective: The objective of the present work was to develop potential freshness indices. The indices are based on non-invasive, real-time measurements, using changes in surface appearance after harvest, using Bell pepper as the most difficult model. (3) Methods: The selection criteria were a dramatic change in values over 14 days of storage at 17 °C, and either a consistent decrease or increase without peaks and troughs. Only two (out of five) non-invasive techniques were selected, i.e., surface glossiness, measured non-destructively using a luster sensor (type CZ-H72 from Keyence Co., Osaka, Japan) and light reflection spectra, recorded by a spectrometer, whereas the three techniques fruit firmness (penetrometer), colorimeter (e.g., Minolta) and false colour images (profilometer) were excluded. (4) Results: The first technique based on fruit glossiness provides luster values depending on fruit colour. Green Bell pepper fruit with a Fresh Index in excess of 463–490 a.i. can be classified as fresh, and similarly of 525–565 a.i. for yellow and 486–502 a.i. for red pepper fruit. This first Freshness index dropped, indicating a lesser freshness, to less than 100 a.i. after 14 days storage, irrespective of fruit colour, thereby providing a suitable wide, ca. 5-fold, range of parameterization. The second index is based on the difference between the light reflectance peaks at 630–633 nm and at 500 nm, also measured perpendicular to the convex fruit side. These percentage values decreased from >40% with fresh red and yellow Bell pepper to ca. 20% after 14 days storage; similarly, these percentages decreased from ca. 16% to ca. 8% in green pepper fruit, in both cases by a twofold factor. Overall, a third Freshness index could be a combination of luster values larger than 470 a.u. and >40% difference of the light reflectance between 630 nm and 500 nm. (5) Conclusions: Two viz three freshness indices are proposed and thresholds elaborated for Bell pepper fruit. The analysis showed that both indices viz technologies, luster and light reflection spectra, require colour differentiation, i.e., a specific index for yellow, red and green Bell pepper fruit.

Postharvest quality assessment of apple during storage at ambient temperature

In this study, the physical and chemical quality attributes of apples were measured experimentally during the storage after harvesting, using well-defined procedures and techniques. Overall quality index (OQi) models were formulated in terms of measured quality attributes. Firmness (F) and total soluble solids (TSS) varied from 11.88 ± 0.25 to 7.68 ± 0.24 N and 14.1 ± 0.1 to 12.7 ± 0.1 % Brix, respectively, whereas acidity and density varied from 0.163 ± 0.003 to 0.081 ± 0.001 % and 0.995 ± 0.003 to 0.951 ± 0.004 gm/cm³, respectively. The gloss values at 45° and 60° angles of incidence were found to be in the range of 7.9 ± 0.2 to 4.1 ± 0.3 and 6.8 ± 0.1 to 2.5 ± 0.3, respectively whereas, the Hunter color values L, a, b were found to be in the range of 51.75 ± 1.33 to 57.01 ± 0.98, 24.20 ± 0.86 to 30.12 ± 1.13, and 19.53 ± 1.61 to 22.96 ± 1.12, respectively. Formulated models were validated with the sensory scores. OQi predicted by the Model ML2 was found to be in consonance with the variation in the sensory overall quality scores. The OQi, as per the model ML2, was estimated as the ratio of the product of the constant C (265.5), acidity (A), and firmness (F) to the mod of the product of Hunter color values a and b. Finally, the predicted values of OQi were correlated with the measured quality parameters to check the possibility of predicting OQi non-destructively by using any one of those measured attributes during the storage.

Changes in pectin characteristics of jujube fruits cv "Dongzao" and "Jinsixiaozao" during cold storage

Softening is one of the main factors affecting market value and consumer preferences for jujubes, and it was closely related to the modification and depolymerization of pectin. Changes in characteristics of three pectins (water-soluble pectin (WSP), sodium carbonate-soluble pectin (SSP) and chelate-soluble pectin (CSP)), including their contents, degree of methylesterification (DM), neutral sugar compositions, the molecular weight (M_w ) distributions and nanostructures, from two jujube fruits cv Dongzao (DZ) and Jinsixiaozao (JS) during cold storage were assessed. The results showed that variation in pectin characteristics during cold storage was similar between DZ and JS. The reduction of firmness corresponded to a conversion of water-insoluble pectin to WSP during cold storage. DM of WSP presented an increase trend in the late storage. Rhamnose (Rha), arabinose (Ara) and glucose (Glc) were the crucial compositions in three pectins, and most neutral sugar compositions in three pectins first increased and then decreased during cold storage. Changes in the ratio of (galactose (Gal)+Ara)/Rha and Ara/Gal represented that the branch chains of rhamnogalacturonan-I in three pectins depolymerized after storage. The high M_w in WSP and SSP of jujubes were solubilized and extensively depolymerized into pectin with lower M_w after storage. AFM images showed an increase in short chains and branch structures of three pectins after storage. Overall, three pectins in DZ and JS depolymerized and solubilized during cold storage. WSP and SSP were more contributed to the softening of jujubes compared to CSP, and they played the critical role for regulating the softening of jujube fruits during cold storage. PRACTICAL APPLICATION: Softening is one of the main factors affecting market value and consumer preferences for jujubes, and it was closely related to the modification and depolymerization of pectin. Changes in characteristics of three pectins (WSP, SSP, CSP), including their contents, degree of methylesterification, neutral sugar compositions, the molecular weight distributions and nanostructures, from two jujube fruits cv Dongzao (DZ) and Jinsixiaozao (JS) during cold storage were assessed. Three pectins in DZ and JS depolymerized and solubilized during cold storage. WSP and SSP were more contributed to the softening of jujubes compared to CSP, and they played the critical role for regulating the softening of jujube fruits during cold storage. This study would elucidate the mechanism of jujube softening and help to regulate the postharvest quality during cold storage.

Non-Destructive, Opto-Electronic Determination of the Freshness and Shrivel of Bell Pepper Fruits

(1) The objective of the present study was to identify suitable parameters to determine the (degree of) freshness of Bell pepper fruit of three colors (yellow, red, and green) over a two-week period including the occurrence of shrivel using non-destructive real-time measurements (2) Materials and methods: Surface glossiness was measured non-destructively with a luster sensor type CZ-H72 (Keyence Co., Osaka, Japan), a colorimeter, a spectrometer and a profilometer type VR-5200 (Keyence) to obtain RGB images. (3) Results: During storage and shelf life, bell pepper fruit of initially 230–245 g lost 2.9–4.8 g FW per day at 17 °C and 55% rh. Shriveling started at 6–8% weight loss after 4–5 days and became more pronounced. Glossiness decreased from 450–500 a.u. with fresh fruit without shrivel, 280–310 a.u. with moderately shriveled fruit to 80–90 a.u. with severely shriveled fruit irrespective of color against a background of <40 a.u. within the same color, e.g., light red and dark red. Non-invasive color measurements showed no decline in Lab values (chlorophyll content), irrespective of fruit color and degree of shrivel. RGB images, converted into false color images, showed a concomitant increase in surface roughness (Sa) from Sa = ca. 2 µm for fresh and glossy, Sa = ca. 7 µm for moderately shriveled to Sa = ca. 24 µm for severely shriveled rough surfaces of stored pepper fruit, equivalent to a 12-fold increase in surface roughness. The light reflectance peak at 630–633 nm was universal, irrespective of fruit color and freshness. Hence, a freshness index based on (a) luster values ≥ 450 a.u., (b) Sa ≤ 2 µm and (c) the difference in relative reflectance in % between 630 nm and 500 nm is suggested. The latter values declined from ca. 40% for fresh red Bell pepper, ca. 32% after 6 days when shriveling had started, to ca. 21% after 12 days, but varied with fruit color. (4) Conclusion: overall, it can be concluded that color measurements were unsuitable to determine the freshness of Bell pepper fruit, whereas profilometer, luster sensor, and light reflectance spectra were suitable candidates as a novel opto-electronic approach for defining and parametrizing fruit freshness.

Applications of hyperspectral imaging in chicken meat safety and quality detection and evaluation: a review

Currently, the issue of food safety and quality is a great public concern. In order to satisfy the demands of consumers and obtain superior food qualities, non-destructive and fast methods are required for quality evaluation. As one of these methods, hyperspectral imaging (HSI) technique has emerged as a smart and promising analytical tool for quality evaluation purposes and has attracted much interest in non-destructive analysis of different food products. With the main advantage of combining both spectroscopy technique and imaging technique, HSI technique shows a convinced attitude to detect and evaluate chicken meat quality objectively. Moreover, developing a quality evaluation system based on HSI technology would bring economic benefits to the chicken meat industry. Therefore, in recent years, many studies have been conducted on using HSI technology for the safety and quality detection and evaluation of chicken meat. The aim of this review is thus to give a detailed overview about HSI and focus on the recently developed methods exerted in HSI technology developed for microbiological spoilage detection and quality classification of chicken meat. Moreover, the usefulness of HSI technique for detecting fecal contamination and bone fragments of chicken carcasses are presented. Finally, some viewpoints on its future research and applicability in the modern poultry industry are proposed.

Human cortical areas involved in perception of surface glossiness

Glossiness is the visual appearance of an object's surface as defined by its surface reflectance properties. Despite its ecological importance, little is known about the neural substrates underlying its perception. In this study, we performed the first human neuroimaging experiments that directly investigated where the processing of glossiness resides in the visual cortex. First, we investigated the cortical regions that were more activated by observing high glossiness compared with low glossiness, where the effects of simple luminance and luminance contrast were dissociated by controlling the illumination conditions (Experiment 1). As cortical regions that may be related to the processing of glossiness, V2, V3, hV4, VO-1, VO-2, collateral sulcus (CoS), LO-1, and V3A/B were identified, which also showed significant correlation with the perceived level of glossiness. This result is consistent with the recent monkey studies that identified selective neural response to glossiness in the ventral visual pathway, except for V3A/B in the dorsal visual pathway, whose involvement in the processing of glossiness could be specific to the human visual system. Second, we investigated the cortical regions that were modulated by selective attention to glossiness (Experiment 2). The visual areas that showed higher activation to attention to glossiness than that to either form or orientation were identified as right hV4, right VO-2, and right V3A/B, which were commonly identified in Experiment 1. The results indicate that these commonly identified visual areas in the human visual cortex may play important roles in glossiness perception.

Definition and measurement of statistical gloss parameters from curved objects

Gloss standards are commonly defined for gloss measurement from flat surfaces, and, accordingly, glossmeters are typically developed for flat objects. However, gloss inspection of convex, concave, and small products is also important. In this paper, we define statistical gloss parameters for curved objects and measure gloss data on convex and concave surfaces using two different diffractive-optical-element-based glossmeters. Examples of measurements with the two diffractive-optical-element-based glossmeters are given for convex and concave aluminum pipe samples with and without paint. The defined gloss parameters for curved objects are useful in the characterization of the surface quality of metal pipes and other objects.