Color of rainbow trout (Oncorhynchus mykiss) fillets by image and sensory analysis, and correlation with SalmoFan numbers.

A total of 72 male and 50 female trout (Oncorhynchus mykiss) fillets were weighed (range 328-794 g, mean 546.2 ± 101.8 g; and range 426-994 g, mean 672.2 ± 106.1 g, respectively), the pictures of whom were taken in a light box, and image analysis was done to measure pixel colors, length, and view area of the fillets. Weight (W) was predicted using view area (V) obtained by image analysis using linear (W = A + BV), and power (W = AVB ) equations. R2 values were between 0.823 and 0.937. Although there was no difference between mean L* and a* values of male and female fillets, significant differences were found between mean b* values (p < 0.05). The colors of SalmoFan™ (SF) mini were also measured by image analysis and their mean L*, a*, b* values, and their entire color index (ECI) and reduced RGB values from 122 images were calculated. A total of 96 untrained panelists were asked to select the SF color of 5 representative fillets and to designate which point on the fillet image best described the SF color chosen. To predict SF numbers of the fillets by image analysis, four cases were considered: (1) whole fillet, (2) whole fillet with pixels a* > 25, (3) a rectangle along the length of the fillet to approximate panelists' selection, and (4) pixels in this rectangle with a* > 25. Mean L*a*b* values, mean reduced RGB values, and mean ECI of the four cases were used to predict fillet SF numbers. Different results obtained imply that image analysis can do repeatable and objective SF color classification of fillets, depending on the pixel selection method, and the color representation. PRACTICAL APPLICATION: Rainbow trout fillets can be assigned SalmoFan (SF) numbers using image analysis of the fillets. However, the selection of pixels and the color representation method affect the results. If these are standardized, SF numbers can be assigned objectively and automatically.

Comparison of three image-analysis-based visual texture calculation methods: energy, entropy, and texture change index.

BACKGROUND: Three image analysis methods to measure visual texture were applied to an image with much texture (scaled carp), and one with little texture (mirror carp). For each method, the effect of image rotation at 0°, 10°, 20°, 30°, 45°, 60°, 75° and 90° was evaluated. RESULTS: Rotation did not change energy (E) and entropy (H) calculations using image histograms. Using co-occurrence matrices with different step size d (1-19 in increases of 2) and step angle θ (0°, 45°, 90° and 135°) showed that, as d increased, E decreased and H increased, and the number of legitimate pixel pairs decreased linearly. Averaging E and H at different θ values rendered the results rotation invariant. Theoretically, the 'texture primitives' method is not rotation independent. However, the variation in texture change index (TCI) with image rotation was negligible. Also, the increase in TCI between the less textured image and the more textured image was 5.3-11. In comparison, the E values from histograms for the images above were 0.0069-0.0081. For co-occurrence matrix-based calculations, at d = 1 and for all θ, E range was from 220 to 389 for scaled carp and from 232 to 412 for mirror carp. CONCLUSION: The more than doubling of TCI for these images implies that it is a more precise method than energy and entropy to discern between visual texture levels. © 2022 Society of Chemical Industry.

Effect of different microwave power levels on inactivation of PPO and PME and also on quality changes of peach puree.

The effect of microwave (MW) treatment with different power densities (4.4, 7.7, and 11.0 W/g) on polyphenol oxidase (PPO) and pectin methyl esterase (PME) inactivation in peach puree were studied, and the changes in color, rheological properties, total polyphenol and flavonoid and antioxidant capacity were evaluated. By using time/temperature data collected during MW heating, three cook values levels (0.36, 10, 24 min) for each power density were calculated. The PPO was significantly decreased from ca. 50% to ca. 5% when increasing the cook value level, regardless of power density applied. While PME significantly decreased from 40.6% to 10.2% when power density increased from 4.4 to 11.0 W/g at cook value 24 min. MW treatment did not alter the flow behaviour of peach puree. The apparent viscosity values of peach puree significantly increased after MW treatment with increasing cook value, regardless of power density applied. The L* values of peach puree significantly increased from 36.98 to 38.10 or more after MW treatment at cook value 10 min and 24 min. MW treatment could maintain the amount of total polyphenol, total flavonoid and antioxidant capacity, preserving the nutritional and functional values of the product.

The effect of ultrasound on particle size, color, viscosity and polyphenol oxidase activity of diluted avocado puree.

The effect of ultrasound treatment on particle size, color, viscosity, polyphenol oxidase (PPO) activity and microstructure in diluted avocado puree was investigated. The treatments were carried out at 20 kHz (375 W/cm(2)) for 0-10 min. The surface mean diameter (D[3,2]) was reduced to 13.44 µm from an original value of 52.31 µm by ultrasound after 1 min. A higher L(∗) value, ΔE value and lower a(∗) value was observed in ultrasound treated samples. The avocado puree dilution followed pseudoplastic flow behavior, and the viscosity of diluted avocado puree (at 100 s(-1)) after ultrasound treatment for 1 min was 6.0 and 74.4 times higher than the control samples for dilution levels of 1:2 and 1:9, respectively. PPO activity greatly increased under all treatment conditions. A maximum increase of 25.1%, 36.9% and 187.8% in PPO activity was found in samples with dilution ratios of 1:2, 1:5 and 1:9, respectively. The increase in viscosity and measured PPO activity might be related to the decrease in particle size. The microscopy images further confirmed that ultrasound treatment induced disruption of avocado puree structure.

Quantification of visual characteristics of whipped cream by image analysis and machine vision: method development.

The appearance (color, shine, surface roughness, bumpiness, view area, height) of whipped cream samples change with time. Quantitative methods based on image analysis were developed to measure these parameters in cream samples stored at 3 temperatures (room temperature, 10 °C and 2 °C) for up to 24 h. There was a small decrease in L* and a* values over time, and a significant increase in b* values. ΔE values suggest that these color changes are significant and observable (2.96 for room temperature, 9.46 for 10 °C, 12.6 for 2 °C). Difference between polarized and nonpolarized images was used to quantify shine. The length of a laser line over the cream sample was measured to quantify the change in bumpiness of the surface (33.8%, 41.78%, and 33.27% reduction in laser line length for room temperature, 10 °C, and 2 °C, respectively). For room temperature stored samples, most changes occurred during the first 5 min. For samples stored at 10 °C and 2 °C, most changes occurred during the first 30 min. Turn angles data did not provide useful information. The changes in view area depended on temperature: at room temperature the area increased over time, at 10 °C it increased first then decreased; at 2 °C the view area decreased over time. Correlation of the results of these methods with sensory evaluation can make the evaluation of the appearance of whipped cream more objective, repeatable, and quantitative.

Method to measure the force to pull and to break pin bones of fish.

A texture measurement device was modified to measure the force required to pull pin bones from King salmon (Oncorhynchus tshawytscha), snapper (Pagrus auratus), and kahawai (Arripis trutta). Pulled bones were also subjected to tension to measure the breaking force. For all fish, the pulling force depended on the size of the fish, and on the length of the pin bone (P < 0.05). In general, larger fish required greater pulling force to remove pin bones. For example, fresh small salmon (about 1500 g whole) required 600 g on average to pull pin bones, and large fish (about 3700 g whole) required 850 g. Longer bones required greater pulling force. The breaking force followed the same trend. In general, the breaking force was greater than the pulling force. This allows the removal of the bones without breaking them. There was no statistically significant (P > 0.05) difference between the forces (both pulling and breaking) from fresh and frozen/thawed samples, although in general frozen/thawed samples required less force to pull. With the quantification of pulling and breaking forces for pin bones, it is possible to design and build better, "more intelligent" pin bone removal equipment.

Effects of dry brining, liquid smoking and high-pressure treatment on the physical properties of aquacultured King salmon (Oncorhynchus tshawytscha) during refrigerated storage.

BACKGROUND: Aquacultured King salmon (Oncorhynchus tshawytscha) pieces were dry brined with a salt/brown sugar mix, dipped in liquid smoke for 3 min, vacuum packed, high hydrostatic pressure (HHP) treated at 600 or 200 MPa for 5 min and stored at 4 °C for up to 40 days. RESULTS: The surface redness (average a*) of the samples increased after dry brining, then decreased after liquid smoke treatment. HHP did not change the outside color of liquid-smoked samples. However, the inside color changed depending on pressure. HHP-treated control samples without dry brining and liquid smoking changed to a pale pink color. HHP at 600 MPa resulted in a significant increase in hardness. Compared with fresh samples, dry-brined samples had reduced water activity, while samples dipped in liquid smoke had lower pH values. CONCLUSION: Dry brining and liquid smoking protect the outside color of salmon against changes caused by HHP. The increase in hardness may counteract the softening of the smoked salmon tissue over time.

Color change of the snapper (Pagrus auratus) and Gurnard (Chelidonichthys kumu) skin and eyes during storage: effect of light polarization and contact with ice.

Ten gurnard and 10 snapper were stored on ice. One side always contacted the ice; the other side was always exposed to air. At different intervals for up to 12 d, the fish were placed in a light box, and the images of both sides were taken using polarized and nonpolarized illumination. Image analysis resulted in average L*, a*, and b* values of skin, and average L* values of the eyes. The skin L* value of gurnard changed significantly over time while that of snapper was substantially constant. The a* and b* values of both fish decreased over time. The L* values of eyes were significantly lower for polarized images, and significantly lower for the side of fish exposed to air only. This may be a concern in quality evaluation methods such as QIM. The difference of colors between the polarized and nonpolarized images was calculated to quantify the reflection off the surface of fish. For accurate measurement of surface color and eye color, use of polarized light is recommended.

Quantification of pizza baking properties of different cheeses, and their correlation with cheese functionality.

The aim of this study is to quantify the pizza baking properties and performance of different cheeses, including the browning and blistering, and to investigate the correlation to cheese properties (rheology, free oil, transition temperature, and water activity). The color, and color uniformity, of different cheeses (Mozzarella, Cheddar, Colby, Edam, Emmental, Gruyere, and Provolone) were quantified, using a machine vision system and image analysis techniques. The correlations between cheese appearance and attributes were also evaluated, to find that cheese properties including elasticity, free oil, and transition temperature influence the color uniformity of cheeses.

Image analysis method to quantify the effect of different treatments on the visual meat/shell ratio of half-shelled green lipped mussels (Perna canaliculus).

BACKGROUND: Aquacultured green lipped mussel (Perna canaliculus) is the New Zealand export leader of seafood in terms of weight. Different treatments shrink mussel meat differently and affect the consumer perception of half-shelled mussels. In order to quantify this, digital images of half-shelled green lipped mussels subjected to two postharvest treatments (ultrahigh pressure (UHP) and heat treatment (HT)) and raw controls were taken. The ratio of the view area of the meat to that of the shell (labelled as 'visual condition index' (VCI)) was measured using image analysis. A polygonal region of interest was defined on the image to depict the boundary of the meat and to calculate the view area. RESULTS: Raw mussels had a VCI of 85%. HT mussels had a much reduced VCI of 41%, indicating shrinkage of the meat due to heat. UHP treatment used as a shucking method resulted in a VCI of 83%. Since VCI is one measure of quality for the consumer, this quantitative method can be used in the optimization of shucking treatment (HT or UHP). CONCLUSION: VCI can be used to optimize postharvest treatments to minimize meat shrinkage. This method can also be applied to other shellfish such as oysters and clams.

Phytochemical, sensory attributes and aroma stability of dense phase carbon dioxide processed Hibiscus sabdariffa beverage during storage.

The effect of dense phase carbon dioxide (DPCD) processing (34.5 MPa, 8% CO2, 6.5 min, and 40 °C) on phytochemical, sensory and aroma compounds of hibiscus beverage was compared to a conventional thermal process (HTST) (75 °C for 15 s) and a control (untreated beverage) during refrigerated storage (4 °C). The overall likeability of the hibiscus beverage for all treatments was not affected by storage up to week 5. DPCD process retained more aroma volatiles as compared to HTST. Aroma profiles in the beverages were mainly composed of alcohols and aldehydes with 1-octen-3-ol, decanal, octanal, 1-hexanol, and nonanal as the compounds with the highest relative percentage peak areas. A loss of only 9% anthocyanins was observed for the DPCD processed hibiscus beverage. Phytochemical profiles in the hibiscus beverage included caffeoylquinic acids, anthocyanins, and flavonols. No major changes in total phenolics and antioxidant capacity occurred during the 14 weeks of storage.

Quantification of gaping, bruising, and blood spots in salmon fillets using image analysis.

UNLABELLED: An image analysis method was developed to quantify the gaping, bruising, and blood spots of red salmon (Oncorhynchus nerka) fillets. Images of 15 fillets with various levels of gaping were taken either with a dSLR camera, or with a video camera. Also, the same fillets were recorded using the same camera both under regular illumination, and under polarized illumination. In either case, light at an angle was used to highlight the gapes in the flesh. An image analysis method was developed that can adaptively apply an L*threshold value to the image depending on the average color of the fillet, and quantify the resulting percent of the fillet area that has an L* value less than or equal to L*threshold. Polarized lighting changed the color by eliminating artifacts resulting from reflections. It is recommended to use polarized light for this purpose. Both cameras could be used adequately to quantify defects. The proper setting of the L*threshold value depended on the camera and on the polarized light. No correlation could be found between the average L* value of the fillets and the L*threshold value. It was possible to quantify the gaping, bruising, and blood spots on the salmon fillets using this method, which can be the first step toward the automation of this operation. PRACTICAL APPLICATION: Gaping, bruising, and blood spots can be recognized and quantified by analyzing images of salmon fillets. Polarized light is recommended to eliminate color artifacts caused by reflected light. This can be used to automate the detection of these defects.

Inactivation kinetics of Vibrio vulnificus in phosphate-buffered saline at different freezing and storage temperatures and times.

UNLABELLED: Vibrio vulnificus (Vv) is a pathogen that can be found in raw oysters. Freezing can reduce Vv and increase the shelf life of oysters. The objective of this study was to develop predictive inactivation kinetic models for pure cultures of Vv at different frozen storage temperatures and times. Vv was diluted in phosphate-buffered saline (PBS) to obtain about 10(7) CFU/mL. Samples were frozen at -10, -35, and -80 °C (different freezing rates), and stored at different temperatures. Survival of Vv was followed after freezing and storage at -10 °C (0, 3, 6, and 9 d) and at -35 and -80 °C (every week for 6 wk). For every treatment, time-temperature data was obtained using thermocouples in blank vials. Predictive models were developed using first-order, Weibull and Peleg inactivation kinetics. Different freezing temperatures did not significantly (α = 0.05) affect survival of Vv immediately after freezing. The combined effect of freezing and 1 wk frozen storage resulted in 1.5, 2.6, and 4.9 log10 reductions for samples stored at -80, -35, and -10 °C, respectively. Storage temperature was the critical parameter in survival of Vv. A modified Weibull model successfully predicted Vv survival during frozen storage: log10 Nt = log 10No - 1.22 - ([t/10{-1.163-0.0466T}][0.00025T(2) + 0.049325]). N(o) and N(t) are initial and time t (d) survival counts, T is frozen storage temperature, Celsius degree. PRACTICAL APPLICATION: Vibrio vulnificus can be inactivated by freezing. Models to predict survival of V. vulnificus at different freezing temperatures and times were developed. This is the first step towards the prediction of V. vulnificus related safety of frozen oysters.

Physicochemical and phytochemical properties of cold and hot water extraction from Hibiscus sabdariffa.

UNLABELLED: Hibiscus cold (25 °C) and hot (90 °C) water extracts were prepared in various time-temperature combinations to determine equivalent extraction conditions regarding their physicochemical and phytochemical properties. Equivalent anthocyanins concentration was obtained at 25 °C for 240 min and 90 °C for 16 min. Total phenolics were better extracted with hot water that also resulted in a higher antioxidant capacity in these extracts. Similar polyphenolic profiles were observed between fresh and dried hibiscus extracts. Hibiscus acid and 2 derivatives were found in all extracts. Hydroxybenzoic acids, caffeoylquinic acids, flavonols, and anthocyanins constituted the polyphenolic compounds identified in hibiscus extracts. Two major anthocyanins were found in both cold and hot extracts: delphynidin-3-sambubioside and cyanidin-3-sambubioside. In general, both cold and hot extractions yielded similar phytochemical properties; however, under cold extraction, color degradation was significantly lower and extraction times were 15-fold longer. PRACTICAL APPLICATION: Hibiscus beverages are prepared from fresh or dried calyces by a hot extraction and pasteurized, which can change organoleptic, nutritional, and color attributes. Nonthermal technologies such as dense phase carbon dioxide may maintain their fresh-like color, flavor, and nutrients. This research compares the physicochemical and phytochemical changes resulting from a cold and hot extraction of fresh and dried hibiscus calyces and adds to the knowledge of work done on color, quality attributes, and antioxidant capacity of unique tropical products. In addition, the research shows how these changes could lead to alternative nonthermal processes for hibiscus.

Classification of impacted blueberries during storage using an electronic nose.

BACKGROUND: An electronic nose (EN) was used to determine the effect of repeated impacts on changes in volatile characteristics of fresh blueberries during storage. Hand-harvested 'Misty' blueberries (Vaccinium corymbosum) were treated either as (1) undropped (control) fruits, (2) fruits poured six times from a picking bucket 200 mm into a plastic field lug or (3) fruits dropped as above ten times onto a steel surface. Fruits from all treatments were stored in vented polystyrene clamshell containers at 2 °C and 95% relative humidity. RESULTS: Repeated impacts caused no skin rupture or leakage after treatment or during storage. EN data were subjected to discriminant function analysis to classify samples by treatment at days 0, 2, 10, 17 and 24 (n=5 per treatment). Correct classification rates (CCRs) for days 0, 2, 10, 17 and 24 were 0, 100, 100, 100 and 100% respectively. On day 0 there was no significant difference in sample volatiles, and CCRs for all treatments and storage times ranged from 80 to 100%. Cross-validation rates for different treatments and storage times ranged from 75 to 100%. CONCLUSION: The EN could be a useful tool to estimate the effect of impacts incurred during blueberry handling on quality based on changes in volatile characteristics.

Using image analysis to predict the weight of Alaskan salmon of different species.

After harvesting, salmon is sorted by species, size, and quality. This is generally manually done by operators. Automation would bring repeatability, objectivity, and record-keeping capabilities to these tasks. Machine vision (MV) and image analysis have been used in sorting many agricultural products. Four salmon species were tested: pink (Oncorhynchus gorbuscha), red (Oncorhynchus nerka), silver (Oncorhynchus kisutch), and chum (Oncorhynchus keta). A total of 60 whole fish from each species were first weighed, then placed in a light box to take their picture. Weight compared with view area as well as length and width correlations were developed. In addition the effect of "hump" development (see text) of pink salmon on this correlation was investigated. It was possible to predict the weight of a salmon by view area, regardless of species, and regardless of the development of a hump for pinks. Within pink salmon there was a small but insignificant difference between predictive equations for the weight of "regular" fish and "humpy" fish. Machine vision can accurately predict the weight of whole salmon for sorting.

Prediction of the weight of Alaskan pollock using image analysis.

Determining the size and quality attributes of fish by machine vision is gaining acceptance and increasing use in the seafood industry. Objectivity, speed, and record keeping are advantages in using this method. The objective of this work was to develop the mathematical correlations to predict the weight of whole Alaskan Pollock (Theragra chalcogramma) based on its view area from a camera. One hundred and sixty whole Pollock were obtained fresh, within 2 d after catch from a Kodiak, Alaska, processing plant. The fish were first weighed, then placed in a light box equipped with a Nikon D200 digital camera. A reference square of known surface area was placed by the fish. The obtained image was analyzed to calculate the view area of each fish. The following equations were used to fit the view area (X) compared with weight (Y) data: linear, power, and 2nd-order polynomial. The power fit (Y = A · X(B)) gave the highest R(2) for the fit (0.99). The effect of fins and tail on the accuracy of the weight prediction using view area were evaluated. Removing fins and tails did not improve prediction accuracy. Machine vision can accurately predict the weight of whole Pollock. Practical Application: The weight of Alaskan Pollock can be predicted automatically by taking the image of the fish and using it in one of the correlations developed in this study. The removal of the fins or the fins and the tail did not increase the prediction accuracy of the method. Therefore, intact fish images should be used.

Microbial inactivation and shelf life of apple juice treated with high pressure carbon dioxide.

Apple juice prepared from 'Annurca' apple puree was treated with a HPCD batch system. The pH, degrees Brix, color parameters and microbial load of the treated apple juice were compared with those of thermally processed juice. Thermal processes were carried out at 35, 50, 65, 85 degrees C and treatment times ranging between 10 and 140 minutes. Microbial inactivation kinetics indicated that 5-log reduction of natural flora in apple juice was achieved at 85 degrees C and 60 minutes of treatment time for conventional thermal process and at 16.0 MPa, 60 degrees C and 40 minutes for HPCD process. Results suggested that temperature played a fundamental role on HPCD treatment efficiency, with inactivation significantly enhanced when it increased from 35 to 60 degrees C. Less significant was the role of the pressure at the tested levels of 7.0, 13.0 and 16.0 MPa. Also, 5-log reduction of natural flora in apple juice was obtained at lower temperatures by cyclic treatments of six compression and decompression steps. There were no significant differences between treated and untreated samples in degrees Brix (alpha = 0.05). Significant differences were detected in pH values between the untreated and HPCD treated samples (alpha = 0.05). There was a significant decrease in 'L*' and 'b*' values and also differences were detected in 'a*' values between the untreated and the HPCD treated samples (alpha = 0.05). Statistical analysis for degrees Brix, pH and color data showed no differences between the untreated and HPCD treated samples in the first 2 weeks of storage at 4 degrees C. These results emphasize the potential use of HPCD in industrial applications.

Enhancing the retention of phytochemicals and organoleptic attributes in muscadine grape juice through a combined approach between dense phase CO2 processing and copigmentation.

This study evaluated the phytochemical stability and organoleptic attributes of an ascorbic acid-fortified muscadine grape juice as affected by dense phase CO2 processing (DP-CO2) and addition of thyme polyphenolic cofactors (Thymus vulgaris; 1:100 anthocyanin-to-cofactor molar ratio) in efforts to prevent phytochemical losses that occur during storage of anthocyanin-containing beverages, especially in the presence of carbonyl compounds commonly produced during thermal processing and storage. DP-CO2 processing insignificantly altered initial juice phytochemical and antioxidant content, whereas thermal pasteurization reduced anthocyanins (263 mg/L), ascorbic acid (42 mg/L), soluble phenolics (266 mg/L), and antioxidant capacity (6 microM Trolox equivalents/mL). Similar trends were observed during storage, and data showed that increasing the CO2 level from 8 to 16% during DP-CO2 was instrumental in reducing juice phytochemical and antioxidant degradation. Copigmentation was instrumental in retaining higher anthocyanin, soluble phenolics, and antioxidant capacity during storage without affecting initial juice aroma and flavor characteristics. Moreover, on the basis of overall likeability scores, panelists preferred copigmented juices, which had increased juice color intensity and masked the detrimental color fading that occurred during storage, especially when compared to thermally pasteurized juices. DP-CO2 and copigmentation were effective strategies to reduce phytochemical and color deterioration that occurred in muscadine juice during storage without affecting their organoleptic attributes.

Microbial stability, phytochemical retention, and organoleptic attributes of dense phase CO2 processed muscadine grape juice.

Dense phase CO2 processing (DP-CO2) is a promising alternative to thermal pasteurization potentially inactivating microorganisms without affecting food phytochemicals or organoleptic characteristics. To demonstrate these effects, studies were conducted by changing processing pressure and CO2 concentration in relation to microbial destruction. Subsequent storage stability (10 weeks at 4 degrees C) of muscadine grape juice processed by DP-CO2 (34.5 MPa at 8% or 16% CO2) was evaluated and compared to a heat-pasteurized juice (75 degrees C, 15 s). Thermal pasteurization decreased anthocyanins (16%), soluble phenolics (26%), and antioxidant capacity (10%) whereas no changes were observed for both DP-CO2 juices. DP-CO2 juices also retained higher anthocyanins (335 mg/L), polyphenolics (473 mg/L), and antioxidant capacity (10.9 micromol of Trolox equivalents/mL) than thermally pasteurized juices at the end of storage. Insignificant differences in sensory attributes (color, flavor, aroma, and overall likeability) were observed between unprocessed and DP-CO2 juices, while significant differences were observed between unprocessed and heat-pasteurized juices. Panelists preferred DP-CO2 over heat-pasteurized juices throughout the first 6 weeks of storage, whereby the growth of yeast and mold adversely affected the juice aroma. Comparable microbial counts were observed between DP-CO2 and thermally pasteurized juices during the first 5 weeks of storage. DP-CO2 protected phytochemicals in muscadine juice during processing and storage without compromising microbial stability or sensory attributes over 5 weeks of storage.