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.

FlhG employs diverse intrinsic domains and influences FlhF GTPase activity to numerically regulate polar flagellar biogenesis in Campylobacter jejuni.

Flagellation in polar flagellates is one of the rare biosynthetic processes known to be numerically regulated in bacteria. Polar flagellates must spatially and numerically regulate flagellar biogenesis to create flagellation patterns for each species that are ideal for motility. FlhG ATPases numerically regulate polar flagellar biogenesis, yet FlhG orthologs are diverse in motif composition. We discovered that Campylobacter jejuni FlhG is at the center of a multipartite mechanism that likely influences a flagellar biosynthetic step to control flagellar number for amphitrichous flagellation, rather than suppressing activators of flagellar gene transcription as in Vibrio and Pseudomonas species. Unlike other FlhG orthologs, the FlhG ATPase domain was not required to regulate flagellar number in C. jejuni. Instead, two regions of C. jejuni FlhG that are absent or significantly altered in FlhG orthologs are involved in numerical regulation of flagellar biogenesis. Additionally, we found that C. jejuni FlhG influences FlhF GTPase activity, which may mechanistically contribute to flagellar number regulation. Our work suggests that FlhG ATPases divergently evolved in each polarly flagellated species to employ different intrinsic domains and extrinsic effectors to ultimately mediate a common output - precise numerical control of polar flagellar biogenesis required to create species-specific flagellation patterns optimal for motility.

Uptake of extracellular DNA: competence induced pili in natural transformation of Streptococcus pneumoniae.

Transport of DNA across bacterial membranes involves complex DNA uptake systems. In Gram-positive bacteria, the DNA uptake machinery shares fundamental similarities with type IV pili and type II secretion systems. Although dedicated pilus structures, such as type IV pili in Gram-negative bacteria, are necessary for efficient DNA uptake, the role of similar structures in Gram-positive bacteria is just beginning to emerge. Recently two essentially very different pilus structures composed of the same major pilin protein ComGC were proposed to be involved in transformation of the Gram-positive bacterium Streptococcus pneumoniae - one is a long, thin, type IV pilus-like fiber with DNA binding capacity and the other one is a pilus structure that was thicker, much shorter and not able to bind DNA. Here we discuss how competence induced pili, either by pilus retraction or by a transient pilus-related opening in the cell wall, may mediate DNA uptake in S. pneumoniae.

Secretion of a pneumococcal type II secretion system pilus correlates with DNA uptake during transformation.

Streptococcus pneumoniae is a major human pathogen that successfully adapts to the host environment via an efficient uptake system for free DNA liberated from other organisms in the upper respiratory tract, facilitating immune evasion and drug resistance. Although the initial signaling events leading to pneumococcal competence for DNA transformation and the fate of DNA when it has been taken up have been extensively studied, the actual mechanism by which DNA in the environment may traverse the thick capsular and cell wall layers remains unknown. Here we visualize that induction of competence results in the formation of a native morphologically distinct pilus structure on the bacterial surface. This plaited pilus is encoded by the competence (com)G locus, and, after assembly, it is rapidly released into the surrounding medium. Heterologous pneumococcal pilus expression in Escherichia coli was obtained by replacing the pulE-K putative pilin genes of the Klebsiella oxytoca type II secretion system with the complete comG locus. In the pneumococcus, the coordinated secretion of pili from the cells correlates to DNA transformation. A model for DNA transformation is proposed whereby pilus assembly "drills" a channel across the thick cell wall that becomes transiently open by secretion of the pilus, providing the entry port for exogenous DNA to gain access to DNA receptors associated with the cytoplasmic membrane.

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.

FTT0831c/FTL_0325 contributes to Francisella tularensis cell division, maintenance of cell shape, and structural integrity.

The Francisella FTT0831c/FTL_0325 gene encodes amino acid motifs to suggest it is a lipoprotein and that it may interact with the bacterial cell wall as a member of the OmpA-like protein family. Previous studies have suggested that FTT0831c is surface exposed and required for virulence of Francisella tularensis by subverting the host innate immune response (M. Mahawar et al., J. Biol. Chem. 287:25216-25229, 2012). We also found that FTT0831c is required for murine pathogenesis and intramacrophage growth of Schu S4, but we propose a different model to account for the proinflammatory nature of the resultant mutants. First, inactivation of FTL_0325 from live vaccine strain (LVS) or FTT0831c from Schu S4 resulted in temperature-dependent defects in cell viability and morphology. Loss of FTT0831c was also associated with an unusual defect in lipopolysaccharide O-antigen synthesis, but loss of FTL_0325 was not. Full restoration of these properties was observed in complemented strains expressing FTT0831c in trans, but not in strains lacking the OmpA motif, suggesting that cell wall contact is required. Finally, growth of the LVS FTL_0325 mutant in Mueller-Hinton broth at 37°C resulted in the appearance of membrane blebs at the poles and midpoint, prior to the formation of enlarged round cells that showed evidence of compromised cellular membranes. Taken together, these data are more consistent with the known structural role of OmpA-like proteins in linking the OM to the cell wall and, as such, maintenance of structural integrity preventing altered surface exposure or release of Toll-like receptor 2 agonists during rapid growth of Francisella in vitro and in vivo.

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.

Polar flagellar biosynthesis and a regulator of flagellar number influence spatial parameters of cell division in Campylobacter jejuni.

Spatial and numerical regulation of flagellar biosynthesis results in different flagellation patterns specific for each bacterial species. Campylobacter jejuni produces amphitrichous (bipolar) flagella to result in a single flagellum at both poles. These flagella confer swimming motility and a distinctive darting motility necessary for infection of humans to cause diarrheal disease and animals to promote commensalism. In addition to flagellation, symmetrical cell division is spatially regulated so that the divisome forms near the cellular midpoint. We have identified an unprecedented system for spatially regulating cell division in C. jejuni composed by FlhG, a regulator of flagellar number in polar flagellates, and components of amphitrichous flagella. Similar to its role in other polarly-flagellated bacteria, we found that FlhG regulates flagellar biosynthesis to limit poles of C. jejuni to one flagellum. Furthermore, we discovered that FlhG negatively influences the ability of FtsZ to initiate cell division. Through analysis of specific flagellar mutants, we discovered that components of the motor and switch complex of amphitrichous flagella are required with FlhG to specifically inhibit division at poles. Without FlhG or specific motor and switch complex proteins, cell division occurs more often at polar regions to form minicells. Our findings suggest a new understanding for the biological requirement of the amphitrichous flagellation pattern in bacteria that extend beyond motility, virulence, and colonization. We propose that amphitrichous bacteria such as Campylobacter species advantageously exploit placement of flagella at both poles to spatially regulate an FlhG-dependent mechanism to inhibit polar cell division, thereby encouraging symmetrical cell division to generate the greatest number of viable offspring. Furthermore, we found that other polarly-flagellated bacteria produce FlhG proteins that influence cell division, suggesting that FlhG and polar flagella may function together in a broad range of bacteria to spatially regulate division.

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.

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.

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.

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.

FlhF and its GTPase activity are required for distinct processes in flagellar gene regulation and biosynthesis in Campylobacter jejuni.

FlhF proteins are putative GTPases that are often necessary for one or more steps in flagellar organelle development in polarly flagellated bacteria. In Campylobacter jejuni, FlhF is required for sigma(54)-dependent flagellar gene expression and flagellar biosynthesis, but how FlhF influences these processes is unknown. Furthermore, the GTPase activity of any FlhF protein and the requirement of this speculated activity for steps in flagellar biosynthesis remain uncharacterized. We show here that C. jejuni FlhF hydrolyzes GTP, indicating that these proteins are GTPases. C. jejuni mutants producing FlhF proteins with reduced GTPase activity were not severely defective for sigma(54)-dependent flagellar gene expression, unlike a mutant lacking FlhF. Instead, these mutants had a propensity to lack flagella or produce flagella in improper numbers or at nonpolar locations, indicating that GTP hydrolysis by FlhF is required for proper flagellar biosynthesis. Additional studies focused on elucidating a possible role for FlhF in sigma(54)-dependent flagellar gene expression were conducted. These studies revealed that FlhF does not influence production of or signaling between the flagellar export apparatus and the FlgSR two-component regulatory system to activate sigma(54). Instead, our data suggest that FlhF functions in an independent pathway that converges with or works downstream of the flagellar export apparatus-FlgSR pathway to influence sigma(54)-dependent gene expression. This study provides corroborative biochemical and genetic analyses suggesting that different activities of the C. jejuni FlhF GTPase are required for distinct steps in flagellar gene expression and biosynthesis. Our findings are likely applicable to many polarly flagellated bacteria that utilize FlhF in flagellar biosynthesis processes.

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.

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.

Effects of Combined High Hydrostatic Pressure and Dense Phase Carbon Dioxide on the Activity, Structure and Size of Polyphenoloxidase.

UNLABELLED: High hydrostatic pressure (HHP) may activate undesirable enzymes such as polyphenoloxidase (PPO). Carbon dioxide (CO2 ) addition to HHP could increase enzyme inactivation. We investigated the inactivation of combined HHP and dense phase carbon dioxide process on activity, secondary conformation and size of pure PPO from mushroom. Solutions (2.35µM, in phosphate buffer pH 6.8) were treated with HHP alone (HHP), or 3.6% w/w of CO2 was injected into the package (HHP+CO2). Treatment conditions were 600 MPa, 20 °C, for 1, 3, 5, 7, and 9 min. HHP+CO2 treatment significantly decreased residual enzyme activity (REA) to 30% to 12% after 1 to 9 min, respectively, whereas only HHP had no significant effect. Both HHP and HHP+CO2 treatments caused changes in secondary conformations, however HHP+CO2 changes were more extensive. Alpha-helix fractions were reduced by 32% and 41%, while ß sheet, turn and unordered increased by 63% and 213%, 100% and 71%, and 118% and 82% for HHP and HHP+CO2, respectively after 9 min. The protein size in HHP+CO2 samples was 5- to 6-fold larger than that of Control and HHP treatment, and this increase was inversely correlated with REA. The best inactivation kinetics of HHP+CO2 model was the 2-fractional model with 2 simultaneous 1st-order steps, contributing 70% and 30% to original enzyme activity, with k(labile) = 12.15 min(-1) and k(stable) = 0.07 min(-1), respectively. No recovery in activity, secondary conformation and size in all samples were observed after 1-mo storage. Addition of CO2 in HHP treatment can improve enzyme inactivation, and therefore product shelf-life and quality. PRACTICAL APPLICATION: High hydrostatic pressure (HHP) achieves the safety of foods as a nonthermal method, but it may activate undesirable enzymes resulting in short shelf life due to, for example flavor and color changes. Our study determined that addition of CO2 to HHP has significant effects on enzyme inactivation, secondary conformational and molecular size changes of mushroom PPO. No recovery in activity, secondary conformation and size in all samples were observed after 1 mo storage at 4 °C. This combined process increases product shelf life, in addition to safety and nutrient preservation.

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.

Microbial and Sensory Effects of Combined High Hydrostatic Pressure and Dense Phase Carbon Dioxide Process on Feijoa Puree.

UNLABELLED: High hydrostatic pressure (HHP) is used for microbial inactivation in foods. Addition of carbon dioxide (CO2) to HHP can improve microbial and enzyme inactivation. This study investigated microbial effects of combined HHP and CO2 on Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae, and evaluated sensory attributes of treated feijoa fruit puree (pH 3.2). Microorganisms in their growth media and feijoa puree were treated with HHP alone (HHP), or saturated with CO2 at 1 atm (HHPcarb), or 0.4%w/w of CO2 was injected into the package (HHPcarb+CO2). Microbial samples were processed at 200 to 400 MPa, 25 °C, 2 to 6 min. Feijoa samples were processed at 600 MPa, 20 °C, 5 min, then served with and without added sucrose (10%w/w). Treated samples were analyzed for microbial viability and sensory evaluation. Addition of CO2 enhanced microbial inactivation of HHP from 1.7-log to 4.3-log reduction in E. coli at 400 MPa, 4 min, and reduction of >6.5 logs in B. subtilis (vegetative cells) starting at 200 MPa, 2 min. For yeast, HHPcarb+CO2 increased the inactivation of HHP from 4.7-log to 6.2-log reduction at 250 MPa, 4 min. The synergistic effect of CO2 with HHP increased with increasing time and pressure. HHPcarb+CO2 treatment did not alter the appearance and color, while affecting the texture and flavor of unsweetened feijoa samples. There were no differences in sensory attributes and preferences between HHPcarb+CO2 and fresh sweetened products. Addition of CO2 in HHP treatment can reduce process pressure and time, and better preserve product quality. PRACTICAL APPLICATION: A higher microbial inactivation of Escherichia coli, Bacillus subtilis and Saccharomyces cerevisiae by combining dense phase carbon dioxide and high hydrostatic pressure was observed. For sweetened products there were no significant differences in sensory attributes and preferences between samples treated by the combined method and the fresh samples. In conclusion, addition of CO2 in HHP treatment of juices could reduce process severity and improve product quality.

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.

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.