Compositional and Functional Characteristics of Materials Recovered from Headed Gutted Silver Carp (Hypophthalmichthys molitrix) By Isoelectric Solubilization and Precipitation Using Organic Acids

Silver carp (Hypophthalmichthys molitrix) is one of the main freshwater fish species with a high nutritional value; however, it is hard to process the fish due to its boney carcass. Therefore, isoelectric solubilization and precipitation (ISP) processing was applied to headed gutted silver carp to separate the protein from the bones, scales, skin, fins, etc. Different solubilization strategies (pH 2.5, 3.0. 11.5 and 12.0) using organic acids, either acetic acid (AA) or a 30% formic and lactic acid combination (F&L), were applied during ISP and the different effects of treatments on the materials recovered from the initial silver carp were compared. The recovered carp proteins were then used to make protein gels similar to surimi with the use of standard food additives. To further assess the effect of using different solubilization pH values and organic acids on the protein quality of the recovered fractions, the functional, texture and color properties were analyzed.;Proximate composition of the recovered proteins showed that processing at basic pH using AA was most effective at removing impurities (i.e. bones, scales, skin, fins) (p\u3c0.05) and the impurities were effectively removed from recovered lipids regardless of processing pH or acid type. Functional properties of gels made from protein recovered by ISP processing using organic acids as the processing acid had typical gelation characteristics. Moreover, it was seen that isoelectrically recovered carp proteins were not denatured and retained functionality. Thermal denaturation and dynamic rheology of the protein gels revealed that using AA under acidic conditions and F&L with alkali treatments yielded improved gel structure. In addition to that, color analysis presented data showing that gels made using F&L were whiter for all solubilization conditions (p\u3c0.05) and were similar to the whiteness of Alaska Pollock surimi gels under acidic treatments. Texture analyses highlighted that gels made from protein solubilized at basic pH values had firmer texture (p\u3c0.05) and were harder and more cohesive, gummy and chewy (p\u3c0.05) than proteins solubilized under acidic conditions. Moreover, gels made from proteins recovered using AA as the processing acid under basic conditions had similar shear stress responses as Alaska Pollock surimi.;This research shows that organic acids have the potential to recover protein and lipid from otherwise hard to process fish by ISP processing. The gels made from recovered carp protein show similar or improved functional, texture and color properties compared to Alaska Pollock surimi depending on the treatment and might be used for the development of restructured fish products for human consumption

Calcium Enhanced Protein Recovery from Underutilized Aquatic Resources and Optimizing Protein Gelation Strategies Using Functional Ingredients

Utilization of aquatic resources has rapidly gained importance. Traditional fish processing does not utilize the majority of the fish, thus generating large quantities of waste that impacts the economy, sustainability and environmental stress adversely. Protein can be extracted from underutilized sources such as silver carp and catfish using a pH shift processing method and incorporated into the human diet. Therefore, myofibrillar proteins were extracted from ground fish using different alkali solubilization and precipitation strategies. The efficacy of protein separation from lipids, and insoluble such as skin, fins, scales and bones were investigated and compared. Protein and lipid recovery yields were calculated to determine the economic feasibility of the procedure by calculating the amount of material recovered out of the available protein or lipids present in the initial material. Mineral content of the recovered protein was analyzed and compared to the initial fish and Alaska Pollock surimi.;Although every factor such as solubilization pH, base, and acid as well as their interactions had a significant effect on the results, effect of processing base was more evident for protein separation. Protein solubility was significantly increased (p\u3c0.05) when calcium hydroxide (Ca(OH)2) was used compared to sodium hydroxide (NaOH). Therefore, protein concentration was also greater (p\u3c0.05) with lower amount of impurities such as lipids and ash when Ca(OH)2 was used as the processing base compared to NaOH at every solubilization pH (11.0, 11.5, 12.0, 12.3) tested in this study.;The recovered protein was then made into protein gels in order to investigate gelation conditions. Fish muscle protein mainly consisting of myosin and actin cross-link and form a gel network upon heating. Yet, the efficiency of gel setting period that allows for the crosslinking to take place depends on a variety of factors mainly impacted by time and temperature. Protein gel texture and color is also affected by post cooking storage. Therefore, widely applied pre-cooking gelation time and temperature strategies, and post-cooking period on texture and color of final protein gels was investigated. Four most commonly applied pre-cooking gelation strategies (no-setting time, 30 min at 25°C, 1 h at 40°C, or 24 h at 4°C) were applied to protein pastes (fish protein concentrate and standard functional additives). After cooking, texture and color were either analyzed directly or after 24 h at 4°C on gels adjusted to room temperature.;Gelation properties as well as protein amount in the recovered protein gels can be changed by salvaging water soluble sarcoplasmic proteins from fish processing water or solution and incorporating them into myofibrillar protein gels. Therefore, sarcoplasmic proteins of silver carp were solubilized and added back to recovered myofibrillar protein or Alaska Pollock in solution form to investigate the impact on texture and color of protein gels. Sarcoplasmic protein amounts tested (77 or 144 mg/kg paste) yielded softer, less gummy, chewy, cohesive and resilient (p\u3c0.05) gels compared gels containing transglutaminase, an exogenous enzyme. In order to investigate the effects of greater amounts of sarcoplasmic proteins in the myofibrillar protein gels, solubilized sarcoplasmic proteins were concentrated, made into a powder using a freeze-dryer and added back into recovered protein gels.;A separate study investigating the effects of starch addition at increasing amounts (0, 5, 10, 15, 20 g/kg paste) determined that most of the textural attributes such as hardness, gumminess, chewiness, firmness and resistance to deformation were higher (p\u3c0.05) for gels containing starch; however, these attributes did not increase with the increasing starch concentration. Therefore, the similar textural properties observed in 23 g/kg paste sarcoplasmic protein containing gels without starch or polyphosphates and gels developed using 5 transglutaminase/kg paste, 15 g starch/kg paste and 3 g polyphosphates/kg paste can be attributed to the gel strengthening properties of high amounts of sarcoplasmic proteins in calcium enhanced myofibrillar protein gels.;Overall, this research shows that Ca(OH)2 is effective in protein solubility and separates proteins from other fractions such as lipids and insolubles when used as a processing base during pH shifts. Ca(OH) 2 solubilization yields a recovered protein fraction enhanced with calcium, and lowered sodium. Therefore, protein recovered using Ca(OH)2 will yield a naturally whiter end product with a more beneficial content. Protein gels made from calcium enhanced protein will be harder and naturally whiter. Moreover, sarcoplasmic protein recovered using simple solubilization steps from fish and by-products may be used as a nutritional supplement to enhance protein content of food products or can be incorporated into functional food products such as protein gels containing lower amounts of sodium. (Abstract shortened by UMI.)

Effects of starch concentration on calcium‐enhanced black bullhead catfish protein gels

Calcium‐enhanced protein recovered from black bullhead catfish was used to develop gels containing increasing amounts of potato starch (0–20 g/kg protein paste) and the effects of starch on functional, textural, and color properties were tested. Energy required to unfold protein groups was greater with the addition of 5 g starch/kg protein paste. Gels containing starch were harder, chewier, and less springy (p \u3c .05) than gels without starch. For most measurements, regression analysis showed that increasing the starch concentration beyond 5 g/kg did not contribute to further significant textural changes. Torsional shear stress and strain along with Kramer shear force increased as the concentration of starch increased (R2 = .79, .79, and .53, respectively). The addition of ≥10 g starch/kg protein paste resulted in darker gels and gels got darker as more starch was added (R2 = .71). Results showed no benefit to increasing starch concentration in gels beyond 5 g starch/kg protein paste

Inter-observer Agreement in Laryngeal Pre-neoplastic Lesions

In this series, laryngeal preneoplastic lesions were evaluated by the classifications of the World Health Organization (WHOC), Ljubljana (LC) and squamous intraepithelial neoplasia (SINC) by multiple observers. The inter-observer agreement (IA) by WHOC for laryngeal lesions had been previously evaluated, but to the best of our knowledge, there are no data for LC and SINC. H&E stained slides from 42 laryngeal biopsies were evaluated by fourteen participants according to WHOC and LC, and SINC was additionally applied by 6. The results were analyzed statistically. The diagnoses which were favored by most participants for each case, according to WHOC, were as follows: squamous cell hyperplasia (n = 5; 12%), mild dysplasia (n = 11; 26.2%), moderate dysplasia (n = 12; 28.6%), severe dysplasia (n = 7; 16.7%), carcinoma in situ (n = 5; 12%), and invasive squamous cell carcinoma (n = 2; 4.8%). There was a significant difference between the participants for all three classifications; some participants gave lower or higher scores than the others. The mean correlation coefficients (MCC) of the participants were higher for WHOC compared to LC (0.55 ± 0.15 and 0.48 ± 0.14, respectively). The mean linear-weighted kappa (wKappa) values of participants were not significantly different (0.42 ± 0.10, 0.41 ± 0.12 and 0.37 ± 0.07 for WHOC, LC and SINC, respectively). The kappa values in this series are in agreement with those in previous literature for WHOC, and the similar results obtained for LC and SINC are novel findings. Although the MCC of WHOC was higher, as the wkappa was not significantly different, the findings in this series are not in favor of any of the classifications for better IA for pre-neoplastic laryngeal lesions. © 2010 Humana

Erratum to: Inter-observer Agreement in Laryngeal Pre-neoplastic Lesions

[No abstract available