Progress 06/01/15 to 01/31/16
Outputs
Target Audience:The primary target audiences are the harvesters, processors, and consumers of blue and snow crabmeat. Harvesters and processors will realize greater value and marketability of their crab resources as a result of the proposed work and commercialization of restructured (gelled) raw crabmeat. Consumers will realize greater versatility and value in products and dishes prepared from restructured raw crabmeat, and enhanced flavor and succulence in these products as well. A secondary target audience is the scientific community and processors of other raw muscle products. The work will demonstrate means of consistently producing acceptable gels from pastes of raw muscles via a protein pre-aggregation step. Changes/Problems:Additional studies were conducted with respect to the use of both heat-induced, and high pressure processing (HPP) induced, gelation of raw crab meat. These processes were found to be useful in producing new products from raw crab meat which will fill unique market niches. What opportunities for training and professional development has the project provided?Phase I allowed for Dr. Tyre Lanier to include both a NCSU Masters candidate and visting post-doctoraite research scientist to participate in novelapplication of thier specialties to raw blue crab meat. How have the results been disseminated to communities of interest?The work related to this SBIR funded research is being treated as primarilyconfidential. We were able to present a poster at IFT15. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The blue crab industry along the US east coast has dramatically declined in favor of imports from low cost labor markets abroad due to labor required for hand-picking of cooked crabs. Shure Foods found that mechanical extraction of raw meat from uncooked blue crabs allows up to a 300% increase in meat yield versus that obtained by traditional hand-picking of cooked crabs. Using a patented cold-structured gelation process, Shure Foods has been able to produce a raw crab meat product with physical qualities similar to other raw seafood. This could herald a return of domestic crabbing along the Atlantic coast of the US. Snow crabs from the northern Pacific and Atlantic are typically sold cooked in the shell and hence the shell appearance is of vital importance. Snow crabs with broken or blemished shells (30% of the typical harvest) are thus deemed unsuitable for this market. Therefore, fishermen typically selectively harvest younger or newly molted crabs, depleting the reproducing population of crabs. Mechanical extraction of the blemished snow crabs will allow for greater harvest efficiency (less waste) plus better fishery management. The Phase I research addressed the challenge of consistently and reliably converting raw crabmeat paste, which can naturally vary widely in its properties due to both natural and processinduced factors, into a cold-structured gel product by the application of commercial food-grade cross-linking transglutaminase (TG) enzyme (Dough, 2012). Work leading up to Phase I had shown variability in cold gelling ability among several lots of fresh or frozen raw crabmeat. The frozen samples that did gel well exhibited higher paste viscosity, lighter color and a more granular appearance, suggesting denaturation/aggregation of proteins during frozen storage. It was hypothesized that the inconsistency in gelling ability was likely due to variability in the degree to which raw crabmeat proteins had aggregated prior to application of the cold-structuring TG. The goal of the Phase I research was to identify one or more protein aggregating treatments that could be used commercially to reliably and consistently induce cold structured gelation, per the Shure Foods patent. Frozen storage (over time) and/or the addition of a low concentration of a food-grade calcium salt (immediately) induced sufficient protein denaturation leading to commercially acceptable cold structuring. This cold gelling technology was also applied to raw paste from snow crabs, a fishery where the mechanical extraction of raw meat offers expanded opportunities for solving problems and opening new markets. For this species, melanosis, or enzymatic discoloration, of the meat was found to be a greater issue than was the reliability of the TG-induced cold gelling reaction; this new concern will be addressed in the Phase II proposal. Supplemental investigations opened two new possibilities for markets of raw crab meat from any species. It was shown that raw crab meat paste can potentially be utilized by present producers of fish (surimi)-based 'imitation crab' products to offer a 'real crab' restructured alternative, to replace both these imitation analog products (better label) as well as more expensive, handpicked cooked crab meat (lower cost). Additionally, high pressure processing (HPP) was found to induce sufficient binding of roller extracted, more fibrous, raw crabmeat so that a cold formed and pasteurized, raw 'crab lump' product may be marketed. The overall objective of the Phase I SBIR study was to identify protein aggregating treatments that would be commercially acceptable and ensure reliable gelation of raw (uncooked) crab meat paste by the Shure Foods patented cold structuring method [i.e. by the addition of TG-based binding agents]. The resultant cold-structured raw crab-meat product can be more easily manipulated for food formulation and preparation, thereby enhancing its marketability and utility as a food item (Dough 2012). Sample preparation: The bulk of the work was carried out with fresh, raw blue crab meat harvested off the coast of North Carolina. Harvested live crabs were treated one of three ways: (a) backed/gutted, then mechanically (soft belt) de-shelled and the resulting paste frozen at -50oC(control samples); these samples were tested soon after initial processing; (b) backed/gutted and immediately frozen (frozen in-shell samples) then stored at -20oC (conventional commercial storage temperature) for various times prior to thawing, mechanical de-shelling, and testing; (c) backed/gutted, then mechanically de-shelled and the resulting paste stored frozen at -20oC (frozen de-shelled samples). All backing/gutting and mechanical deshelling was conducted by Shure Foods and the resulting de-shelled meat was transferred to the Food, Bioprocessing and Nutrition Sciences (FBNS) department at NC State University for storage at -50oC (control samples) or -20oC (frozen in-shell, or de-shelled samples). Snow crabs harvested in Norway were quick frozen in-shell and shipped to Shure Foods for deshelling and paste preparation within one week. Cold structuring/Gelation of crab meat paste (based on Shure Food Patent): The procedure involves mixing crab paste with meat-binders (TG-system) before packing the paste into closed, cylindrical containers and storing at 5°C for 18-24 h to effect cold gelation. Gelation was best achieved using 2% dry Fibrimex® (mammalian TG+fibrinogen; Fx Technology and Products USA LLC, Fremont NE). Somewhat more variable results were obtained in most cases when using Activa® dry microbial TG + casein or fish gelatin substrate mixtures (Ajinomoto North America Inc., Ft. Lee NJ) and this data is not included. Methods/treatments to induce protein denaturation and/or aggregation: Preliminary work suggested that extended frozen storage might promotes protein aggregation sufficient to induce acceptable gelation. Three treatments were evaluated for their impact on pre-aggregation of proteins: frozen storage (time/temperature and whether storage occurred with shelled ordeshelled crab), mild heating, and addition of aggregating additives. Assessment of treated crab paste and gelation: Protein solubility, pH, calcium content (only control and frozen in-shell samples) and/or paste whiteness was assessed on crab pastes. Protein solubility was measured in 0.6M KCl solution (induces solubility of all meat proteins) and protein concentration in the supernatant measured by the ortho-phthaldialdehyde method (Park et al. 1987, 1988). Calcium content was determined by the Dry Ash-Acid Dissolution-AAS method (Perkin-Elmer 1996). Whiteness of crab meat was measured by reflectance colorimetry (Puebla 2006) while pH of a 1:10 dilution of the meat was measured using a standard pH meter. The gel strength (stress at gel fracture) was evaluated on a gelled sample using a ball probe punch test while gel deformability (deformation at fracture) was measured using a standardized double fold test on a 3mm slice of gelled sample (Park et al. 2014). Criteria for acceptable gel texture: Based on input from Shure Foods experience in marketing the cold gelled raw crabmeat product, for culinary applications an acceptable gel was found to exhibit a minimum single fold without breaking, with a stress at fracture of minimum about 15 gF, also with no perceptible stickiness of the gel surface (an evidence of incomplete gelation).
Publications
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