Progress 10/01/99 to 09/30/04
Outputs
In the production of fish fillet, more than 50 percent is waste, and bone represents about 15 percent of the fish weight. On the dry matter basis, the pure bone contains about 30 percent protein, mainly collagen. This work focuses on the gelatin extraction from Alaska Pollock bone. Frozen pollock bone was defrosted overnight at 2.5C. The adhering meat was hydrolyzed by using 1 percent Corolase at 60C for 20 min. Bones were washed with distilled water and broken down to 5-7 mm particles. Gelatin was extracted using either distilled water or different buffers (pH 2.6 C 10.1). Total protein of the supernatant (3,500 rmp for 10 min) was measured with the Lowry method. The bone residue was extracted two more times. Hyroxyproline content was measured with the Woessner method. Fish skin gelatin was used as the control for measuring the gel strength and 5 percent of the total skin protein was replaced with bone protein. Gel strength was determined using 10ml of 3 percent (at
10C) or 2.3 percent (at 2.5C) protein. The Multiple Duncan Range Test was used for comparing the means (for at least two replications). Although Corolase may solublise some gelatin, the subsequent extract gives higher gel strength due to higher purity of the extract. The loss of bone weight after enzyme treatment and the total solids of the cleaned bone were 62.0 and 40.2 percent, respectively. On a dry matter basis, enzyme cleaned bone and bone residues have 12.9 and 10.0 percent protein that contain 10.43 and 13-14.2 percent hydroxyproline, respectively. The solublized gelatin hydroxyproline percentage varies between 5-8 percent, mainly 6-7.5 percent. Extraction of gelatin in three steps increases the yield of protein recovery up to 45 percent. Raising the extraction temperature up to 70C will increase the yield of protein recovery significantly, but not the hydroxyproline content, or the gel strength at 2.5C. By increasing extraction time up to 90 min, the yield of gelatin
increases but the gel strength at both 2.5 and 10C does not vary significantly. By using sodium citrate buffer, the protein extraction shows a higher yield at pH around 3-4, but was not significant. However, except for pH around 3.3 and 4.7, all the samples using citrate buffer with pH less than 5.8 had significantly lower protein yield. By increasing the pH to alkaline range, the yield significantly increases. The average protein recovery at pH 9.5 is significantly higher than pH 3.3. The gel strength of all samples was less than the control (Bloom 83). At pH 4.7-5.8, it was significantly lower than control and the other samples at 2.5C. All the gels in the acidic range were more fragile than the gels in the alkaline range when tested for gel strength. The fragility decreased by increasing of the pH. The pH of gels varied from 5.6-7.6 while the pH of control was 6.5.
Impacts
The use of fish gelatin would create new opportunities for the fishing industry to use by-products, would give the food industry an ingredient with greater functional flexibility and permit the industry to more easily maintain kosher/halal status, and give the consumer new opportunities for foods and provide more religiously acceptable foods.
Publications
- No publications reported this period
|
Progress 01/01/01 to 12/31/01
Outputs
Initial work focused on optimizing the use of a commercial fish gelatin in water dessert gels. This work sought to duplicate the earlier work showing that fish gelatin is actually preferred in some cases because of more flavor intensity probably due to faster flavor release because of the lower melting point. Current work is focusing on using fish gelatin in yogurt to determine the impact of melting point on the perception of a more complex food product. Initial efforts on this project have focused on optimizing the yogurt product using a home "yogurt-maker" that can simultaneously make six samples. Sugar and vanilla levels have been optimized and the amount of gelatin is currently being optimized.
Impacts
The use of fish gelatin would create new opportunities for the fishing industry to use by-products, would give the food industry an ingredient with greater functional flexibility and permit the industry to more easily maintain kosher/halal status, and give the consumer new opportunities for foods and provide more religiously acceptable foods.
Publications
- No publications reported this period
|
Progress 01/01/00 to 12/31/00
Outputs
We have established a number of benefits of fish gelatin. For example, the fact that one can get the same Bloom as with beef and pork gelatins, but have the flexibility to optimize product quality by selecting the optimum melting temperature. And second, that fish gelatin is actually preferred by panelists because of less off flavor and odor, and greater (quicker) flavor release. Our research emphasis at this point is on three areas. The first is to now attempt to obtain fish gelatin from fish bones. For this purpose we need to remove any adhering flesh from the bones, preferably in a way that permits the hydrolysate to be recovered as a value added product. For this purpose the benefit of formic acid fish silage is being investigated. The second emphasis is on product optimization. The third is to get greater gelling power from the weak to non-gelling skin gelatins such as salmon, possibly by use of the transglutaminase system.
Impacts
Gelatin is probably the most important food ingredient not readily available as kosher and halal, particularly for the normative mainstream US kosher standard. As kosher foods comprise around 40% of manufactured foods, the absence of cost-effective kosher gelatin is a major limitation in the expansion of this market. At the same time, with fish resources dwindling, there is a real need to increase the total value and total utilization of fish by-products. Fish gelatin is potentially one of the most lucrative of such options.
Publications
- Choi, S.-S. and J.M. Regenstein. 2000. Physicochemical and Sensory Characteristics of Fish Gelain. J. Fd. Sci. 65:194-199.
|
Progress 01/01/99 to 12/31/99
Outputs
Fish gelatin provides an economically beneficial way to use fish parts, particularly skin and bones. The fish gelatin can be prepared with a range of Blooms (gel strength) similar to that for beef and pork gelatin, while permitting a range of melting points from almost equal to beef/pork (30C) to much lower (8C). Food products need to be optimized for their best melt temperature, e.g., what gelatin melting temperature do consumers prefer for a "Swiss-style" yogurt? Preliminary sensory work shows that the fish gelatin is actually preferred by the panelist compared to commercial pork gelatin. A faster and stronger flavor release is particularly apparent. Gelatin from bone can be successfully obtain, although most current commercial fish gelatin is made from fish skins. Salmon gelatins continue to be a challenge, as they do not gel or gel very weakly. The use of transglutaminase (a crosslinking enzyme) as a possible solution to the problem will be explored. The impact of
this crosslinking on various other gelatins and their functional properties also needs to be explored. The fish gelatins are particularly desirable for products that can be used in the kosher and halal food markets, as most beef and pork gelatins are unacceptable to the mainstream segments of these markets.
Impacts
Commercial fish gelatin is slowly appearing in the marketplace in various forms. Better utilization, lower production costs, and improved product are anticipated results of this work.
Publications
- No publications reported this period
|
|