The effects of ambient temperature storage on the chemical and nutritional characteristics of phosphoric and sorbic acid-stabilized fish autolysates were determined. Variations in sample composition due to autolysis, deboning, and acidification were also evaluated. Autolysates of English sole (Parophrys vetulus), true cod (Gadus macrocephalus), Dover sole (Microstomus pacificus), and orange rockfish (Sebastodes pinniger) carcass wastes, whole Pacific hake (Merluccius productus) and dogfish shark (Squalis acanthias), and a hake/tuna viscera (70/30 wt/wt) mixture were utilized in the investigation. Samples were acidified to ca. pH 3.25 with phosphoric acid (85% w/v) and contained potassium sorbate at the 0.2% (wt/wt) level. Screen separation of bone reduced the ash levels of samples, with the exception of dogfish shark. Loss of bone minerals, specifically calcium and phosphorus, was responsible. Phosphoric acid addition elevated ash and phosphorus contents to higher levels than for raw materials. Acid-stabilized autolysates were stable to microbial outgrowth throughout 8 months of ambient temperature storage. Slight increases in pH levels were generally observed. Sorbate levels decreased at an apparently exponential rate with respect to time (r=-.9146, P [greater than or equal to] .005). Hydrolytic rancidity did not proceed during storage. Stability towards microbial outgrowth, inactivation of endogenous lipases during pasteurization, and maintenance of acidic environmental conditions enhanced fat stability. Oxidative rancidity, as measured by 2-thiobarbituric acid (TBA) numbers, progressed during storage. Carcass wastes showed higher rates and overall levels of oxidation. Initial free fatty acid levels correlated in a linear manner with 0 and 4 month TBA numbers (r=.9548, P [greater than or equal to] .005; r=.9187, P [greater than or equal to] .005, respectively). The regression of TBA numbers at 4 months on zero time values increased in a linear manner (r=.9346, P [greater than or equal to] .005). Proteolysis during storage, as monitored by free amino groups, was not detected. Inactivation of native proteases during processing and the microbial stability of samples were responsible. Levels of available e-amino lysine and tryptophan were stable throughout storage. The protein quality of acidified hake, dogfish shark, orange rockfish, and English sole autolysates, stored for 0, 4, and 8 months, was evaluated using protein efficiency ratio (PER) determinations. Protein quality was not affected by storage in samples of acidified hake, English sole, and orange rockfish (P=.05). Ratios for all samples of hake and the 0 and 8 month samples of dogfish shark did not vary significantly (P=.05) from the casein control. English sole and orange rockfish samples yielded PER values that were inferior to casein and round fish samples (P=.05). The regression of feed consumption and PER values on TBA numbers decreased in a linear manner (r=-.7999, P [greater than or equal to] .005; r=-.8424, P [greater than or equal to] .005, respectively). Higher contents of nutritionally inferior visceral proteins and increased rates of oxidative rancidity in the carcass waste samples probably were responsible for their reduced protein qualities. / Graduation date: 1978

The Federal Water Pollution Control Act Amendments of 1972 prohibits the discharge of seafood processing solid wastes into navigable waters after July 1, 1977. Oregon shrimp and crab processors must use other methods of disposal for the 15 to 30 million pounds of solid waste generated annually. The application of shrimp and crab wastes to nearby agricultural land can consume the wastes generated at major processing ports. As they came from the processing plant, shrimp and crab solid wastes contained 1.3% to 1.6% N, 0.47% to 0.54% P, other nutrients, 7% to 14% CaCO��� equivalent, and 64% to 78% water. A greenhouse experiment was established to determine the effects of 1) grinding the wastes, 2) surface vs. incorporated waste applications, and 3) waste applications vs. inorganic N applied at equivalent N rates (56, 168, and 336 kg N/ha) with applications of P, S, and lime supplied with the inorganic N only. The fertilizer materials were applied on two coastal soils, and two pasture crops were grown. Forage yields and the P concentration in 'Potomac' orchard grass (Dactylis glomerata L.) were significantly higher with incorporated waste applications than with surface waste applications. Application method did not affect the P concentration in New Zealand white clover (Trifolium repens L. ). The difference in crop response between application methods would assumably be less under field conditions than was measured in the greenhouse. Grinding crab waste significantly increased forage yields when the waste was surface applied, but not when incorporated with the soil. Unground shrimp waste gave significantly higher forage yields than ground shrimp waste. No significant difference occurred in the forage yields, the N uptake by orchardgrass, or the P concentrations in orchardgrass and white clover among applications of shrimp waste, crab waste, and inorganic nutrients with lime. Applications of shrimp and crab wastes increased white clover yields over the control by a factor of more than 3.5 on Knappa silt loam (pH 4.9 - 5.0) but did not measurably increase the soil pH. It was assumed that the wastes, in the immediate area of the shell material, increased the availability of Ca, P, S, and Mo, decreased soluble soil Al, and allowed effective rhizobial nodulation and N fixation. Increasing application rates of shrimp and crab wastes to Knappa and Nehalem silt loams significantly increased the extractable soil P and Ca, and significantly decreased the extractable soil K after 28 weeks of orchardgrass growth. No consistent effect on soil pH was measured. In a second greenhouse experiment, N rates of 165 and 330 kg/ha and P rates of 61 and 122 kg/ha were supplied by shrimp waste and by inorganic sources to a limed coastal soil in a 2 x 2 x 2 complete factorial arrangement. Applications of shrimp waste resulted in significantly higher orchardgrass yields and P uptake than applications of the inorganic nutrients, but no significant difference occurred in the N uptake. In an irrigated coastal pasture, fresh shrimp waste was applied at 6,726, 17,936, and 35,872 kg/ha and ammonium phosphate (16-20-0 15 S) was applied at 224 and 448 kg/ha and a stand of orchardgrass was established. Forage yields were higher with shrimp waste than with ammonium phosphate. Shrimp waste applications beyond 17,936 kg/ha did not further increase the forage yield or P uptake. Shrimp waste applications increased extractable soil P, SO��� -S, soluble salts, and NO��� -N, but resulted in a depletion of soil K when measured at the end of the growing season. Shrimp and crab processing wastes are effective sources of N and P for crop plants and should be applied at rates necessary to supply the recommended rates of N. / Graduation date: 1978

Gelatin was extracted from shark and salmon skins by an enzyme aided process. A three factor, two level central composite rotatable design was used to optimize the process. The factors were namely, enzyme: dry fish skin weight ratio, incubation time, and temperature. The data were analyzed by response surface methodology to determine the optimum conditions for the deproteinization, demineralization and extraction process variables. / Optimum conditions for deproteinization of shark skin by trypsin was about 25°C for 3h, and an E/S ratio of 0.08% (w/w). That for salmon was optimum at 25°C for 1 h with an E/S ratio of 1:1000. The ash content of the shark skins was reduced to over 80% at optimum demineralization conditions of 0.7M citric acid at 25°C for 3h. / Demineralised salmon skins treated with pepsin at an E/S ratio of 0.02% (w/w) for 1h at 25°C resulted in maximum gelatin yield ranging from 7--8%. For shark, the maximum yield was between 18--20% at an E/S ratio of 0.02% (w/w) for 3h at 25°C. The chemical and enzyme treatments had an effect on the viscosity, bloom value and molecular weight for both salmon and shark gelatins.

No description available.

Pacific whiting and its by-products were good raw materials for high quality fish sauce production. Heat stable and salt activated enzymes were responsible for autolytic activity in Pacific whiting and by-products. According to temperature profiles of raw materials at various salt concentrations, two fermentation temperatures, 35°C and 50°C, were selected and compared at 25% salt under static atmospheric condition. Higher yields and faster production rate were obtained from samples incubated at 50°C. Therefore, the apparent optimum condition for fish sauce fermentation using Pacific whiting and its by-products was at 50°C with 25% salt under static atmospheric condition. All physicochemical characteristics, except color and browning color, reached the level of commercial fish sauce within 20 days. Nitrogen contents in all samples reached the level of commercial fish sauce (16.3 g-N/mL) within 112 days. Predominant microorganisms found during fermentation were Staphylococcus, Bacillus and Micrococcus. Alpha-amino acid content appeared to be identified as a good parameter to estimate total nitrogen content during fermentation (adjusted R²=0.84). Soluble solid was a good index for protein degradation in fermentation (adjusted R²=0.71). Proteolytic activity in Pacific whiting and its by-products were investigated using hemoglobin as substrate. Specific substrates and specific inhibitors were also used to classify the types of enzymes responsible for protein degradation in fish sauce fermentation. Serine proteases, cathepsin L-like enzymes and metalloproteases were active at 50°C in whole fish. However, trypsin-like enzymes, and cathepsin L-like enzymes were responsible for protein degradation in by-products at 50°C. At 35°, whole fish was degraded by serine proteases, cathepsin B-like enzymes, trypsin-like enzymes, and metalloproteases. Cysteine proteases were mainly responsible for the degradation of proteins in by-products, and serine proteases and trypsin-like enzymes had a minor role in hydrolyzing of by-products during fermentation. / Graduation date: 2000

Both liquid and solid wastes from Pacific whiting surimi manufacturing were characterized and value-added products were recovered. A proteinase in surimi wash water (SWW) was determined to be cathepsin L with Mr 54,200 on SDS-substrate gel. Heat treatment and acidification shifted the activity zone to M [subscript r] 39,500. No evidence of calpain, cathepsin B or H activity was found. Cathepsin L from SWW was recovered by ohmic heating (55°C for 3 min), ultrafiltration, and freeze-drying with overall yield of 0.83 g protein/L SWW and 78% recovery of activity. A 5.9 purification fold was achieved by these processes. The recovered enzyme had an optimum activity at pH 4.0 and showed preferable hydrolytic activity towards casein, acid-denatured hemoglobin and myofibrils. β-Mercaptoethanol, dithiothreitol and urea enhanced the enzyme activity. The recovered proteinase showed 18.5% residual activity after 7 wk storage at 4°C. Proteolytic activity in solid waste and digestive organs from Pacific whiting was investigated. Pepsin-like proteinase predominated in solid waste, while trypsin-like proteinase was predominant in viscera. Carboxypeptidase b was found in both viscera and solid waste. Protein hydrolysate was produced from Pacific whiting solid waste (PWSW) using commercial proteinase, Alcalase, under optimum hydrolysis conditions. Enzyme concentration, reaction time and waste/buffer ratio affected the hydrolysis and nitrogen recovery (NR). Correlation between the degree of hydrolysis (DH) and NR was high (R₂=0.978). Freeze-dried hydrolysate contained 79.97% protein and showed similar amino acid composition to PWSW and Pacific whiting muscle but tryptophan was reduced. With different DH (20, 30, 40, 50, 60%), surface hydrophobicity, total and surface sulfhydryl content decreased as the DH increased. The hydrolysate showed a high solubility over a wide pH range. Fat adsorption and fat binding capacity were reduced, while foam expansion was enhanced with an increased DH. Hydrolysate with DH of 30% showed highest emulsifying activity. Low emulsion stability and high foam stability were obtained in all hydrolysates tested. Hydrolysate showed antioxidant activity, but no obvious differences in activity were found with varying DH and hydrolysate concentrations. / Graduation date: 1997

Biochemical properties, functional properties, and market potential of Pacific whiting (PW) fish sauce were investigated. Biochemical properties of fish sauce made from whole fish (W) and a mixture (1:1) of whole fish and surimi byproducts (WB) were compared. Market potential was evaluated through phone interviews and consumer panelists. Proteolysis was primarily affected by cathepsin B-like and L-like enzymes. Acidic pH (4-5) with low salt concentration (15-20%) provided a greater degree of hydrolysis (DH), total nitrogen, and amino nitrogen content in PW fish sauce compared to the traditional process. The greatest Angiotensin Converting Enzyme (ACE) inhibition (96.8%) was found in samples fermented with 15% salt at pH 5.0 for 30 days. Anti-oxidative activity (AT) increased when fermentation continued and depended on fermentation pH. Peptides with MW <590 Da possibly played an important role in ACE inhibition. Consumer tests disclosed no significant difference in flavor liking and overall liking among fish sauce samples (W, WB, and commercial anchovy fish sauce). / Graduation date: 2004

Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Please refer to full text for abstract / AFRIKAANSE OPSOMMING: Sien asb volteks vir opsomming

Fish and crab processing wastes were ground and ensiled with corn stover or peanut hulls alone and with 5% dry molasses or 1% formic acid in 3.8 liter cardboard containers double lined with polyethylene. The wastes and roughages were ensiled in proportion to give dry matter levels of 40, 50 and 60%. The seafood wastes were also ensiled with wilted Johnsongrass with and without molasses. After ensiling, average pH for mixtures with fish waste was 6.5, compared to 8.0 for mixtures with crab waste. Addition of dry molasses resulted in a decrease (P <.01) of pH to 5.6 for the ensiled fish mixture but had no effect on the crab waste mixtures. Lactic acid was higher (P< .01) for ensiled mixtures containing fish waste than for those containing crab waste. Substantial levels of acetic acid were present in the silages. Butyric acid levels were higher in silages containing crab waste and decreased linearly (P< .01) with increased dry matter levels. Desirable ensiling was observed for the mixture of fish waste and Johnsongrass. Coliforms and fecal coliforms were decreased or elIminated by ensiling. In a large silo study, mixtures of finfish and crab processing wastes were mixed with wheat straw and ensiled in 210 liter metal drums, double lined with polyethylene bags. Proportions of the fish and straw were 70:30 and 51:49, wet basis, while that of the crab was 60:40 and 40:60. Acetic acid was added to the crab waste mixtures to lower the initial pH to 4.5. After ensiling all mixtures containing fish and straw showed a decrease in pH. Addition of acetic acid to mixtures containing crab waste inhibited fermentation, but resulted in a very stable product. In a sheep digestion trial, dry matter digestibility was higher (P <.01) for the 70:30 diet than for the 51:49 fish diet. There was no difference in dry matter digestibility between the crab silages. Crude protein digestibility was higher (P <.01) for diets containing ensiled fish, compared to diets containing ensiled crab. Nitrogen retention was positive for sheep receiving all diets. Nitrogen retention was higher (P <.01) for animals fed the crab silage diets, compared to those receiving diets containing fish silage. There was a trend for P absorption to be higher in animals fed crab silage. In the sheep palatability trial, intake of dry matter was higher (P < .01) for sheep consuming the crab silage diet and lowest (P <.01) for sheep fed the 70:30 fish silage diet. / Ph. D.

Thesis (MSc Food Sc )--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The focus of this study was the development of food products produced from the neck flesh of Cape hake (Merluccius capensis) as a means of adding value to hake heads. The product prototypes that have been developed include curried fish chowder (packaged in stand-up pouches), fish spread (packaged in plastic casings) and Chakalaka hake (packaged in both cans and retortabie pouches). A formula for fish stock, which was used as a base ingredient in the three product prototypes, has also been standardised. Shelf life testing was regarded an essential part of the development processes for the refrigerated product prototypes i.e. the curried fish chowder and the fish spread. Shelf life determinations involved microbiological testing based on set microbiological standards as well as sensory monitoring and pH testing. Proximate chemical- and mineral analyses were performed on freeze-dried samples of the developed product prototypes. The efficiency of the antimicrobial peptides enterocin 1071 A and 1071 B, as biological preservatives, versus that of conventional artificial preservatives was evaluated in the fish spread prototype. Three batches of fish spread were prepared: one containing the enterocin crude extract; the second a combination of sodium benzoate and potassium sorbate, while the third batch containing no preservatives served as the control. Microbiological- and histamine tests coupled with organoleptic monitoring and pH testing were carried out over a 21-day period. It was concluded that although enterocins 1071A and 1071B had some preserving effect in the fish spread, the artificial preservative combination was the superior preserving agent. However, neither the biological preservatives nor the artificial preservative combination succeeded in providing a satisfactory shelf life. The preserving agents used in this study were however not necessarily included at optimum levels and higher levels could possibly lead to an improved shelf life. The influence of two processing temperatures [121°C (249.8°F) and 116°C (240.8°F)] and two food container types (retortable pouch and can) on the sensory quality characteristics of the Chakalaka hake-prototype was investigated. The results indicated that the shorter processing time obtained with a higher processing temperature resulted in a product of better sensory quality. The sensory quality characteristics of Chakalaka hake processed in cans at 121°C were closest to that considered desirable for the product. / AFRIKAANSE OPSOMMING: Die fokus van hierdie studie was die ontwikkeling van voedselprodukte geproduseer uit die nekvleis van stokvis (Merluccius capensis) met die doeI om waarde by stokviskoppe te voeg. Die volgende produk-prototipes is ontwikkel: 'n dik vissop met 'n kerriegeur (verpak in regopstaande sakkies), 'n vissmeer (verpak in plastiekomhulsels) en Chakalaka hake (verpak beide in blikkies en retortbestande sakkies). 'n Formule vir visaftreksel, wat as 'n basis-bestanddeel in die drie produk-prototipes gebruik is, is ook gestandaardiseer. Rakleeftydstudies het 'n belangrike deel van die ontwikkelingsprosesse van die verkoelde produk-prototipes, d.i. die dik vissop en die vissmeer, uitgemaak, Rakleeftydbepalings het mikrobiologiese toetsing, gebaseer op vasgestelde mikrobiologiese standaarde, sowel as die monitor van sensoriese eienskappe en pH metings behels. Proksimale chemiese- en mineraal analises is uitgevoer op gevriesdroogde monsters van die ontwikkelde produk-prototipes. Die effektiwiteit van die antimikrobiese peptiede enterosien 1071 A en 1071 B, as biologiese preserveermiddels, is ondersoek in vergelyking met dit van konvensionele kunsmatige preserveermiddels in die vissmeer-prototipe. Drie mengsels vissmeer is berei waarvan die eerste enterosien kru-ekstrak bevat het; die tweede 'n kombinasie van natrium bensoaat en kalium sorbaat, terwyl 'n derde mengsel geen preserveermiddels bevat het nie en gedien het as kontrole. Mikrobiologiese- en histamien toetse is gelyklopend met organoleptiese monitering en pH metings oor 'n tydperk van 21 dae op monsters van die drie vissmeermengsels uitgevoer. Die ondersoek het getoon dat enterosien 1071 A en 1071 B wel 'n mate van bederfwering in die vissmeer meegebring het, maar dat die kunsmatige preserveermiddelkombinasie 'n beter preserveringseffek gehad het in die produk. Nie die biologiese preserveermiddels óf die kunsmatige preserveermiddelkombinasie kon 'n bevredigende rakleeftyd teweegbring nie. Die preserveermiddels in hierdie studie is egter nie noodwendig in optimale hoeveelhede gebruik nie en hoër vlakke kan moontlik tot 'n verbeterde rakleeftyd lei. Die effek van twee prosesseringstemperature [121 °C (249.8°F) en 116°C (240.8°F)], sowel as twee verpakkingstipes (retortbestande sakkie en blik), op die sensoriese kwaliteitseienskappe van die 'Chakalaka hake' -prototipe is ondersoek. Die resultate het aangedui dat die korter prosesseringstyd verkry met 'n hoër prosesseringstemperatuur, gelei het tot 'n produk van beter sensoriese gehalte. Die sensoriese kwaliteitseienskappe van 'Chakalaka hake' geprosesseer in blikke by 121°C was die naaste aan dit wat beskou word as gewens vir die produk.