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1.
Kita A Bråthen E Knutsen SH Wicklund T 《Journal of agricultural and food chemistry》2004,52(23):7011-7016
The aim of this work was to examine the effect of blanching or soaking in different acid solutions on the acrylamide content in potato crisps. Furthermore, the effects of a shorter frying time and a lower frying temperature combined with a postdrying were investigated. Soaking or blanching of potato slices in acidic solutions decreased the pH of potato juice and increased the extraction of amino acids and sugars. Potato crisps obtained after such pretreatments were characterized by lower acrylamide content. The most effective extraction of free amino acids and sugars as well as the largest decrease of acrylamide content (90%) in crisps was obtained when potato slices were soaked in acetic acid solution for 60 min at 20 degrees C. Shorter frying time followed by postdrying resulted in low-moisture potato crisps. Furthermore, the postdrying treatment gave a decreases in acrylamide content of approximately 70% when potato slices were fried at 185 degrees C and approximately 80% when potato slices were fried at 160 degrees C. Effective ways of decreasing acrylamide content in crisps production have been found. Crisps with low acrylamide content and good sensory quality can be obtained either by blanching in acetic acid as pretreatment or by a short frying followed by postdrying. 相似文献
2.
Commercial-Scale Production of Florida Red Tilapia Seed in Low- and Brackish-Salinity Tanks 总被引：2，自引：0，他引：2
Douglas H. Ernst Wade O. Watanabe Lisa J. Ellingson Robert I. Wicklund Bori L. Olla 《Journal of the World Aquaculture Society》1991,22(1):36-44
Commercial-scale production of Florida red tilapia ( Oreochromis sp.) seed (eggs, sacfry, and fry) under methods that minimized freshwater usage was studied on Lee Stocking Island, Bahamas. Comparisons of seed production by broodstock held in low-salinity (LS = 5 ppt; mixed rain and ground water) and brackish-salinity (BS = 18 ppt; mixed ground and sea water) tanks (34 m2 ) showed that seed production over an 8 month period was significantly greater in LS (77.7 seed/m2 / day) than in BS tanks (47.4 seed/m2 /day), with average proportion of brooding females and number of seed per clutch being greater in LS (26.9% and 763) than in BS tanks (19.8% and 643). While LS seed production was among the highest reported values for tilapias, BS production was within reported ranges for fresh and low-salinity tilapia hatcheries. Seed production per unit of low-salinity water (i.e., rain and/or groundwater) consumed in both LS (7,262 seed/m3 ) and BS (5,337 seed/ m3 ) tanks exceeded reported values. The results support the feasibility of commercial-scale production of Florida red tilapia seed under intensive methods and of salinities as high as 18 ppt in regions where fresh or low-salinity water resources are limited. 相似文献
3.
Jane L. Brass Michael B. Rust Bori L. Olla Robert I. Wicklund 《Journal of the World Aquaculture Society》1990,21(3):192-200
The primary objective of this study was to investigate the socio-economic feasibility of saltwater cage culture of Florida red tilapia as a new production activity in Haiti. Market outlets and potential prices for saltwater-reared red tilapia in Haiti were examined. Availability and prices of inputs to production were considered. Although this information was collected in the context of Haiti, it is relevant to other developing countries when assessing the potential for a mariculture industry.
Two types of market outlets for saltwater-reared red tilapia were found to exist in Haiti. The predominant rural market sector treated red tilapia as a low-value species and paid an average price ($0.90/kg roundweight) similar to that for freshwater black tilapia. Urban specialty markets treated red tilapia as a premium quality fish and paid an average price ($2.20/kg cleaned) equal to that for snapper and grouper.
Comparison of production costs to potential market prices indicates that saltwater cage culture of tilapia is not economically feasible on an artisanal scale and is a high financial risk on a commercial scale. Break-even prices are higher than prices in the large rural market sector. No data exists to indicate sufficient demand in the smaller urban specialty market sector or export markets. 相似文献
Two types of market outlets for saltwater-reared red tilapia were found to exist in Haiti. The predominant rural market sector treated red tilapia as a low-value species and paid an average price ($0.90/kg roundweight) similar to that for freshwater black tilapia. Urban specialty markets treated red tilapia as a premium quality fish and paid an average price ($2.20/kg cleaned) equal to that for snapper and grouper.
Comparison of production costs to potential market prices indicates that saltwater cage culture of tilapia is not economically feasible on an artisanal scale and is a high financial risk on a commercial scale. Break-even prices are higher than prices in the large rural market sector. No data exists to indicate sufficient demand in the smaller urban specialty market sector or export markets. 相似文献
4.
Bråthen E Kita A Knutsen SH Wicklund T 《Journal of agricultural and food chemistry》2005,53(8):3259-3264
The effects of adding amino acids on the content of acrylamide in potato crisps, French fries, flat breads, and bread crusts were investigated. Addition of glycine or glutamine during blanching of crisps reduced the amount of acrylamide by approximately 30% compared to no addition. No effect was found in French fries. Addition of glycine during doughmaking significantly reduced acrylamide in both flat breads and bread crusts. In bread crusts the reduction of acrylamide ranged from 50 to >90% depending on the baking condition. In flat breads the reduction varied between 60 and >95%. 相似文献
5.
Wade O. Watanabe Kelly M. Burnett Bori L. Olla Robert I. Wicklund 《Journal of the World Aquaculture Society》1989,20(4):223-229
The reproductive performance of yearling Florida red tilapia broodstock was studied in laboratory aquaria at salinities of 1 (freshwater), 9, 18, 27 and 36 ppt under controlled photoperiod (14 L:10 D) and temperature (28 C).
Spawning was observed at all salinities, although egg production per unit female weight at each spawn was significantly higher at 1 ppt than at higher salinities. An inhibitory effect of salinity on reproductive performance was evidenced by a trend toward lower fertilization, hatching, and survival of prejuveniles with increasing salinity. Fry production per unit female weight declined at salinities above 18 ppt. The results suggest that Florida red tilapia broodstock may be maintained under salinities as high as 18 ppt without impairing fry production, suggesting that hatchery production in brackishwater would be practical in areas where freshwater resources are limiting. 相似文献
Spawning was observed at all salinities, although egg production per unit female weight at each spawn was significantly higher at 1 ppt than at higher salinities. An inhibitory effect of salinity on reproductive performance was evidenced by a trend toward lower fertilization, hatching, and survival of prejuveniles with increasing salinity. Fry production per unit female weight declined at salinities above 18 ppt. The results suggest that Florida red tilapia broodstock may be maintained under salinities as high as 18 ppt without impairing fry production, suggesting that hatchery production in brackishwater would be practical in areas where freshwater resources are limiting. 相似文献
6.
Douglas H. Ernst Lisa J. Ellingson Bori L. Olla Robert I. Wicklund Wade O. Watanabe Jill J. Grover 《Aquaculture (Amsterdam, Netherlands)》1989,80(3-4):247-260
Florida red tilapia (Oreochromis sp.) were reared in 23 m3 seawater (37 ppt) pools. Monosex males (1.3 g mean weight) were stocked at a density of 25 fish/m3 and reared to fingerling size (>10 g) in pools receiving either chicken manure applied at a rate of 105 kg/ha day−1 or pelletized feed (30% protein) administered ad libitum. Following the nursery period, fingerlings in fed pools were reared through adult, marketable sizes.
After 20 days of nursery rearing, mean fish weights (5.7–9.6 g) and survival (77.5–98.6%) in manured pools ranged from less than to greater than values in fed pools (7.9–9.4 g and 95.5–98.2%). By day 33, while mean weights (11.3±0.4 g) and survival (84.5±5.2%) in manured pools were significantly less than those in fed pools (18.0±0.6 g and 95.9±1.4%), fingerling-size fish were obtained from manured pools at an overall productivity of 55 kg/ha day−1.
After 170 days in fed pools, mean fish weight was 467±9 g, survival was 89.7±0.9%, and food conversion was 1.6±0.2. Daily weight gain achieved a maximum of 4.4 g day before a rapid decline in water temperature from 28–29°C to 24–25°C caused a loss of fish appetite and evidence of disease.
The results suggest that while nursery rearing of Florida red tilapia in seawater pools fertilized with chicken manure is feasible, considerable variability in fish performance among pools can be expected, despite identical management methods. In pools receiving prepared feed, high growth rates and survival through adult, marketable sizes suggests a potential for commercial production of Florida red tilapia in seawater. 相似文献
7.
Robert B. McGeachin Robert I. Wicklund Bori L. Olla James R. Winton 《Journal of the World Aquaculture Society》1987,18(1):31-34
Fingerling Tilapia aurea were reared for 90 days in three 1.0 m3 floating cages in seawater (36 ppt) at Lee Stocking Island, Bahamas. Fish stocking density (100, 200 and 400 fish/m3 ) apparently did not affect growth rate but it appears salinity inhibited growth. Daily weight gain and specific growth rate (G) averaged 0.34 g/day and l.08%/day, respectively, for Tilapia aurea fingerlings. Infection of the Tilapia aurea by Bacillus sp. was associated with a significant number of mortalities. The relatively low growth rate and the high incidence of disease and mortality of Tilapita aures in seawater indicate that it may not be a good candidate for cage culture in full-strength seawater. 相似文献
8.
Wade O. Watanabe Kathleen E. French Douglas H. Ernst Bori L. Olla Robert I. Wicklund 《Journal of the World Aquaculture Society》1989,20(3):134-142
Growth of juvenile Florida red tilapin (1.57 g average weight) spawned and sex-reversed (monosex male) at salinities of 4 ppt and 18 ppt was compared at rearing salinities of 18 ppt and 36 ppt in 200 L aquaria under controlled photoperiod (12 L:12 D) and temperature (28 C). Growth was significantly higher for progeny spawned at 18 ppt than those spawned at 4 ppt under both rearing salinities with no difference observed between 18 ppt and 36 ppt.
In another experiment, growth of juvenile progeny (0.98 g average weight) spawned and sex-reversed at salinities of 2 ppt and 18 ppt was compared in 24 m3 outdoor pools at 36 ppt. When water temperatures exceeded 27 C, growth and survival were not significantly different between these groups. However, when temperatures fell below 25 C, growth and survival were significantly higher among progeny spawned at 18 ppt.
The results showed that progeny spawned and reared through early ontqenetic development in brackishwater are better adapted for growth in brackish and seawater and suggested that these fish may have higher resistance to cold-stress in seawater than progeny spawned in freshwater. 相似文献
In another experiment, growth of juvenile progeny (0.98 g average weight) spawned and sex-reversed at salinities of 2 ppt and 18 ppt was compared in 24 m
The results showed that progeny spawned and reared through early ontqenetic development in brackishwater are better adapted for growth in brackish and seawater and suggested that these fish may have higher resistance to cold-stress in seawater than progeny spawned in freshwater. 相似文献
9.
Effect of Feeding Rate on Growth and Feed Conversion of Florida Red Tilapia Reared in Floating Marine Cages 总被引：1，自引：0，他引：1
John H. Clark Wade O. Watanabe Douglas H. Ernst Robert I. Wicklund Bori L. Olla 《Journal of the World Aquaculture Society》1990,21(1):16-24
An experiment was conducted to investigate growth, survival and feed conversion of Florida red tilapia reared in floating cages in seawater under different feeding regimens. Twenty-four cages (1 m3 ) were anchored in a sea pass on Great Exuma, Bahamas, and each was stocked with 300 juvenile, monosex males (10 g mean weight). Growth was monitored every 14 days for 84 days. Fish were fed daily a floating pelletized diet (32% protein) at 4 programed rates representing 50, 70, 90, and 110% of the estimated satiation rate, ad libitum , and by demand feeders, with each treatment comprised of 4 replicate cages.
Final mean weight was significantly lower for the 50% treatment (94.1 g) than for all other treatments (range = 121.8–155.7 g). Final mean biomass per cage ranged from 24.2 to 39.4 kg/m3 , and survival ranged from 98.2 to 99.8%.
Mean specific growth rate was significantly lower under the 50% programed feeding treatment (2.42%/day) than for all other treatments (range = 3.15–3.56%/day) while feed conversion ratios (dry weight/wet weight) were significantly lower under the 50% (1.57) and 70% (1.68) programed feeding treatments than under all other treatments (range = 1.98–2.26). Thus, maximum growth was achieved at feeding rates near satiation while feed conversion was improved at lower feeding rates. Under demand feeding, growth and feed conversion were not significantly different than those of the ad libitum , 100%, and 90% treatments. 相似文献
Final mean weight was significantly lower for the 50% treatment (94.1 g) than for all other treatments (range = 121.8–155.7 g). Final mean biomass per cage ranged from 24.2 to 39.4 kg/m
Mean specific growth rate was significantly lower under the 50% programed feeding treatment (2.42%/day) than for all other treatments (range = 3.15–3.56%/day) while feed conversion ratios (dry weight/wet weight) were significantly lower under the 50% (1.57) and 70% (1.68) programed feeding treatments than under all other treatments (range = 1.98–2.26). Thus, maximum growth was achieved at feeding rates near satiation while feed conversion was improved at lower feeding rates. Under demand feeding, growth and feed conversion were not significantly different than those of the ad libitum , 100%, and 90% treatments. 相似文献
10.
Volden J Wicklund T Verkerk R Dekker M 《Journal of agricultural and food chemistry》2008,56(6):2068-2073
Brassica vegetables are the predominant dietary source of glucosinolates (GLS) that can be degraded in the intestinal tract into isothiocyanates, which have been shown to possess anticarcinogenic properties. The effects of pilot-scale long-term boiling on GLS in white cabbage (Brassica oleracea L. ssp. capitata f. alba cv. 'Bartolo') was experimentally determined and mathematically modeled. Cabbage was boiled, resulting in a dramatic decrease of 56% in the total GLS levels within the plant matrix during the first 2 min. After 8-12 min of boiling, the decrease progressed to over 70%. Progoitrin had an exceptionally higher decline rate in comparison to all other GLS. As boiling progressed the concentration of all GLS continued to decrease at a lower rate for the remaining cooking period. A mathematical model was used to describe the concentration profile of the GLS in the plant matrix, based on leaching of GLS to the water phase due to cell lysis and thermal degradation of the GLS both in the plant matrix and in the water phase. The model described the concentration profiles very well. Estimated lysis and degradation rate constants for white cabbage differed from those reported in the literature for red cabbage. The degradation rate constants found were significantly higher in the plant matrix when compared to those in the water phase for all GLS. Identification of the kinetics of decline of GLS during cooking can aid in designing processing and preparation methods and determining the conditions for the optimal effects of ingestion of Brassicaceae toward cancer prevention. 相似文献