Peeled,headed or whole shrimp(Pandalus borealis)was dried in a heat-pump dryer at-2-0℃and 20℃,respectively,and desorption isotherms characterizing the dehydration property of each shrimp sample group were determined...Peeled,headed or whole shrimp(Pandalus borealis)was dried in a heat-pump dryer at-2-0℃and 20℃,respectively,and desorption isotherms characterizing the dehydration property of each shrimp sample group were determined.Desorption isotherms of shrimp handled differently and dried at different temperatures(-2-0℃or 20℃)could be well described by Oswin’s model(X=a(1-a_(w)/a_(w))).The regression model of peeled,headed or whole shrimp was established,which is reliable for predicting the desorption isotherms of shrimp undergoing heat-pump drying.The handling methods of shrimp exhibit measurable influence on desorption isotherms of shrimp,whereas drying temperature(-2-0℃or 20℃)has little influence on the constants of a and n in Oswin’s model,of whole shrimp,even though it has certain influence on these constants of peeled and headed shrimp.For heat-pump drying,headed shrimp may have a better stability than peeled or whole shrimp due to the best stability.展开更多
The size selectivity and usability of three codends were quantified and compared for the first time in the inshore Northern shrimp(Pandalus borealis)trawl fishery of Iceland using the covered codend method:a conventio...The size selectivity and usability of three codends were quantified and compared for the first time in the inshore Northern shrimp(Pandalus borealis)trawl fishery of Iceland using the covered codend method:a conventional diamond-mesh codend(T0),conventional square-mesh codend(T45),and a 90◦turned mesh codend(T90)constructed of four panels and with shortened lastridge ropes.Fishers,wanting to increase the average-individual size of captured shrimp,had requested the T90 codend to be compared with conventional codends for consideration in the fishery.Results showed that,on average,the T45 and T90 codends had better size selectivity than the T0 codend in terms of releasing individuals smaller than 13 mm carapace length(Minimum References Size;MRS).The T90 codend retained significantly less Northern shrimps between 9 and 19 mm than the T0 codend and between 15 and 19 mm than the T45 codend.No significant difference of size selectivity between T45 and T0 codends was observed.All three codends presented high retention ratios of Northern shrimps above MRS(>63%)for the population encountered.However,the T0 codend was not effective at sorting out small Northern shrimps;at least 86%of Northern shrimps smaller than 13 mm were retained in the T0 codend if encountered.Catches from T45 and T90 codends had a lower proportion of shrimp below MRS.Since discarding of undersized Northern shrimps is prohibited in Iceland and fishers wanted to catch on average larger shrimp,using the novel T90 codend would enable fishers to use their quotas more efficiently.展开更多
Shrimps are the most consumed species among crustaceans and are well appreciated for their flavor and high nutritional value. This work investigated the antioxidative compounds of Northern shrimp (Pandalus borealis) a...Shrimps are the most consumed species among crustaceans and are well appreciated for their flavor and high nutritional value. This work investigated the antioxidative compounds of Northern shrimp (Pandalus borealis) and its processing discards (shells and heads) using various solvents and chromatographic techniques as well as mass spectrometry. Ethanol served as the best extraction medium, and the extracts obtained demonstrated strong antioxidant activity in a β-carotene-linoleate emulsion system. The antioxidative compounds of the extract were isolated using a silica gel column chromatography, followed by thin layer chromatography. This led to the identification of two highly polar and two low polarity compounds. These compounds, for the first time, were isolated and purified by using reversed-phase HPLC. Their structures were tentatively elucidated using electrospray mass spectrometry. These unique compounds were heterocyclic phenolic compounds and identified as 7-(3-butenyl)- 2-hydroxy-6-(1,2,5,6-tetrahydropyridin-2-yl) quinoline and 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tertahydropyridin-2-yl)- 7,8-dihydroquinoline and their isomers. The proposed novel compounds in shrimp provide a reason for their oxidative stability and potential benefits, as well as possibly serving as substrates for the discoloration of shrimp.展开更多
文摘Peeled,headed or whole shrimp(Pandalus borealis)was dried in a heat-pump dryer at-2-0℃and 20℃,respectively,and desorption isotherms characterizing the dehydration property of each shrimp sample group were determined.Desorption isotherms of shrimp handled differently and dried at different temperatures(-2-0℃or 20℃)could be well described by Oswin’s model(X=a(1-a_(w)/a_(w))).The regression model of peeled,headed or whole shrimp was established,which is reliable for predicting the desorption isotherms of shrimp undergoing heat-pump drying.The handling methods of shrimp exhibit measurable influence on desorption isotherms of shrimp,whereas drying temperature(-2-0℃or 20℃)has little influence on the constants of a and n in Oswin’s model,of whole shrimp,even though it has certain influence on these constants of peeled and headed shrimp.For heat-pump drying,headed shrimp may have a better stability than peeled or whole shrimp due to the best stability.
文摘The size selectivity and usability of three codends were quantified and compared for the first time in the inshore Northern shrimp(Pandalus borealis)trawl fishery of Iceland using the covered codend method:a conventional diamond-mesh codend(T0),conventional square-mesh codend(T45),and a 90◦turned mesh codend(T90)constructed of four panels and with shortened lastridge ropes.Fishers,wanting to increase the average-individual size of captured shrimp,had requested the T90 codend to be compared with conventional codends for consideration in the fishery.Results showed that,on average,the T45 and T90 codends had better size selectivity than the T0 codend in terms of releasing individuals smaller than 13 mm carapace length(Minimum References Size;MRS).The T90 codend retained significantly less Northern shrimps between 9 and 19 mm than the T0 codend and between 15 and 19 mm than the T45 codend.No significant difference of size selectivity between T45 and T0 codends was observed.All three codends presented high retention ratios of Northern shrimps above MRS(>63%)for the population encountered.However,the T0 codend was not effective at sorting out small Northern shrimps;at least 86%of Northern shrimps smaller than 13 mm were retained in the T0 codend if encountered.Catches from T45 and T90 codends had a lower proportion of shrimp below MRS.Since discarding of undersized Northern shrimps is prohibited in Iceland and fishers wanted to catch on average larger shrimp,using the novel T90 codend would enable fishers to use their quotas more efficiently.
文摘Shrimps are the most consumed species among crustaceans and are well appreciated for their flavor and high nutritional value. This work investigated the antioxidative compounds of Northern shrimp (Pandalus borealis) and its processing discards (shells and heads) using various solvents and chromatographic techniques as well as mass spectrometry. Ethanol served as the best extraction medium, and the extracts obtained demonstrated strong antioxidant activity in a β-carotene-linoleate emulsion system. The antioxidative compounds of the extract were isolated using a silica gel column chromatography, followed by thin layer chromatography. This led to the identification of two highly polar and two low polarity compounds. These compounds, for the first time, were isolated and purified by using reversed-phase HPLC. Their structures were tentatively elucidated using electrospray mass spectrometry. These unique compounds were heterocyclic phenolic compounds and identified as 7-(3-butenyl)- 2-hydroxy-6-(1,2,5,6-tetrahydropyridin-2-yl) quinoline and 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tertahydropyridin-2-yl)- 7,8-dihydroquinoline and their isomers. The proposed novel compounds in shrimp provide a reason for their oxidative stability and potential benefits, as well as possibly serving as substrates for the discoloration of shrimp.
