Long-Term Frozen Storage Impact on the Antioxidant Capacity and Chemical Composition of Sardinian Myrtle （Myrtus communis L,） Berries

The effects of frozen storage at -18 ℃ up to 6 months, on the antioxidant properties, chemical composition and other physicochemical properties of myrtle berries （Myrtus comrnunis L.） has been evaluated. Berries showed a good resistance to storage decay, and weight loss remained after six months in the 15% range. Results showed that frozen storage up to 6 months affect individual antocyanins content in different ways. Nevertheless the total anthocyanins content was at the end of storage higher than in fresh fruits. The antioxidant capacity calculated with 2,2-diphenyl-l-picrylhidrazyl （DPPH） and 2,2＇-Azino-bis （3-ethylbenzothiazoline-6-sulfonic acid） （ABTS） increased during storage and the calculated r2 showed a positive correlation with the total anthocyanins content. Gluconic and fumaric acid did not changed, quinic acid decreased while malic and shikimic acid increased. The total organic acid content during storage was higher than in fresh fruits causing a slight decrease in pH. Fructose and glucose increased with the same rate and the ratio fructose/glucose remained unchanged （1.06 ± 0.01）, CIE L^＊a^＊b^＊ coordinates showed a shift of the colour to tawny brown after six months storage.

Influence of Frozen Storage Time on Unsaturated Fatty Acids and Proximate Composition of Caspian Sea White Fish （Rutilus frisii kutum） Fillets

The main aim of this research was to identify fatty acids composition of Caspian Sea of white fish Rutilusfrisii kutum tissue and their changes during 12 months storage （-18 ℃ ）. The results showed, UFA （Unsaturated Fatty Acid） and SFA （Saturated Fatty Acid） were 74/09 and 21/63%, respectively in fresh tissue. So that, DHA （C22：6） oleic acid （C 18：1c） had high amounts （15/07, 20/57） UFA and palmitic acid （C16：0） was the most （13/09%） SFA. The effects of freezing on fish tissue showed that UFA and SFA contents have reached to 58/79 and 22/17%, respectively at the end of cold storage. Also ω-3 and ω-6 series of fatty acids was 24/22 and 15/56% in fresh tissue, but their contents decreased to 8/68 and 5/11% at the end of period. Among, the fatty acids C22：6, C 18：1 c and C 16：0 had the most changes. The changes of fatty acids were significantly at 95% level expected for C18：0.

Effects of frozen storage on texture,chemical quality indices and sensory properties of crisp Nile tilapia fillets

Crisp Nile tilapia(Oreochromis niloticus)is a kind of valuable fish product with high muscle firmness and crispiness texture.However,with the change of physicochemical in crisp Nile tilapia,the frozen storage parameters and quality would be different comparing to normal Nile tilapia.Thus,the aim of this study was to analyze the changes in texture,chemical quality indices and volatile compounds of Nile tilapia fillets during frozen storage.The remaining storage time of the crisp Nile tilapia fillets could be estimated within 120 days.During frozen storage,fillets resulted in softer started at 90-day,and 36.75%,45.74%,48.81%and 20.37%reduction of hardness,springiness,gumminess and chewiness were observed at 120-day.Thiobarbituric acid reactive substances(TBARS)for frozen samples showed similar with fresh fillets within 60 days,while the TBARS was 1.97 folds higher than fresh one at 120-day.Low-field nuclear magnetic resonance(LF-NMR)indicated that the water loss of Nile tilapia fillets was significant changed at 120-day,which reduced more than 12.5%water out of weight.The volatile compound analysis showed that more free fatty acid will be detected at 120-day comparing to the fresh fillets.The combined results demonstrated that the crisp Nile tilapia fillets had the best quality before 60 days frozen storage then loss of some quality properties in longer freezing.Thus,these results identified the ideal storage strategy for the preservation of crisp Nile tilapia without affecting sensory appeal and commercial value.

Biquinho pepper(Capsium chinense):Bioactive compounds,in vivo and in vitro antioxidant capacities and anti-cholesterol oxidation kinetics in fish balls during frozen storage

The present study reports bioactive constituents from biquinho pepper,such as carotenoids,capsaicinoids,and capsinoids,identified by UHPLC-MS.Biquinho pepper extract showed an antioxidant potential by DPPH(33.17±0.08%),ORAC(32.35±0.02μM TE/g),β-carotene/linoleic acid(55.80±1.30%),and FRAP(315.88±4.23μmol TE/g)assays.Additionally,in vivo antioxidant analyses demonstrated that the pepper extract(170μg/mL)decreased the damage promoted by H_(2)O_(2) in Saccharomyces cerevisiae cells.Fish balls were prepared using different concentrations of pepper(0.0%,0.5%,0.75%,1.0%)to investigate its antioxidant effect during frozen storage.Biquinho pepper effectively reduced the formation of cholesterol oxides and preserved essential fatty acids,mainly in samples containing 1.0%of pepper.Moreover,this treatment was more efficient than sodium erythorbate(p<0.05),which was used as standard.The kinetics of cholesterol oxidation was also determined,showing that both cholesterol degradation and cholesterol oxides formation fit a first-order kinetic model(R^(2)>0.8).

Physicochemical properties of silver carp(Hypophthalmichthys molitrix)mince sausages as influenced by washing and frozen storage

Frozen storage of emulsion-type sausages may be one approach to avoid or reduce the use of sodium nitrite,which is associated with health risks.Silver carp(Hypophthalmichthys molitrix)mince(M_(0))was washed for 1(M_(1))or 3(M_(3))times and the impact of washing on the properties frozen storage(−18℃)during 4 months were determined and results were compared to those of conventional silver carp sausages(Mt).Lipid oxidation,as evidenced by changes in thiobarbituric acid reactive substances and FFAs,took place during storage in the order of M_(0)>M_(1)=M_(3)=Mt with M_(0)being highly oxidized(P≤0.05).Total volatile base nitrogen formed during storage and the ranking for the quality loss was as follows M_(0)>M_(1)>M_(3)=Mt.Washing(M_(1)=M_(3))led to less hardness(P≤0.05).Mt had better redness,while M_(1)and M_(3)led to higher expressible moisture,water release and lightness(P≤0.05).Results indicated the lower sensory and consumer-liking properties of frozen M_(1)and M_(3)sausages.Therefore,washing and frozen storage influenced silver carp mince sausages.

Effect of Glutathione and Storage Time on Rheological Properties of Per-proofed Frozen Dough

The effect of reduced glutathione (GSH) on fresh and pre-proofed frozen dough rheological properties were investigated using dynamic stress rheometry and small scale extensibility with the addition of three levels (80×10-6, 160× 10-6 and 240×10-6 GSH) and six storage times (0 and 1 day, 2, 4, 6 and 8 weeks). Three relaxation times (1, 13 and 26min) after loading the dough in the rheometer were used to determine storage (G’) and loss (G”) moduli. Correlations for G’ (r=0.678 and 0.622 at 0.05, and 10Hz, respectively) and G” (r=0.699, and 0.690 at 0.05, and 10Hz, respectively) were observed with the area under the extension curve at 26 min relaxation time. The addition of GSH to fresh dough reduced G’ (16.4% to 55.9%) and G” (13.7% to 52.2%). Freezing and frozen storage caused increase in G’ and G”. The addition of GSH reduced dough strength indicated by the reduction in maximum resistance to extension (Rmax) and the ratio of maximum resistance to extensibility (Rmax/E). The reduction in Rmax across all relaxation times ranged from 16.2% to 59.4%. An increase in dough extension (E) was observed with 240×10-6 GSH at all frozen storage and rest period times. Addition of GSH caused an increase of liquid phase (30.6% to 35.3%) in fresh dough and frozen dough (10.3% to 20.7%) after one day frozen storage. Negative correlations of water content in the solid phase with dough extensibility and area under the extensibility curve were found (r=-0.594 and-0.563, respectively, p<0.001). This suggests a loss of dough extensibility and strength as the water holding capacity of the dough components changes during frozen storage.

Quality Assessment of Frozen Solenocera crassicornis Treated with Sodium Metabisulphite by Soaking or Spraying

The present work was carried out to evaluate the safety of shrimp(Solenocera crassicornis)treated with different concentrations of sodium metabisulfite(SMB)by soaking or spraying during frozen storage.Shrimps soaked in higher concentrations of SMB showed higher sensory scores,lower total color differences,and better anti-melanosis effects than shrimps in the control and other treatment groups throughout frozen storage(−18℃).Lower total volatile basic nitrogen and thiobarbituric acid reactive substances and higher salt soluble protein contents were detected in shrimp soaked with high doses of SMB compared with other samples.In addition,lower counts of total aerobic plates and psychrotrophic bacteria were observed in shrimp treated by soaking with higher doses of SMB than those in control shrimp and shrimp treated with other methods during frozen storage(−18℃).However,the SO2 content of 5%SMB-soaked samples exceeded the maximum allowable limit of 100mgkg−1.Overall,the use of 1.5%SMB soaking to treat shrimp results in good antioxidant and antimicrobial effects and,thus,may be suggested to preserve S.crassicornis under frozen conditions.The results of this study present important guidance on the use of SMB to maintain the quality of marine-trawling shrimp from manufacturing to consumption.

New insight into the contribution of wheat starch and gluten to frozen dough bread quality

The contribution of starch granules to the baking properties of frozen dough bread has been investigated using reconstituted dough method.The baking and aging characteristics of frozen dough bread were studied by texture analyzer,colorimeter,DSC,FTIR and LF-NMR.Results showed that starch had more impact on bread than gluten in specific volume of frozen dough bread,while gluten contributed more in color and cell density of frozen dough bread crumb during 8-weeks frozen storage.The changes of hardness mainly contributed to starch deterioration in first 4 weeks,then it was dominated by gluten in the later 4-8 weeks.A-Type granules have more effect on texture properties,number of cells and enthalpy of frozen dough bread during storage.B-Type granules contributed more on the size of cells in bread.The main aging change of wheat starch in profiles of bread was provided by A-Type granules during frozen storage.

Oleuropein from Olive Leaf Extract as Natural Antioxidant of Frozen Hamburger

Oxidation is one of the major causes of hamburger deterioration. Antioxidants are used to minimize oxidation process. There is a growing interest in the substitution of synthetic food antioxidants by natural ones from vegetable sources. In meat industry, sodium erythorbate is antioxidant that is usually used and is an example of chemical antioxidant. Effect of olive leaf extract rich in olenropein on the quality of frozen hamburger was investigated. The objective of this study was to evaluate the usage of oleuropein from olive leaf extract as natural antioxidant in frozen hamburger stored at -12 ℃ compared with sodium erythorbate. Results suggested that olive leaf extracts might be useful to the meat industry as an efficient alternative to synthetic antioxidants by retarding oxidation of hamburger compared with sodium erythorbate 0.5% of olenropein and 0.5% of sodium erythorbate are the best concentrations to be used in frozen hamburger.