4 resultados para freeze thawing

em Universidade Federal do Rio Grande do Norte(UFRN)


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The objective of the current study was to evaluate the zootechnical performance (survival and growth) of Litopenaeus vannamei post-Iarvae fed an artificial shrimp diet supplemented with Artemia flakes or freeze-dried Artemia embryos. For that purpose, 20 culturing units were individually stocked with 50 shrimp post-Iarvae (average dry weight of 0,3 ± 0,03 mg) at a stocking density of 20 post-larvae per liter, and fed the experimental diets to satiation during 20 days. The experimental design consisted of four diets (T1, T2, T3 and T4) with five repetitions each. For treatments T1, T2 and T3, dietary supplements of 5mg of Artemia flakes (T1), freeze-dried Artemia embryos (T2), and of the commercial shrimp diet (T3) were offered 2 hours after the shrimp were initially fed the commercial shrimp diet. For treatment T4 (control), no additive was offered 2 hours after the initial feeding. Shrimp survival, absolut (GPA) and relative increase in weight (GPR), and specific growth rate (TCR) were used as evaluation criteria. After the experimental period, no significant statistical differences (p>0,05) in survival were observed. Regarding growth, the dietary treatment which used freeze-dried Artemia embryos as an additive (T2) presented the best results for GPA (6,7 ± 0,7 mg). There were no statistical differences within treatments T1, T3 and T4 (p>0,05). AIso, post-larvae fed freeze-dried embryos (T2) showed a relative increase in weight (2241,4%) which differed significantly (p<0,05) from T4(1911,7%) but not from T1 (1801,6%) or T3 (1946,7%). In conclusion, the results of the current study indicate that an artificial shrimp diet supplemented with freeze-dried Artemia embryos fulfils the nutritional requirements of post-larvae L. vannamei and promotes a better growth than diets not supplemented with Artemia flakes

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Brazil, one of the largest agricultural producers in the world, has managed in recent years to significantly improve its production. However, in response to this advance in the agro-industrial sector, the generation of agro-industrial residues has also increased. New technological alternatives have to be implemented in order to bring economic and rational use of this material and drying is one of the possible choices. Considering the great importance that bioactive compounds present for food science and technology, this research aims to evaluate the air-drying process of acerola residue in a tray convective drier under controlled temperature (60, 70 e 80ºC), air velocity (4.0, 5.0 e 6.0 m/s) and material width (0.5, 0.62 e 0.75 cm) by applying an experimental planning 23 + 3. Based on that, the impact on physical-chemical characteristics, color, bioactive compounds concentration and antioxidant activity of dried acerola waste was evaluated, having the in natura and freeze dried waste as control groups. Dried acerola residue presented natural pigments, mainly carotenoids (143.68 - 68.29 mg/g) and anthocyanins (290.92 - 90.11 mg/100 g), which explain the red and yellow instrumental color parameters observed. The acerola residue powder is also rich in phenolic compounds (3261.11 -2692.60 mgGAEeq/100g), proanthocyanidins (61.33-58.46 eq/100g), ascorbic acid (389.44 739.29 mg/100 g) and DPPH antioxidant activity (20.91 24.72 μg Trolox eq/g). Results show decreased concentration of phenolic compounds, anthocyanins, carotenoids, proanthocyanidins and ascorbic acid caused by the air-drying process. However, even after the observed drying losses, the acerola residue powder can be considered a high value food ingredient, considering the high bioactive compounds concentration found in the final product, as well as the colorimetric characterization and microbiological stability of the dried powder

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Tropical fruits have been extensively studied due to their functional potential attributed to the presence of natural bioactive compounds. The exotic fruit jambolan (Syzygium cumini) has been reported for its appreciable amount of phenolic compounds, especially anthocyanins and antioxidant capacity. Nevertheless, there are hardly any derived jambolan products in the Brazilian market. In addition to that, considerable volumes of fruit are lost due to their high perishability. Dried fruits have become an important fruit market segment due to its weight and volume reduction and decreased transportation and storage costs. Thus, this study evaluated the jambolan pulp submitted to spouted bed drying (JLJ) and lyophilization (JLI), besides assessing the drying impact on the final product. In order to achieve this, the process performance was calculated and compared, as well the physicochemical and bioactive characteristics (moisture, water activity (aw), solubility, hygroscopicity, density, color, structure through images obtained by scanning electron microscopy (SEM), concentration of bioactive (total phenolic compounds (TPC), anthocyanins, proanthocyanidins and ascorbic acid) and antioxidant activity. The results showed drying efficiency higher than 60% for both products and that JLJ group showed higher moisture and water activity when compared to the JLI group (p<0.05). The two types of drying were able to produce stable final product in the microbiological point of view, given that both showed aw < 0.6. The final products exhibited high solubility (73.7 to 81.6%) and low hygroscopicity (9.8 to 11.6%), desirable characteristics for dehydrated foods. Despite the losses caused by drying, the dried jambolan pulp by both methods showed high TPC (468.6 to 534.0 mg GAE/100g dm), anthocyanins (from 491.9 to 673.4 mg. eq. cyanidin-3-glicoside/100g dm), proanthocyanidins (66.9 to 76.6 mg QTE/g dm) and ascorbic acid (156.4 to 186.8 mg/100 g dm). Taken together, the results of this study reveal spouted dried and freeze dried jambolan pulp as bioactive-rich natural products with suitable physicochemical and functional characteristics to be used as food ingredients. The data also demonstrate the drying techniques as rational strategies for the exploitation of the exotic fruit jambolan

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In this study, we worked with the validation of a methodology for analysis of bioactive amines in shrimp, considering it to be one of the main products of the northriograndense trade balance, maintaining the state of Rio Grande do Norte topped the list of Brazilian exports of this product the last decade. The sector of the Brazilian shrimp works exclusively with gray shrimp Litopenaeus Vannamei since the late 1990s. This study used liquid chromatography with conductimetric detector, using as the mobile phase methylsulfonic 3 mM acid (MSA) with gradient and phase C18 column with reverse the development of methodology for the analysis of bioactive amines in shrimp. In the sample preparation was used as 5% trichloroacetic acid (TCA) extraction solution. Validation analysis of biotativas amines (putrescine - PUT, histamine - HIST, agmatine - AGM, spermidine - EPD and spermine - EPN) in shrimp, the linear working range was 0.1 to 2.0 mg L-1 to was sensitive, homoscedastic, in effect, selective, accurate and precise array. Thus, considered feasible for these determinations bioactive amines in this array. Determined the concentration of these amines in fresh shrimps (AGM = 0.61 ± 0.05 mg kg- 1 EPD = 2.57 ± 0.14 mg kg-1 and EPN = 1.79 ± 0.11 mg kg-1), and freezing weather predetermined in cooked shrimp (AGM = 6.28 ± 0.18 mg kg-1, EPD = 12.72 ± 0.02 mg kg- 1 and EPN = 22.30 ± 0.60 mg kg-1), the shrimp with twenty-four hour stay at room temperature (PUT = 879.52 ± 28.12 mg kg-1, AGM = 848.13 ± 19.40 mg kg-1, ESPD = 13.59 ± 0.97 mg kg-1 and ESPN = 18.47 + 1.57 mg kg-1). In shrimp subjected to freezing for a week, two weeks, three weeks and four weeks, the results showed that there is an increase in the content of agmatine (7.31 ± 0.21 mg kg-1) while in spermine ( 1.22 ± 0.14 mg kg-1) and spermidine (below limit of quantification) there was a decrease in the freeze time, while there is a decrease in the level of spermidine not reaching detectad. The putrescine was only found in shrimp that remained for 24 hours at room temperature and histamine was not found in any of the samples