Frozen tuna at different temperatures of nutrients

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Frozen tuna at different temperatures of nutrients

Road Hao Yue Xiaohua Ding Jian-Qiang Wang Yanyu small package majestic St.
Abstract: In this paper, chemical analysis for tuna in the low temperatures were measured nutrients. Fresh tuna were frozen at -18 ℃, -25 ℃, -30 ℃ three different temperatures, each week was determined for its nutritional content. Analysis of moisture, ash, protein, fat content and storage at different temperatures to the time. In the six weeks at different temperatures, moisture and ash content remain basically unchanged, protein content decreased slightly due to protein denaturation. Fat in -18 ℃ and -30 ℃ basically unchanged under the first 5 weeks, 6 weeks measured value is too large. Keywords: Moisture Ash Protein frozen tuna fat
Tuna fish easily browning, the meat frozen at -20 ℃ more than 2 months, the meat from red to dark red, red brown, brown red, brown change, fat is also vulnerable to oxidation. Tuna sashimi become increasingly popular, so the tuna is also getting higher and higher quality requirements. Between tuna from capture to consumption, but also through the storage, distribution, transportation, and sale of distribution, and finally reached the hands of consumers whether to maintain good quality, depending on the time, temperature and experience, that is, the conditions determined by the T-TT , in T-TT studies identified the main sensory evaluation methods used, and the determination of the physical and chemical methods, for most of the frozen foods are in line with the concept of T-TT, the lower the storage temperature of frozen food quality changes more small, practical storage period is also greater. Because of refrigeration technology, economy and people's living habits and other factors tuna sold in China is not very wide, with the technology and the improvement of people's living standard has gradually been accepted tuna.
According to search, study abroad as early as tuna has already begun in the last century, China is still not the current three-T curve of tuna research projects, but also further filling of tuna in the T curve of the three. . This article focuses on the use of physical and chemical methods of tuna as part of the three T curve (tuna, nutrients) to study, to be able to figure out what storage temperature, the tuna can maintain the quality of the longest storage time, in order to better practice for to solve production problems in practice, more widely will be our tuna products are sold home and abroad.
1. Materials and methods
1.1 Experimental Materials
Yellow fin tuna. (TUNA) was purchased from Shanghai Fisheries Jiangpu City, flown in from Fiji transit through South Korea. Tuna according to different demands of different parts of the split, each split into blocks of about 100g, each with 1 were stored at -18 ℃, -25 ℃, -3 0 ℃ three different temperatures before each use be carried out to thaw.
1.2 experimental equipment
Oven; fat fast extraction equipment; Kjeldahl automatic nitrogen analyzer; digestion furnace; mortar; weighing bottle; crucible; crucible tongs; muffle furnace; electronic balance; refrigerator (3 units); cutting board; tool
1.3 Experimental Methods
1.3.1 Determination of water (atmospheric pressure drying method) [1] [2]
Water content is the quality of organic agricultural and livestock organizations and the determination of one of the most basic.
X 1 = (M 2 -M 3 / M 1 -M 3 ) × 100
Where: X 1 ----- sample moisture content%
M 1 ----- weighing bottle and sample the quality of the g
M 2 ----- weighing bottle and dry sample mass g
M 3 ----- weighing bottle quality g
1.3.2 Determination of ash (dry ash method)
1.3.2.1 Principle: total ash is the minerals and salts in food or other miscellaneous things in a certain temperature burning of organic matter in the sample after oxidation, the weighing of residual white matter, which may total ash weight.
1.3.2.2 Instrument
Muffle furnace crucible dryer electronic balance (135 ℃ suitably dried after 2-3 hours of color silica gel as a desiccant, the sample is appropriate for fats and oils such as phosphorus pentoxide of highly hygroscopic desiccant.)
X = (M 1 -M 2 ) / (M 3 -M 2 ) × 100
Where: X ---- ash content of samples%
M 1 --- the quality of crucible and ash g
M 2 --- crucible quality g
M 3 --- crucible and sample the quality of the g
1.3.3 Determination of protein (Kjeldahl method) [ 3] [4]
Protein content (%) = N × (V 2 -V 1 ) × 0.014 / W × K × 100
Where: N ---- standard solution of hydrochloric acid concentration of
V 1 --- Blank consumption volume of standard hydrochloric ml
V 2 --- like droplets given the amount of hydrochloric acid consumed in standard ml
W --- the weight of sample g
0.014-1mmol hydrochloride grams of nitrogen equivalent to g
K --- conversion factor is generally 6.25
1.3.4 Determination of fat: (Soxhlet extraction method)
X = (M 1 -M 0 ) / M 2 × 100 formula: X ---- Sample fat content%
M 0 --- extraction cup quality g
M 1 --- extraction cup and fat mass g
M 2 --- sample quality g
2. Results and discussion
2.1 frozen tuna moisture content at different temperatures results
Figure 1 tuna frozen water content at different temperature curves
Can be seen from Figure 1 in the frozen water content at -18 ℃, -25 ℃ and -30 ℃ six weeks after the next general remain the same.
This experiment measured the water temperature in the next three after 4 weeks did not change much under the same temperature in the three different storage times did not change much, according to the curve of water can be seen in within six weeks of hard to see just a water change, because the storage time is too short on the one hand, on the other bag with fresh, dry place to reduce the possibility of consumption, and therefore the same time, frozen moisture content at different temperatures is basically unchanged.
According Begona Ben-gigirey, Juan M.vieites Baptista De Sousa, Tomas G. Villa, and Jorge Barros-velazquez (1999) Changes in -18 ℃ water 9 months of storage significant change after 12 months After the reduction of water is relatively large. [5]

2.2 frozen tuna Determination of ash at different temperatures, the results
Figure 2 tuna frozen at different temperatures curves of ash content
Minerals and salts ash residue after burning, ash and trace elements in constant, these elements in the maintenance of normal physiological function of the body to protect human health, and so has special significance. Coexistence of minerals and protein to maintain the osmotic pressure of the organizations to form a buffer system to maintain the acid-base balance. During frozen storage of minerals in very small changes, but the occasion of the thawed juice together with the loss. The food industry, ash is an important indicator of quality [6] . It can be seen from Figure 4 of ash in the frozen -18 ℃, -25 ℃ and -30 ℃ little change in the first 4 weeks, indicating that there is no minerals and salts lost with the juice. In the first 5 weeks were tested among a slightly upward trend in temperature, in the under -25 ℃ and -30 ℃ -18 ℃ rise rate of increase than the obvious reason is due to the time when the carbonization or charring charring temperature of less than requirements, so that The measured value is high. It can be seen from Figure 4 at different temperatures within six weeks of ash small changes, so that ash is not within six weeks longer with the storage time and storage temperature decreased and losses.
2.3 tuna frozen at different temperatures for determination of protein results
Figure 3 frozen tuna protein content at different temperature curves
Low temperature impact is mainly on protein denaturation of proteins, denatured proteins mainly to the physical and chemical properties change. The protein content is based on the sample conversion of organic nitrogen content of nitrogen derived. It can be seen from Figure 6 protein in six weeks at different temperatures decreased, indicating that the protein may be due to variability in the decomposition of this period so that some loss of organic nitrogen into inorganic nitrogen, which led to a loss of protein nitrogen. In the frozen 3 weeks and 4 weeks under three temperature values decreased protein content higher, indicating that the protein in frozen storage for 3 weeks beginning degeneration caused by the protein content decreased. It can be seen under the curve decreased with temperature, the protein also reduced the amplitude measured value, indicating that the lower the temperature the smaller the protein content. Therefore, the curve can be seen under the content, protein content with the storage at different temperatures have decreased slightly prolonged.
2.4 tuna frozen fat at different temperatures measured results
Mainly due to changes in fat, fat rancidity, because one is due to biological tissue and microbial enzymes cause hydrolysis to produce free fatty acids. Second, because the air under the action of light and water, the occurrence of hydrolysis and oxidation of unsaturated fatty acids to their increase in peroxide. Fish meat of unsaturated fat than unsaturated fatty acids, therefore the fat oxidation, decomposition is easier, and thus easy to make quality degradation [7] .
Figure 4 tuna frozen fat content at different temperature curves
Fat oxidation by oxidase, catalase caused by the role. Hydrolysis of fat tuna,[link widoczny dla zalogowanych], mainly due to the role of phospholipase caused.
This experiment measured the fat in -18 ℃ and -30 ℃ for 5 weeks under the frozen storage did not change much remained unchanged, indicating that the fat has not changed. Week 6 is too large when measured values of fat oxidation that fat start. -25 ℃ for determination under the fat determination than under -30 ℃ -18 ℃ and fat values are relatively large, for unknown reasons.
3. Conclusion
The experimental results show that: water ﹑ ash in 6 weeks does not change with storage time and temperature changes, not vary with time changes, nor with the deepening of the storage temperature changes much. 6 weeks in storage proteins, the three temperatures are slightly down, the lower the temperature decreased more slowly. Fat in -18 ℃ and -30 ℃ under essentially the same content in the first 5 weeks, 6 weeks, the high measured value, -25 ℃ -18 ℃ measured values are generally higher than the measured value and under -30 ℃.
References:
[1] Food Analysis Chemical Industry Press, edited by Houman Ling 2004.6 (3) :21-36
[2] the quality of agricultural and veterinary chemical analysis of aquatic products editor Dan Bao Shi China Agriculture Press 1996.7 (3) :119-120
[3] Chen Xuanjie Analytical Chemistry editor of Higher Education Press, 1995.3 (3) :64-66
[4] Huang Weikun Food Inspection and Analysis, edited by Light Industry Press 1989.1 (2) :8-10; 17-18; 25-28; 48-54
[5] Chemical changes and visual appearance of albacore tuna as related to frozen storage. Ben-Gigirey,-B; Vieites-Baptista-de-Sousa,-jM; Villa,-TG; Barros-Velazquez,-Journal- of-Food-Science.1999; 64 (1) :20-24; 28 ref.
[6] Aquatic processing integrated technology edited by Lin Yu Qian Wang Tao Yang Fengguang 2003.1 (3) :55-61
[7] ALPHA frozen food of a quality management editor of Shanghai Jiaotong University Press 1990.9 (3) :67-73