At present, the domestic frozen seafood preservation method is often used, but requires refrigeration equipment, and in transportation, sales process have to be equipped with the "cold chain", which not only improves the product's cost, but also affect the expansion of its sales outlets; while With people's living standards improve, because the taste of frozen aquatic products dropped, has become increasingly from consumers. Research a cost-effective way to extend the state of preservation of fresh fish shelf life has important economic and social value.
Fish in the preservation process produces corruption, mainly by micro-organisms, the role of enzymes in meat and fish exposed to the air so that oxidation due. Wherein the microorganism is the main reason lead to corruption. If elimination or reduction of microbial and enzyme activity, we can achieve the purpose of storage and preservation.
Microwave is the wavelength of the electromagnetic wave between 1mm ~ 1m, the use of microwave energy for the sterilization of food preservation is the world's rapid development of a new technology. The principle is that the bacteria in the microwave electromagnetic field by the electromagnetic effect, resulting in a response effects of electromagnetic effects, then the survival of the bacteria in the exchange with the outside membrane ion channels closed nutrients, disturbed normal physiological activities come to a halt, causing the cell membrane moment of rupture; Meanwhile, food absorb microwave energy after its rapid rise in temperature, the microbial protein two, three structural damage, and thus play a role in killing microorganisms.
Furthermore, since the microwave energy to the food material is heated directly, the rapid heating, processing time three products, it can maintain the nutrients, flavor, color and so on. In this paper, the characteristics of microwave sterilization, microwave energy is used to investigate the state of preservation of fresh octopus segment effect on the state of the domestic fresh fish preservation methods to explore. I. Materials and Methods 1, octopus segment sources and treatment
Fresh market products octopus, eyes protruding, Yinlin more and shiny, red gills, no belly turn, a weight of about 500 grams, to the head, tail, dorsal fin, internal organs, cleaned, cut into about 150mm The long, loaded nylon - polyethylene bags, bagging requires octopus spliced ​​less than 5mm, each bag weighs 250g ± 10g, and then use the vacuum packaging machine in sealed packaging under vacuum 650mmHg spare. 2, microwave sterilization test
Fish like the above small package with a microwave oven microwave processing, microwave technical performance are: microwave power 750W, operating frequency is 2450MHz. 3, sensory evaluation
Press the iced seafood like fish freshness standard assessment of the sensory indicators. 4, volatile basic nitrogen
Measured by micro-diffusion method. 5, the determination of the total number of bacteria
30 ℃ incubator using nutrient agar medium was incubated for 48 hours, plate count. Second, the results and discussion a microwave intensity time determination in dealing with
Packed in 250g ± 10g octopus section for testing, in order to maintain fish with fresh state of preservation, octopus highest surface heating temperature should <℃. To this end, in 45 ℃ basis of microwave radiation of longest processing time. Tests showed that the 750W microwave intensity, the longest processing time is 84S (octopus segment initial temperature of 14.5 ℃). 2, the choice of the optimum conditions of microwave sterilization
By orthogonal table L9 (34) arranged two factors and three levels of amber cross test in which the maximum value of the power maximum radiation intensity microwave radiation maximum time period of the preceding octopus fresh state retention requirements determine the level of factors specific arrangements see Table 1. Table 2 shows analysis of variance, two factors in order of A> B, optimal sterilization conditions are A3B3, i.e. the microwave power is 750W, kill time is 80S. 3, microwave sterilization fish samples after storage change
The optimum conditions of microwave sterilization test samples with the control group placed in the same storage under natural conditions, the timer record early in the evening daily indoor temperature, time observation and determination of two meat-like.
① storage room temperature changes
② sensory evaluation results
Table 4 shows the test group the indicators are in the first 13 days storage of mild changes, while the control group, only store three days have significant adverse changes to the first five days has been unable to eat.
③ T-VBN determination
Tests showed that the experimental group saved 15 days after T-VBN value is only 15.2mg/100g, while the control group had more than the first five days 20.0mg/100g, change its look and feel changes with T-VBN values ​​are in good agreement. Third, the Discussion 1, with the increase of intensity of the microwave or the extension of time, octopus section can be increased, although the effect of sterilization, fresh state at room temperature may be prolonged time saved, but the role of the effects of microwave energy to heat aging octopus. Therefore, the state of preservation of fresh octopus segment of its microwave irradiation time not too long. However, the duration of microwave treatment only microwave intensity (meat temperature <45 ℃), simultaneously with the use of microwave frequencies and increase the amount of speculation about things. Microwave intensity in the same process, with the added amount of the inlet increases, the exposure time is multiplied to long. Further, in the industry, can be 915MHz microwave frequency processing, because a strong penetration, the relative microwave irradiation time may be extended to improve the non-thermal effects of microwave energy sterilization. 2, with a low intensity microwave treatment 2450MHz nylon - polyethylene plastic vacuum packaging octopus segment, fresh state at room temperature, saving more than 10 days may be extended, the effect is very obvious.
Rapid microwave heating uniformity, the processing time is short, for octopus flavor, color, etc. without adverse effects, is a safe, hygienic preservation technology. Although its fresh state of preservation time is not long, but if combined with preservative used in conjunction, is expected to save the state at room temperature, fresh 2-3 months for the future by microwave processing of fresh fish on the market has laid a good foundation.

 

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