Patent Application
20070062155
1. Field of the Invention
The present invention relates to a packaging method for removing off-odors from irradiated foods using charcoal.
2. Description of the Prior Art
Charcoal a blackish, light, porous material comprising about 70% to 90% carbon, the remainder consisting of volatile chemicals and ash, and resembles coal obtained by removing water and other volatile constituents from animal and vegetable substances. It is usually produced by heating wood, such as that of oaks, quercitrons, chestnut trees, larch, pine trees, cryptomeria, cypress, bamboos, plum, big cone pine, or mulberry trees. However, chaff charcoal, palm tree bark charcoal and others can be produced as well. Depending on the degree of carbonization, charcoal is divided into low temperature charcoal, carbonized at 400-500° C., such as dry distillation coal, open-hearth furnace coal, etc., medium temperature charcoal, carbonized at 600-700° C., such as black coal, and high temperature charcoal, carbonized at around 1,000° C., such as white coal.
The woody parts of plants are the source of charcoal. When heated, cellulose, hemicellulose, lignin, and other components found in the woody parts are suddenly decomposed at around 280° C. into their constituting elements, such as carbon and hydrogen, in an anoxic or suboxic condition, with the concomitant production of various gases, such as carbonate, carbon monoxide, hydrogen, hydrocarbons, etc. As the temperature increases, carbon becomes abundant and amorphous. When the heating temperature reaches 650-700° C., the woody parts have greatly diminished content of oxygen and hydrogen, with a great change in surface properties. The carbon content is 50% in fresh wood and increases to 72% upon carbonization at 400° C., 89% at 600° C., and 95% or more at 1,000° C. Charcoal is found to have a number of micropores when observed with a microscope. In fact, charcoal has a surface area as large as about 300 m2 per gram.
The carbon atom, a major constituent of charcoal, has 6 protons in the nucleus and 6 electrons, with 4 valence electrons in the outermost orbital thereof, and has low reactivity so that it neither loses nor gains electrons easily. Meanwhile, because charcoal has free electrons remaining unbound to atoms, it is electrically conductive and can form a magnetic field so as to provide electrons to the immediate surroundings. In addition, charcoal contains a large amount of minerals to keep the adjacent environment in a negative ion state. These anions emitted from charcoal increase the voltage across cellular membranes, allowing waste substances to be discharged from cells. In addition to five major minerals, such as calcium, potassium, iron, phosphorus, and sodium, charcoal contains copper, zinc, manganese, magnesium, chrome, molybdenum, etc., which are useful for aging prevention, blood coagulation prevention, and recovery from fatigue. Charcoal is a potent far infrared radiator whose infrared rays can minutely vibrate water and protein molecules at a frequency of 2000/min. Thus, when exposed to such infrared rays, cells are activated to promote cellular metabolism and spontaneously discharge waste substances therefrom.
In addition, charcoal shows an anti-microbial and anti-oxidant activity to inhibit the growth of microorganisms and a reduction activity to improve the freshness of neighboring materials. Charcoal also has various functions such as purifying water, generating anions to filter air, absorbing positrons, which are odorizing factors, to remove unpleasant odors, and eliminating toxic materials, such as nicotine, and pollutants, such as automobile emissions, agricultural chemicals, etc. Thus, charcoal is finding application in various fields, including those of food, agriculture, industry, environmental engineering, health, applied fine arts, etc.
There are many patents that utilize charcoal. For example, Korean Pat. No. 319791 discloses a pillow which comprises charcoal as the stuffing thereof, asserting that it provides the user with a pleasant and healthy sleep and absorbs secretions from the user, such as sweat, to prevent the production of bad odors and the inhabitation of pathogens.
Korean Pat. Laid-Open Publication No. 2001-0104010 discloses an antibacterial resin composition superior in keeping foods fresh, made from a ceramic composition in combination with at least one selected from among illite, sericite, vermiculite, ocher, kaolinite, charcoal, jade, serpentine, germanium and elvan.
Irradiated foods are foods that are irradiated with energy from radioisotopes or electron, such as gamma rays (Co-60 or Se-137), X-rays, and accelerated electrons etc., that is, ionized radioactive energy at a dose from 1 kGy to 100 kGy. The radioactive irradiation is intended to kill pathogens, such as microorganisms, parasites, harmful insects, etc., to sterilize foods without changing the original food properties, and to suppress the germination of foods and slow the aging of foods. A variety of chemicals have been used to kill harmful bacteria and fungi present in foods, but may cause fatal injury to human bodies and destroy the environment. In most advanced countries, irradiation is widely used to sterilize foods for economic benefits and safety reasons.
Irradiation is generally known as an economical and safe method for sterilizing and preserving foods and public hygiene products for an extension of shelf-life without increasing product temperature. With research on modified starches irradiated with gamma rays, Kang et al. reported that gamma irradiation was advantageous in terms of process control, rapidity and, accuracy, energy efficiency, and consumer acceptance [Kang I J, Byun M W, Yook H S, Bae C H, Lee J H, Kwon J H, Chung C K. Production of modified starches by gamma irradiation. Radiat. Physics. Chem. 54: 425-430 (1999)]. When irradiated at up to 1 kGy, foods are reported to have nutrients that are not influenced thereby, but that are substantially identical to those of non-irradiated foods. Factors influencing nutrients of foods upon irradiation are reported to include dose, temperature, presence with oxygen, and storage conditions. Upon 1 kGy or higher irradiation, vitamins are somewhat destroyed at high-temperatures or in the presence of oxygen, but this depends on the kind thereof. Generally, vitamin loss can be prevented by low temperatures in the absence of oxygen. Minerals are not affected by irradiation. Carbohydrates; lipids and proteins are found to undergo no degradation with 10 kGy irradiation, and to only slightly degrade upon irradiation as large as 50 kGy.
However, one of the main problems with irradiated foods is the production of off-odors due to lipid oxidation and protein degradation. Off-odors, known to result from the oxidation of free radicals occurring during irradiation, acts as a significant limiting factor against the industrial application of irradiation.
Thus far, extensive research has been conducted into the removal of off-odor from foods and tap water. According to such research, absorbents such as active carbon, zeolites and diatomaceous earth, and functional oligosaccharides, such as cyclodextrin, have been found to remove smelly material. However, nowhere has research been conducted into the removal of off-odors from irradiated foods.
Leading to the present invention, intensive and thorough research into off-odor removal from irradiated foods, conducted by the present inventors, resulted in the finding that when packed along with irradiated foods, charcoal, known to remove various sources of smell, to emit far infrared radiation and anions, and to supply various minerals, can effectively eliminate off-odors from irradiated foods without influencing the tastes or physicochemical properties of the irradiated foods.
Therefore, it is an object of the present invention to provide a packaging method for removing off-odors from irradiated foods using charcoal.
In accordance with the present invention, the above object could be accomplished by the provision of a packaging method for removing off-odors from irradiated foods using charcoal, comprising:
The present invention pertains to the preservation of irradiated foods without the production of off-odors.
Hereinafter, the present invention is described in detail.
First, in the step (a), charcoal is packed into a sac and sealed.
Any charcoal made from various wood such as bamboo, pine trees, etc. in a typical manner may be used. For convenience, commercially available charcoal may be used. In a preferred embodiment of the present invention, powdered oak charcoal is utilized.
Any sac may be used to contain the charcoal powder as long as it neither leaks the charcoal powder nor has a bad influence on the function of charcoal. Preferably, a non-woven sac is employed. Non-woven textiles are those which are neither woven nor knit, but are manufactured without using threads. Non-woven fabric is defined as that manufactured by putting staples or filaments together in the form of a sheet or web and then binding them either mechanically (as in the case of felt), with an adhesive, or by interlocking them with serrated needles such that the inter-fiber friction results in a strong fabric. Whether it comprises felt or paper, non-woven fabric can be divided into 3 or 4 kinds. Non-woven fabric is suitable as a material for the charcoal sac because it is highly porous, not flexible, able to be sewn without unraveling, and fixable or thermally agglutinative.
Into the non-woven sac, charcoal is charged in an amount from about 1 to 15 wt % based on the weight of the food to be packed, and preferably in an amount from 5 to 10 wt %, followed by sealing the sac with the aid of a thermal sealer. If charcoal is contained in an amount less than the lower limit, it cannot effectively remove the off-odors from irradiated foods. On the other hand, if too much charcoal is used, it occupies too large a space in the package of the irradiated food and is economically disadvanageous. Into the sac, an absorbent or a preservative, such as zeolite or silica, in addition to charcoal may be further added.
Next, in the step (b), the sac including charcoal obtained in the step (a) is charged, along with foods, in a package, followed by sealing the package, either in a vacuum state or containing air.
The food package may be one known in the art to be suitable for packing foods. For instance, the food package used in the present invention may be made from multilayer polyethylene or laminated plastic films, but is not limited thereto. A typical gas or vacuum package method may be used.
Finally, in the step (c), the food in the package of the step (b) is exposed to radiation, along with the charcoal.
The irradiation is contained in high energy gamma rays, X-rays, and accelerated electron beams. A radiation source useful for food irradiation may be a radioactive nucleic species, such as Co-60 or Se-137, an up to 5 MeV X-ray generator, or an up to 10 MeV electron beam irradiator.
The irradiation is performed at a radiation dose from 1 to 100 kGy, preferably at a radiation dose from 1 to 20 kGy, and most preferably at a radiation dose from 5 to 10 kGy. A radiation dose less than 1 kGy cannot manifest an effect of irradiating the food. On the other hand, when irradiated at a dose higher than 100 kGy, the food may be not pleasant to eat.
The packaging method using charcoal in accordance with the present invention was assayed for off-odor removal in irradiated ground pork through various physicochemical experiments as well as a sensory test.
The ground pork which was irradiated along with charcoal in a package, was found to have substantially the same total bacterial count and E. coli count as a control which was irradiated alone in a package, so that there was no difference in microbiological properties therebetween (p>0.05) in addition, no significant difference was found in lipid oxidation and volatile basic nitrogen content between the ground pork packed according to the present invention and the control (p>0.05). These microbiological and physicochemical results indicate that the presence of charcoal does not influence the quality of the ground pork.
Contrastively, the packaging method using charcoal in accordance with the present invention was found to effectively remove off-odors from irradiated ground pork, measured through a sensory test and a difference test using an electronic nose. In the sensory difference test, the ground pork which was irradiated along with charcoal in a package was not significantly different from the ground pork which was not irradiated. However, an electronic nose testified that there was a significant difference in flavor between the irradiated ground pork stored along with charcoal in a package and the non-irradiated ground pork stored in a package and between the irradiated ground pork stored along with charcoal in a package and the irradiated ground pork stored alone in a package.
Solid-phase Microextraction (SPME)/gas chromatography-mass spectrometry (GC-MS) for volatile analysis detected aldehydes, alcohols, acids, ketones, benzenes, and various hydrocarbons from irradiated pork at considerable levels, but could only detect them at significantly reduced or non-detectable levels. Particularly, dimethyl disulfide, which is a main factor of the off-odors characteristic of irradiated meat, was detected from the pork irradiated at a dose of 5 kGy and 10 kGy, but from neither non-irradiated pork nor the irradiated pork packed along with charcoal.
Therefore, taken together, the experimental results imply that the presence of charcoal upon the irradiation and storage of foods effectively removes off-odors from the irradiated foods with no influence on the taste or physicochemical properties of the foods. The packaging method utilizing charcoal in accordance with the present invention can exert an excellent odor removal effect on all irradiated foods, that is, all meats, such as pork, beef, chicken, etc., fish, dairy products and so on. Further, the method of the present invention is expected to improve the safety and preservation of foods.
A better understanding of the present invention may be obtained through the following examples which are set forth to illustrate, but are not to be construed as the limit of the present invention.
1-1: Preparation of Non-Woven Sac Containing Charcoal Powder Therein
Charcoal used in this example was active carbon (Changwon, Korea) commercially available. Produced by further carbonizing a primarily heated charcoal at 1,000° C., the employed charcoal had a great number of expanded micropores and showed 3-5 fold higher absorbing power than typical charcoal. The powdered charcoal was prepared in an amount from 5 to 10 weight % of the pork sample into a small non-woven sac which was then sealed using a thermal sealer.
1-2: Irradiation
A piece of pork was put, along with the charcoal powder sac prepared in Example 1-1, in a general food package and sealed with air therein. The pork packaged along with charcoal in air was irradiated at room temperature (12±1° C.) at a dose of 83.3 Gy per min with gamma radiation (source 100 KCi, Co-60) in the Korea Atomic Energy Research Institute, so that the total absorbed dose of the pork amounted to zero, 5 r 10 kGy as measured by a ceric-cerous dosimeter, with the error allowance of total absorbed dose remaining within ±0.2 kGy.
After being irradiated, the pork packaged along with charcoal was used in the following various experiments. All experiments were performed twice. Statistical analyses were conducted with one-way analysis of variance (ANOVA) using SAS system Software (SAS Version 5 edition). In this regard, SNK (Student-Newman-Keuls) multiple comparison was conducted within 5% of the significance of mean values, and measured data were presented as mean values and standard deviations.
In order to determine the sensory quality of the pork which was irradiated along with charcoal in a package (hereinafter referred to as the charcoal-present irradiated pork group), off-odors were compared among the charcoal-present irradiated pork group, a charcoal-present non-irradiated pork group, a charcoal-absent irradiated pork group and a charcoal-absent non-irradiated pork group.
1-1: Difference Test
The effectiveness of removal of off-odors from the charcoal-present irradiated pork group prepared in Example 1 was examined through the following experiment.
Pork samples were tested for off-odor production using a ranking method in which each pork sample was ranked with regard to off-odors, and the sum of obtained scores and mean scores were calculated for statistical analysis. In this example, examiners were allowed to mark one for ‘no off-odor’ and six for ‘serious off-odor’ based on six levels of classification. Pork samples for the difference test were packaged along with 0, 5 or 10 wt % of charcoal and irradiated at a dose of 0, 5 or 10 kGy before testing.
The results are given in Table 1, below.
As is apparent from the data of Table 1, no off-odors were, detected from non-irradiated pork irrespective of the presence of charcoal, while the off-odors of the charcoal-absent irradiated pork were somewhat increased in a dose-dependent pattern. However, the charcoal-present irradiated pork was greatly reduced in off-odor irrespective of charcoal amount and radiation dose.
Thus, it is confirmed that the use of charcoal in the package of irradiated foods effectively removed off-odors.
Irradiation-induced lipid oxidation was measured using TBA (2-Thiobarbituric acid) methodology.
In order to measure TBA values of the pork samples treated as in Experimental Example 1, first, 0.5 g of each of the pork samples was homogenized, along with 50 μl of BHA (7.2% ethanol solution) and 16 ml of distilled water, in a 50 ml centrifuge tube with the aid of a homogenizer (DIAX 900, Heidolph, Co., Ltd., Germany). 1 ml of the homogenate was mixed with 2 ml of a TBA/TCA (trichloroacetic acid) solution (20 mM TBA in 15% TCA) and heated in a water bath for 15 min. After cooling, the resulting sample was centrifuged at 2000 rpm for 15 min using a centrifuge (UNION 5KR, Hanil Science Industrial Co., Ltd. Incheon, Korea). The supernatant was measured for absorbance at 532 nm (OD.532) using a spectrophotometer (UV 1600 PC, Shimaddzu, Tokyo, Japan). The concentration of malondialdehyde (mg/kg) was determined from a standard curve.
The results are summarized in Table 2, below.
As shown in Table 2, samples stored for two weeks were generally higher in absorbance than those stored for one week, which indicates that the lipid oxidation of pork increases as the storage period increases. In addition, irradiation was found to induce lipid oxidation in light of generally higher O.D. in irradiated pork than in non-irradiated pork. No significant change in absorbance was found even though charcoal was added, so that charcoal did not influence the lipid oxidation of pork.
Non-Irradiated Pork Using Electronic Nose
To examine the effect of the addition of charcoal on the off-odors of irradiated pork, the following odor test was performed using an electronic nose.
An electronic nose (FOX 3000, Alpha M.O.S., SA, Toulouse, France) equipped with an MOS (Metal oxide sensor) array and an automatic sampler was used in this experiment. 3 g of a pork sample and 0.3 g of charcoal were put in a 20 ml vial which was then sealed with a silicon/PTFE septum and an aluminum cap. Synthetic air (99.995% purity, 20% oxygen, and 80% nitrogen) was provided as a carrier gas at a rate of 150 ml/min. Relative humidity was adjusted using an air conditioner (ACU 500). The sample was incubated for 20 min at 50° C. in an incubator with agitation, after which gas was extracted from the headspace (2000 μl) of the sample using a gas syringe. Reaction data (ΔR/R0) of sensors were processed for Principal component analysis (PCA).
The results are depicted in
As seen in
To analyze the irradiated pork packaged along with charcoal for volatiles in the headspace thereof, the following experiment was conducted.
3 g of a pork sample and 0.3 g of charcoal were put in a 20 ml vial which was then sealed with a silicon/PTFE septum and an aluminum cap, followed by irradiation at 0, 5 or 10 kGy. A carboxene/polydimethylsiloxane (PDMS)-coated (75 μm thick) solid-phase microextraction (SPME) fiber (Supelco, Bellefonte, Pa., U.S.A.) was used to absorb headspace volatiles. Before the extraction of odor components; the analytes were desorbed at 250° C. for 5 min in an injection port of a gas chromatograph. Pork samples were maintained at 40° C. for 10 min in a heating block, followed by extracting headspace volatiles for 20 min with the SPME fiber. Next, the SPME fiber was injected into a gas chromatograph where the analytes were desorbed from the fiber. For the qualitative and quantitative analysis of headspace volatiles, a gas chromatograph (Varian Star 3400CX), a mass spectrometer (Varian Saturn 2000) and an HP-5 column (5% diphenyl and 95% dimethylpolysiloxane, 30 m×0.32 mm, membrane 0.25 μm thick) were used. Helium carrier gas was allowed to flow at a rate of 1 ml/min, with the injection port maintained at 250° C. After being maintained at 40° C. for 2 min, the temperature of the column was increased up to 250° C. at a rate of 3.5° C./min. Volatiles were identified using a mass analysis data base (NIST 98 or Saturn MS library).
The results are given in Table 3 and FIGS. 2 to 4.
**A˜Cthere is statistical significance between different letters in the same column.
As understood in Table 3 and FIGS. 2 to 4, irradiated pork samples produced more numerous and various volatiles than did non-irradiated pork samples. These volatiles were notably reduced or were not detected in the pork samples which were packaged along with charcoal before irradiation. Of the volatiles, particularly dimethyl disulfide, known as a main component to cause off-odors, was detected in irradiated pork samples, but not in the irradiated pork sample packaged along with charcoal.
Taken together, therefore, the data obtained implies that the packaging method using charcoal in accordance with the present invention can effectively remove the off-odors generated upon irradiation.
As described hereinbefore, the packaging method using charcoal in accordance with the present invention effectively removes off-odors from irradiated foods without influencing the sensory and physicochemical properties thereof, thereby allowing irradiation to be conducted and thus greatly contributing to food safety.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2005-0087592 | Sep 2005 | KR | national |
