Oxygen absorber is a relatively new technology for food preservation, which can increase the shelf life of different foods with proper packaging.
Oxygen absorber was invented in Japan and developed in other countries such as America, Australia and Taiwan, and recently in Iran, Baste Raz Salamat Paya company started producing this product under the brand name Bihava.
Oxygen absorber was invented in Japan and developed in other countries such as America, Australia and Taiwan, and recently in Iran, Mahdieh company started producing this product under the brand name Beyah.
We live in an era where we need to do our work as quickly as possible and save time as much as possible due to our busy schedule, so we turn to ready meals to meet our energy needs. .
Nowadays, the consumption of fast foods and prepared foods has increased a lot compared to the past, so maintaining the health and preservation of these foods has become very important.
In this article, we are going to discuss the preservation of one of the foods that is the basis of many fast food dishes: ham.
Ham (in French: jambon) is a food that is prepared from the thigh meat of animals such as beef or chicken and may be fresh or smoked and added salt and preservatives. Ham has more meat than sausage.
Introduction
The color of processed meat is a result of the compound nitrosyl hemochrome that is formed during the cooking process.
This chemical is sensitive to oxidation, which is intensified by light.
Also, oxygen can cause an unpleasant brown color in ham (Kinsman et al, 1994). Oxygen also leads to the spoilage of fats in meat, which results in the release of an unpleasant smell resulting from the rancidity of fats.
In addition, the presence of oxygen promotes the growth of aerobic organisms such as molds (which are among the main spoilage organisms in foods with low water activity). Processed meat products are usually either vacuum packed or the air inside their packaging is evacuated and carbon dioxide (CO2) or nitrogen gas is injected into it in order to prevent the spoilage of the ingredients in it. Also, packaging wrappers resistant to the passage of oxygen are used in order to limit its entry (what is meant by packaging wrapper is the same material that is known as cellophane or cellophane in the Iranian industry).
If we put the oxygen absorbers inside the ham packaging, they directly react with the oxygen located inside the packaging. When oxygen-resistant packaging wrappers are used in combination with oxygen absorbers, they can slow down the spoilage process of ham meat. One of the goals of this paper is to confirm and quantify these effects in a practical MAP packaging format.
The results of using oxygen absorbers
Oxygen absorbers combined with airtight packaging wrappers have been successfully shown to prevent spoilage and mold growth in foods such as cheese, cereals, and baked breads (Alarcon and Hotchkiss, 1993; (Smith et al., 1986).
Oxygen absorbers while preventing the oxidation of unsaturated fatty acids in fish; They solve the problem of color change in ham and eliminate this problem.
Allerton and Hotchkiss (1993) used wrappers with a very low oxygen permeability rate up to 32 cc/m2/24hrs along with vacuum packaging, and satisfactory results were obtained. In both levels of wrappers, oxygen absorbers played a very important role in removing and preventing the growth of fungi and molds in bread. In addition, it was observed that the adsorbents prevented the occurrence of unpleasant taste and odor in sunflower seeds and corn chips.
Andersen (1992) showed us that when oxygen absorbents are combined with airtight wrappers with an oxygen permeability rate of 2 cc/m2/24 hrs/atm, they can prevent discoloration (or discoloration) of pasteurized sliced hams. .
Comparison of oxygen absorber with other methods
The results obtained by using oxygen absorbers were of better quality than the conventional vacuum packaging method. Smith used plastic wrappers with the following specifications to investigate the control of oxygen concentration and fungal growth in packaged confectionery products:
40 cc@73 °F 1atm/m2 /24 hrs OTR
In this study, the adsorbent was able to reduce the oxygen in the empty space of the chamber to less than 0.05% during 9 hours and thus prevented the growth of fungus and mold in confectionery products for a period of more than 60 days.
In all three studies, very resistant wrappers were used against the passage of oxygen, and the oxygen permeability rate of OTR was very low for measurement, 2cc, 32cc, and 40 cc/m2/24 hrs/atm. Of course, to the extent that the properties of the packaging to prevent the passage of gases are greater, the cost for the supplier of meat products will be higher.
Of course, the injection of inert gases is another method of reducing the oxygen in the empty space inside the chamber, which is still an additional cost.
In general, if it is possible to increase the useful life and of course avoid the costs related to more resistant wrappers against the passage of gases by using commonly available wrappers, the results will be acceptable and more satisfactory.
Our main goal in this article is to investigate the effects of oxygen absorbers on the color, oxidation, microbiology, aroma and flavor of ham packaged in several different ways, under different light conditions and at different temperatures.
materials and methods
the product:
Majesty Inc. ham (Cranford, containing 1.8% fat and 17.9% protein) was used. The ham was kept at 4 degrees Celsius before being cut and packaged, and a total of 5 slices of ham, the thickness of which was about 3 mm, were randomly placed in 15 x 25 mm packages.
Materials used in packaging:
P640 (a packaging wrapper with relatively high blocking properties against the passage of gases) was used. This wrap was made of nylon/saran with an oxygen permeability rate of 60 cc/m2 and with the following specifications:
( OTR of 60 cc@73°F/1atm/m2 /24 hrs ( Cryovac,Duncan, SC
The oxygen absorbent packages were also manually placed inside the plastic wrappers, some of which were in contact with the product before the lid of the container was sewn.
Three types of oxygen absorbers, all with an oxygen absorption capacity of 10 cc, were used.
Packaging conditions
The 5 different types of packaging used in the experiment are depicted in Table 1 (the column of oxygen absorbers is related to the 3 types of oxygen absorbers used in the experiment, all three absorbers are 10 cc).
Test conditions:
After finishing the packaging, all packages were kept in the dark for 12 hours. This work was done in order to complete the effect of oxygen absorbers on the ham. All packages were stored in a cold room at 10 degrees Celsius with air circulation (proper ventilation) and with a relative humidity of 85% RH and exposed to continuous light.
The light sources in the storage room were fluorescent lamps (General Electric, F96T12) that were measured at 1076 lux at the product level.
Analysis and reviews
All examinations were performed under the same conditions on days 0, 9, 16, 23, 30, 37, 51, 65, and 79, and new packages were used during data collection.
The composition of the gas in the empty space inside the chamber
In the investigation of atmospheric compounds in the test, the concentration of oxygen and carbon dioxide gas was used by gas chromatography with the ability to detect and record heat transfer. In the stationary phase of the gas chromatograph, a molecular sieve column was used for oxygen gas and a chromosorb column was used for carbon dioxide gas. The mobile phase of the gas chromatograph was helium gas with a flow rate of 7.7 ml/min. The column temperature (stationary phase) was 65°C. The temperature of the injection syringe (injection system) was 100°C for oxygen gas and 120°C for carbon dioxide gas.
The detector temperature was fixed at 150°C. In this experiment, self-adhesive wall resin was used to seal each package. Airflow of the sample was performed using a 0.25 ml air-sealed syringe (Precision Sampling Corp., Baton Rouge, LA). The highest graphical point was analyzed using a stability table, with an accuracy of 0.5%.
Microbiological evaluation and review
The microbiological evaluation of the number of aerobic and anaerobic microorganisms and psychrotrophic bacteria and the counting of molds and yeasts was done by culture method in microbiological plates. The packages were opened under completely sterile conditions and 9 grams of the sample were mixed and homogenized with 99 ml of sterile phosphate buffer in a special sterile mixing bag called Stomacher Bag.
The contents of the bag were homogenized for two minutes in the Seward Stomacher 400 special bag homogenizer. 2 to 10 and 6 to 10 dilution solutions were prepared. Counting all aerobic and anaerobic microorganisms and psychrotrophs with the Plate Count Agar (PCA) method or the standard method of cultivation in agar medium and then keeping aerobic microorganisms at a temperature of 35°C for 48 hours and for anaerobic microorganisms at a temperature of 35°C for 5 day and for psychrotrophs at 7°C for 10 days.
Counting of molds and yeasts were plated with antibiotic agar culture medium and kept at 25°C for 5 days in a greenhouse. Finally, all results were reported based on the number of colony units formed in one gram (CFU/g) of food.
humidity
The moisture content of ham was determined by drying in an oven (AOAC method 950.46), in such a way that 10 grams of the sample was placed in a completely uniform mixer and 2 grams of it were placed in aluminum containers, and the samples were placed in a vacuum oven at 100 degrees Celsius for a period of time. They dried for 5 hours.
pH
5 grams of the sample was mixed well with 50 ml of distilled water and the resulting liquid was filtered using Whiteman paper filter.
Color measurement
The sample to be measured is selected from the upper part of the ham, which is covered with transparent plastic wrap inside the package, and by separating a section with a square cross-section, with the help of color detection detectors (L, a, and b) in the device Colorimeter (Macbeth Coloreye (Kollmorgan instruments Corp., Newburgh, NY) was measured.
Evaluation and measurement of fragrance
The available scent was measured and determined by a panel of 13 people, using a measurement scale from 1 to 15, which means no unpleasant smell to very unpleasant smell, respectively.
5 grams of the sample were placed inside a brown glass container with a screw door (it means a door that is closed and fixed with metal screws) on which labels with integers and digits from 0 to 9 were pasted.
Standards for fresh samples and strong odors are given as sources for the panels in each section in the References section.
Index TBA
In measuring the amount of thiobarbituric acid using the distillation method, in order to improve the product, it is the same method as explained by Koniecko (1979). In this method, 10 grams of the sample is mixed with 49 ml of deionized water (or distilled water) along with sulfanilamide reagent (at the ratio of 1 gram per 200 ml of 40% hydrochloric acid solution).
The obtained contents are thoroughly mixed with 48 ml of water in a closed bottle. Then the pH is adjusted to 1.5 using 2 ml of hydrochloric acid and the presence of anti-foaming agents along with glass pearl to reach the boiling point by heating it.
Statistical analysis and review
All the results of the experiments were analyzed using variance analysis and Fisher’s multiple comparison method on MINITAB computer software.
The results of investigating the increase in shelf life of ham using oxygen absorbers
All the variables of the packages were evaluated and reviewed until the end of the experiment (day 79). The amount of oxygen inside the packages on the first day was significantly different (<0.05) in different methods. In packages containing oxygen absorbers, the oxygen concentration in the inner space was lower and lower than those without absorbers. The difference in the initial oxygen concentration in the samples that were only vacuumed was greater than the samples that had gas injection.
From the ninth day of the experiment until the end, the oxygen concentration in all packages and in all test methods was about two percent. The reason can be that the oxygen in the closed interior space has been absorbed by microorganisms or the reaction of oxygen absorbers, related to the type of storage method.
The oxygen concentration that was expected to be observed in the method of zero percent oxygen absorbers (Anonymous, 1989) was not observed in this experiment, which may be due to the improper selection of the oxygen absorber compared to the oxygen in the packaging space or due to the leakage of oxygen gas from the packaging wrapper. .
The 8-day period between the two initial measurements, as well as the wrappers with low resistance to the passage of oxygen, lead to the entry of some oxygen, which ultimately helps to create a high oxygen concentration. Of course, it is possible that the 0.5% sensitivity of the gas chromatographic device itself causes the high oxygen concentration to be reported.
Finally, in the samples that were either vacuumed or packed with a combination of gases, the ham itself absorbs some of the atmospheric gases of the package. A delay in the growth and development of psychrotrophs, molds and yeasts along with color stabilization and the expected effects were observed at near-zero oxygen concentration, which will be discussed further.
Examining and interpreting the figures and graphs of the effect of oxygen absorber on ham
The effect of the presence of oxygen absorber on the growth of aerobic microorganisms
Figures 1 and 2 show the effect of the presence of oxygen absorber on the growth of aerobic microorganisms. The oxygen absorber had no effect on the growth process of aerobic microorganisms, either in vacuum or in the injection of sealed gas. The number of aerobic microorganisms did not increase suddenly until the end of the test, contrary to expectations. According to the findings of Anderson (1992), there was no significant difference in the number of aerobic microorganisms in vacuum packaging compared to the absence of oxygen absorber. Gas injection at a storage temperature of 10°C had no advantage over vacuum packaging in terms of microbial counts (Boerema 1993).
Figures 3 and 4 show the results of counting psychrotrophs in the ham sample. Oxygen absorber showed a significant (< 0.05) count of psychrotrophs during 9 days along with gas injection. But this difference became less from the 16th day onwards. However, in most cases, packages with adsorbent and gas injected with a low permeability wrapper had lower numbers of psychrotrophs than samples without adsorbent.
Microbial count results of molds and yeasts
Figures 5 and 6 show the results of microbial counts of molds and yeasts. Oxygen absorbers significantly delay the growth of yeast and molds in the presence of injected gases. The difference in the count of yeast and molds on days 9, 16, 23, 37, 51 and 65 in the presence or absence of oxygen absorber was significant.
The difference in the types of oxygen absorbers in the samples where no gas was injected was not significant. In the samples that were injected with gas, they had less microbial load than the samples that were only vacuumed. At a low concentration of carbon dioxide, it can have an inhibitory effect on the growth of mold, provided that the concentration of oxygen gas is significantly low (Smith, 1986).
Since no mold was observed during the test, it is possible that the oxygen concentration reached a critical level for mold and remained at this level throughout the test.
L detector value
In figures 7 and 8, with the help of L detector values, the light and dark color of ham samples are compared.
The values of the detector L in the ham in vacuum packaging without the presence of absorbent increased during the test, which indicates the increase in the whiteness and paleness of the ham sample. So that the color of the sample changes from pale pink to gray and the samples that had oxygen absorbers remained with the same pink color and a smaller increase in L indicator was observed.
A significant difference (>P 0.05) was observed between the samples that were vacuum packed on days 30 and 79. The same cases were observed for the samples that were packed by gas injection, so that if the oxygen absorbers were present in the packaging of the samples with an impermeable wrapper, they were very effective on the 30th, 37th, and 79th days of sample storage. Like other tests, the effect of oxygen absorber was not significant (> P 0.05). Oxygen absorber was effective in some tests, but it was not statistically significant.
Qualitative evaluations of other tests, such as the use of adsorbents, have no effect on the increase in anaerobic microbial load. In the first 23 days of the test, the number of anaerobes was rarely determined. The number of microorganisms after 23 days of the test had a big jump, from 10 to the power of 4 CFU/g on the 30th day to 10 to the power of 7 CFU/g on the 51st day. It was due to the lack of oxygen at the beginning of the storage life and the adaptation of microorganisms to these conditions.
During the test, the humidity remained stable at 74%. The initial variation was due to the difference in the moisture content of different cuts of the samples, which reached equilibrium after the first day. The initial pH of ham was 6.30 at the beginning and reached 6.00 at the end of the test.
TBA values, which determine the oxidation rate of fats, remained low with a small increase until the end of the test.
Conclusion :
Oxygen absorber in impermeable packaging delays the growth and development of psychrotrophic bacteria, yeast and molds and also leads to preservation of color in the ham sample, especially in packages filled with carbon dioxide gas. Oxygen absorbers in vacuum packaging can reduce the growth and development of psychrotrophic microorganisms and also reduce discoloration.
Oxygen absorbers in the wrapper with low permeability (compared to oxygen gas) do not prevent the color change of the meat product, but delay the undesirable color change that leads to the visual appeal of the product. In packaging with oxygen absorber, no significant change was observed in the amount of moisture, pH and TBA of ham.
Also, it was observed that less psychrotrophic bacteria grew in the packages that used oxygen absorbers than those that were packaged without absorbers.
As can be seen in the figures above, significant changes in the number of psychrotrophic bacteria can be seen between the packages with and without oxygen absorbers from the first day to the middle of the time period, but no significant difference can be seen from the middle of the experiment to the end. Finally, at the end of the experiment, it was observed that less psychrotrophic bacteria grew in packages with oxygen absorbers than those without absorbers.
Oxygen scavengers significantly retarded the growth of yeasts and fungi in fully depressurized packages.
The differences in the values observed on days 65 and 9, 16, 23, 37, 51 in the CO2 gas injected packages (between the two groups with and without absorbent) were significant.
References:
Alarcon, B. and Hotchkiss J.H. 1993. The Effect of FreshPax Oxygen-Absorbing Packets on the Shelf-Life of Foods. Technical Report, department of Food Science, Cornell University, Ithaca, NY.
Andersen H.J and Rasmussen M.A. 1992. Interactive packaging as protection against photodegradation of color of pasteurized sliced ham. International Journal of Food Science and Technology 27:1-8
Andersen H.J., Bertelsen, G., Boegh-Soerensen, L., Shek, C.K., Skibsted, L.H.. 1988. Effect of Light and Packaging Conditions on the Colour Stability of Sliced Ham. Meat Science. 22:283- 292.
Anonymous. 1989. New Oxygen Absorbing System Increases Shelf Life. Food Engineering 61:60.
AOAC. Moisture by Oven Drying. Official Methods of Analysis. Method 950.46.
Boerema, J.A., Penney, N., Cummings, T.L., Bell, R.G.. 1993. Carbon dioxide controlled atmosphere packaging of sliced ham. International Journal of Food Science and Technology. 28:435-442.
Kinsman, D.M., Kotula, A.W., Breidenstein, B.C.. 1994. Muscle foods : Meat, Poultry and Seafood Technology. New York : Chapman and Hall.
Koniecko, E.S. 1979. Handbook for Meat Chemists. Wayne, N.J : Avery Publishing Group.
Lawrie, R.A. 1991. Meat science. New York, U.S.A. : Pergamo Press.
Piggott, J.R. 1988. Sensory Analysis of Foods. London ; New York:Elsevier Applied Science, Elsevier Science Publishing Co.
Speck, M.L. 1984. Compendium of Methods for the Microbiological Examination of Foods. Washington, D.C.: American Public Health Association.
Smith J.P. et al. 1986. Novel Approach to Oxygen Control in Modified Atmosphere Packaging of Bakery Products. Food Microbiology 3:315-320.
Suzuki, H. et al. 1985. Effects of Oxygen Absorber and Temperature on Omega-3 polyunsaturated Fatty Acids on Sardine Oil During Storage. Journal of Food Science 50:358- 360.