EP2990340A2

EP2990340A2 - Method and device for packing individual products for horizontal-type packers

Info

Publication number: EP2990340A2
Application number: EP14788899.4A
Authority: EP
Inventors: Juan David RESTREPO MARTÍNEZ
Original assignee: Nacional De Chocolates Sas Cia
Current assignee: Nacional De Chocolates Sas Cia
Priority date: 2013-04-23
Filing date: 2014-04-23
Publication date: 2016-03-02
Also published as: WO2014174471A2; WO2014174471A9; WO2014174471A3; EP2990340A4; CO7100256A1

Abstract

The present invention discloses a method and a device for packaging individual products using horizontal flow packaging machines that possess an infeed conveyor that feed products individually into a packaging tunnel that seals the packaging lengthwise along the bottom using sealing media, and then seals the packaging transversally to form individual packages for each product, characterized by the injection of a gas stream into the packaging tunnel before the lengthwise sealing. The capillary device allows gas to be injected horizontally, that is, in the direction of the wrapping process.

Description

1. Field of the Invention

The present invention relates to a method and device for packaging individual products in horizontal flow packaging machines that inject an inert gas. The purpose of the present invention is to increase the shelf-life of products that degrade over time and suffer changes in their physical and sensory qualities, because of their organoleptic properties.

2. Abstract

The present invention discloses a method and a device for packaging individual products using horizontal flow packaging machines that possess an infeed conveyor that feed products individually into a packaging tunnel that seals the packaging lengthwise along the bottom using sealing media, and then seal the packaging transversally to form individual packages for each product, characterized by the injection of a gas stream into the packaging tunnel before the lengthwise sealing. The capillary device allows gas to be injected horizontally, that is, in the direction of the wrapping process.

3. Prior Art

Innovating and designing new technologies, and the environmental impact of organic and inorganic waste products, are some of the main concerns of the 21st century. Designing, developing and putting into operation a device that injects an inert gas, such as nitrogen (N₂), into products with solid ingredients, which are susceptible to oxidative rancidity, absorb humidity from their environment, and are also packaged using horizontal flow packaging machines, would allow the industry to increase shelf-life and increase the export destinations of these products.
In many cases, products that are about to expire are returned from the market to the companies, and the products and wrappings are shredded independently. In many cases, after grinding, the product is sold to industries that produce animal concentrate and the wrappers are taken to a landfill, where they cause sanitation and recycling problems, and among other things these waste products greatly impact the environment.
For example, EP0476834 discloses a horizontal flow food packaging machine that possesses a gas-injecting device which modifies the packages' internal atmosphere. The device is composed of an infeed conveyor, a plastic film feeder, a gas-injecting device, a roller system that seals lengthwise along the top of the product, and a transverse sealing system. This machine feeds the products into a chamber, in which the atmosphere contains the inert gas. This chamber allows multiple products to be fed in without an influx of air, in order to seal the packaging lengthwise and then seal it transversally. This prior art document indicates that the problem in modifying the internal atmosphere of the packaging lies in the slow packaging speed, since increasing the speed leads to issues with gas flow to ensure air influx and causes structural and vibrational problems that affect the machines' efficiency.
US4,272,944 discloses a product packaging system that packages continuously by removing air from the package by means of a tube inserted into the top of the line of products in order to create a vacuum throughout the lengthwise wrapping process. Just as most of the devices in prior art, in this document a vacuum is created at the top of the line of products, which causes problems when increasing the packaging speed and ensuring the withdrawal of air from the packaging.
US4,272,944 , US5,706,635 , US3,274,476 and EP07-61541 disclose gas injection or removal systems by laminar flow in a packaging process using horizontal flow packaging machines. US4,272,944 and US5,706,635 disclose gas removal and indicate that there must be a chamber from which air is constantly being extracted. US patent 3,274,746 discloses a horizontal flow packaging machine that creates a vacuum using the same principle of employing a tube with an orifice to eliminate air from the packaging when the lengthwise sealing process begins.
EP07-61541 discloses injection of a gas, in which a tunnel through which products pass is injected with a gas. This document claims gas injection at any part of the tunnel at low speed, preferably at the tunnel's inlet as well as at its outlet, thereby reducing the oxygen-containing air that can flow into the tunnel and keeping the inert gas inside the tunnel at a higher concentration and purity. Just as the previous documents, this one involves horizontal flow packaging machines that seal lengthwise at the top of the product.
Although the prior art is filled with disclosures of devices that remove air from packaging, it claims the injection or removal of a gas within a horizontal packaging process in which the lengthwise sealing of the products is done at the top part of the wrappers. An important problem in these cases is the high variability of removing or injecting as much gas as possible from/into the packaging. Another main problem with these devices is the slow packaging speed, due to the very structure of these devices, as it is difficult to establish a packaging rhythm when removing or adding a specific quantity of air from/to the product packaging.
There are drawbacks to using machines that seal lengthwise at the top of the packaging: i) when the product is entering the lengthwise sealing area, the product creates a space at the top of the packaging where it is sealed, such that unwanted gas might remain, or the packaging speed might have to be reduced to ensure that these gas pockets inside the product seal do not form; and ii) this method of sealing at the top of the product means that the tube that removes or injects inert gas must be present all along the lengthwise sealing portion of the packaging, which makes the process inefficient. A person skilled in the art would understand that when a tube with flute-like holes is used, the end closest to the gas flow will receive a greater flow of gas, and thus, the end farthest from the gas flow will receive a diminished flow.
Because of the above, there is an interest in developing a device that allows for inert gas injection in a horizontal packaging process, in order to increase product shelf-life by preventing oxidative rancidity and mitigating the effects of environmental conditions at the storage and/or display site.

4. Figure Descriptions

Figure 1 shows a horizontal flow packaging machine.
Figure 2 shows the packaging material when the rollers are sealing the product lengthwise.
Figure 3 shows lengthwise and transverse packaging of products in the packaging machine.
Figure 4 shows the wrapping unit for products A and B, and the wrapping process.
Figure 5 shows embodiment A of the capillary tube.
Figure 6 shows embodiment B of the capillary tube.
Figure 7 shows a view of embodiment C of the capillary tube.
Figure 8 shows another view of embodiment A of the capillary tube.
Figure 9 shows the holes in the unit that hold and guide the capillary tube.
Figure 10 shows the "C" capillary adding nitrogen (N₂) to the product wrappings A and B.
Figure 11 shows the underside of the injection system.
Figure 12 shows the packaging material in the packaging machine.
Figure 13 shows the result of putting the capillary tube into operation: residual oxygen percentage (O₂) in product A.
Figure 14 shows a pilot test: Residual oxygen (O₂) percentage (%) in product A.
Figure 15 shows a final test: Residual oxygen (O₂) percentage (%).
Figure 16 shows results for product A: residual oxygen (O₂) percentage and olfactory sensory analysis.
Figure 17 shows results for product A: residual oxygen (O₂) percentage and color sensory analysis.
Figure 18 shows results for product A: residual oxygen (O₂) percentage and texture sensory analysis.
Figure 19 shows results for product A: residual oxygen (O₂) percentage and taste sensory analysis.
Figure 20 shows results for product B: residual oxygen (O₂) percentage and texture sensory analysis.
Figure 21 shows results for product B: residual oxygen (O₂) percentage and taste sensory analysis.
Figure 22 shows results for product B: residual oxygen (O₂) percentage and olfactory sensory analysis.
Figure 23 shows results for product B: residual oxygen (O₂) percentage and color sensory analysis.

5. Brief description of the invention

The present invention discloses a method and a device for packaging individual products using horizontal flow packaging machines that possess an infeed conveyor that feed products individually into a packaging tunnel that seals the packaging lengthwise along the bottom using sealing media, and then seals the packaging transversally to form individual packages for each product, characterized by the injection of a gas stream into the packaging tunnel before the lengthwise sealing. The capillary device allows gas to be injected horizontally, that is, in the direction of the wrapping process. This capillary tube is designed with a pointed end so that it provides good direct flow, causing the entire wrapping tunnel to be filled with inert gas as it forms and displacing the greatest possible amount of oxygen (O₂) in order to preserve the product.
The total space where the capillary tube is installed measures 3.15 mm. The top part of the tip is flat and rests at the level of the conveyor (the part of the machine that moves the products along to be wrapped) so that the product is not lifted up, since that would cause an obstruction in the packaging machine.

6. Detailed description of the invention

The present invention discloses a method and a device for packaging products in horizontal flow packaging machines, by means of a capillary tube-like device that directs the flow of an inert gas that displaces the greatest possible amount of oxygen (O₂) inside the packaging, in order to preserve the product.
Referencing Figure 1, we describe a horizontal flow packaging machine that is composed of a roller (1) that holds the wrapping paper roll (2), threaders (3) to pass the material in a zig-zag pattern in order to tighten it and feed it to the wrapping unit (4) correctly. The machine has a conveyor (5) that is rotated by a chain and functions to transport individual unwrapped products (12) to be wrapped. Before this step, the product is wrapped with wrapping paper by a pair of pinch rollers (6) and then by two pairs of lengthwise sealing rollers (7), and is then passed on to the transverse sealer (8), resulting in an individually wrapped product (9). Both seals are made using heat.
The capillary tube (13), which will be described in detail in Figure &, is an element located at the point labeled (10). This capillary tube is able to displace the greatest possible amount of oxygen (O₂) from inside the packaging while the it is being sealed lengthwise and transversally.
In experiments conducted in order to design the capillary tube, the number of product units in the packaging machine in Figure 1 was taken into account when the products are being wrapped (from the pinch rollers (6) to the transverse sealer (8)). In order to achieve this, the amount of gaseous fluid that must be continuously present during the wrapping process must be known, since the process is carried out continuously.
Figures 2 and 3 show the area where the pinch rollers (6) are located. To calculate the amount of gas that the device needs to provide, paper is taken from the roll (2) shown in Figure 1; it must be a heat-sealable paper with high barrier protection. In preferred embodiments, it can be polyester and metalized propylene paper that keeps external elements from entering the product, and at the same time also retains the nitrogen (N₂). The paper is installed in the packaging machine (Figure 1) by passing its end through the threaders (3), and then passes through the wrapping unit, which shapes the packaging to receive the line of products that are wrapped by the packaging. At the point where the two ends of the packaging meet, the pinch rollers (6) pull the ends of the packaging toward the lengthwise sealing rollers (7), which thermally seal the packaging lengthwise and lastly toward the transverse sealer (8), where the packaging is sealed transversally.
It is worth noting that the measurement performed in this experiment is intended to show with certainty the number of products present in the packaging machine, in order to determine where the inert gas should be added (10). In preferred embodiments of the invention, the inert has is selected from gases such as nitrogen (N₂). After determining the point where the inert gas must begin to be added (6), the lengthwise sealing (7) is performed, followed by the transverse sealing (8), which will be explained in detail further on.
Figures 2 and 3 show perspective views of the lengthwise sealing process, in which the sample embodiment showing three and a half unwrapped units (12) can be seen. In the described embodiment, the calculations of the amount of gaseous fluid versus the number of product units that must be in the packaging machine were performed for four unwrapped product units (12).

Volumetric analysis:

To determine the flow rate of the gaseous fluid that must be injected into the tunnel formed in the packaging machine (Figure 4, right side), the number of inert gas (e.g. nitrogen (N₂)) replacements that must be injected to ensure that the greatest amount of air is removed from the wrapping paper tunnel (14) formed by the packaging machine must be calculated. This shows how much gas must be flowing when the gaseous fluid is injected into the horizontal flow packaging machine (Figure 1). The result of the calculation is a theoretical value that serves as a baseline to begin nitrogen (N₂) addition.
After measuring the number of product units in the packaging machine (Figure 2), the wrapping paper tunnel (14) containing four units was taken to the physicochemical lab to conduct a volumetric test, which yielded a volume of 300 cm³. Then, four units weighing 23 grams each were added and pressure was applied to push them to the bottom of the graduated cylinder to see how much water (H₂O) they displaced, yielding a volume of 420 cm³. By finding the difference between these volumes, the volume of nitrogen (N₂) that the wrapping paper tunnel (14) must contain is obtained.

Theoretical flow rate calculation

In this stage, the theoretical flow rate for the nitrogen (N₂) injection process is calculated, in order to find a value that can be used to carry out the first test of the capillary tube injecting the gaseous fluid, considering that since the process is continuous, it is necessary to know the flow rate required to remove the greatest amount of oxygen (O₂) from the inside of the wrapping paper tunnel (14). See Figure 2.
To obtain this value, it is necessary to start with a formula (Equation 1) that was created and is used by a company that supplies medicinal and industrial gases. Equation 1 contains a numeric term, called the theoretical replacement factor, is a standard value given by the same medicinal and industrial gas supplier company, and it denotes the flow replacement necessary to remove the oxygen (O₂) from the air inside the packaging.
Having obtained this information (see Table 1) the theoretical gaseous fluid flow rate is calculated: Table 1

Theoretical Flow Rate Data

Volumetric Capacity (cm³)

Machine Speed (Units/min) 420

Theoretical Replacement Factor 3

$Q_{theoretica l} = (Volumetric Capacity) * (replacemen t factor) * (Machine Speed)$
Substitution with the mean values: $Q_{theoretica l} = (120 {cm}^{3}) * (3) * (420 units / \min) * (\frac{60 \min}{1 hour}) * (\frac{1 m^{3}}{100^{3} {cm}^{3}})$
$Q_{theoretical} = 9.07 \frac{m^{3}}{hour}$
The reference theoretical flow rate is 9.07 m³/hour. This flow rate results in a reading of 180.5 SCFH (standard cubic feet per hour) on the flowmeter. In the embodiment described in the present invention, in which four product wrappers are used, the capillary tube is put into operation with this flow rate, which is corroborated by the ideal output pressure of the gaseous fluid using a pressure regulator for gases, taking into account that these two variables (flow rate and pressure) remove as much oxygen (O₂) as possible from the inside of the packaging.

Method for packaging individual products of the present invention

The design of the device that injects a gaseous fluid into the wrapping paper tunnel (14) (Figure 4) and displaces any oxygen (O₂) present was based on observation of the product wrapping process, where before the process begins, the product passes through a conveyor (5) (see Figure 1), thereby forming a line of unwrapped products (12). In this process, the wrapping paper (2) passes through the threaders (3) (see Figure 1), then the wrapping paper arrives at the wrapping unit (4) that has a slots (15) through which the paper enters to begin forming the wrapping tunnel (14) (see Figure 4). Later, the verify how the first lengthwise sealing (7) (Figure 1), in which the wrapping paper tunnel (14) is sealed, is performed (see Figure 3), and lastly check how the second transverse sealing (8), after which the products are individually wrapped (9), is performed (see Figure 1). As an example, the line of products in one of the embodiments can be composed of products A or B, which are twenty-three gram bars that contain perishable ingredients.

Device for adding the gaseous fluid

The device of the present invention injects gaseous fluid through a thin capillary tube, and placed at the level of the wrapping unit so that the product does is not lifted up, since that could cause an obstruction in the machine, as stated in the prior art.
The capillary tube (13) of the present invention (see Figure 7) ensures that enough flow to feed the wrapping paper tunnel (14) is supplied, and also ensures an adequate gas pressure, so that inert gas is not oversupplied, as this would cause a high gaseous fluid consumption, and so that the product is not lifted, as that would cause an obstruction in the machine. This is precisely what the prior art has not been able to achieve when it claims to use flute-like tubes to extract or inject a gaseous fluid. The injector of the present invention is located where the product wrapping begins (11) (see Figure 1), because otherwise, the productivity of the packaging process would be reduced.
The present invention suggests multiple embodiments of devices that allow for inert gaseous fluid addition to remove the oxygen (O₂) from food product packaging. Each embodiment was subjected to a viability analysis, taking into account the variables involved in the process, such as flow rate, the injection pressure of the gas, and the roller temperature needed to create the seal.

INJECTOR EMBODIMENT A

Figure 5 shows embodiment A, which is a capillary tube (1) with five holes (16) spaced out so that the gaseous fluid flows when the wrapping paper tunnel (14) (Figure 4) begins to form with the product.
In the process of designing the holes of the capillary tube, a prediction based on flow dynamics concluded that most of the gaseous fluid would exit vertically from the first two holes, and would add gas to the product but not around it to displace any oxygen (O₂) preset. This results in inefficient gas addition because it does not ensure adequate oxygen (O₂) displacement. The pressure and speed of the fluid would be greater through the first two holes, causing the product to be lifted up and obstruct the packaging machine. This is the most common device in the prior art, and does not provide an adequate solution for injecting or removing gas into/from the packaging.
This embodiment does properly direct the gaseous fluid and does not yield good results, since the gas escapes the wrapping paper tunnel. Furthermore, the mount (17) (Figure 5) that was designed does not fit into the packaging machine, so there is no way to firmly secure it so that it does not fall during the wrapping process and there is no way to feed the wrapping paper (2) (Figure) through unit B (Figure 4).

INJECTOR EMBODIMENT B

Embodiment B us a capillary tube (1) that is composed of five separated, elongated tubes (18) with circular outlets (Figure 6). The principle for adding the gaseous fluid to achieve a modified atmosphere is to add the inert gas through the bars vertically before beginning formation of the wrapping paper tunnel with the product.
Embodiment B consists of tubes (18) that protrude from the capillary tube (1). Their circular outlet would be almost flush with the conveyor (5) on which the products pass. The issues caused by this design are: the gas would flow out vertically and would take too long because of the tubes (18) that protrude from the capillary tube (1), and amount of inert gas that flows out would not be enough to increase the shelf-life of the product, because it would not remove enough oxygen (O₂) from the wrapping paper tunnel (14) (Figure 14). Similarly, the cylinders (6,7) would not be level with the conveyor (5) on which products A and B pass, making the machine to come to a stop.
Lastly, the same problem as the previously described design, which is that the mount (17) (Figure 6) for the capillary tube would not be stable when the gas is injected and would shake, causing problems in the lengthwise and transverse sealings and would not allow the wrapping paper to pass through unit B (Figure 4). Furthermore, the gas would flow out of the first two elongated tubes, in the same way as the previously described capillary tube.

INJECTOR EMBODIMENT C

The third embodiment of the capillary tube (13) (Figure 7) uses a design principle that involves adding the gas horizontally, that is, in the direction of the wrapping process. This design has a pointed end that can supply a direct flow that is able to displace the greatest possible amount of oxygen (O₂) in order to preserve the product.
This embodiment is a capillary tube (13) that allows for the efficient injection of inert gas into the packaging, since this device shape and configuration does not cause any turbulence, but quite the opposite, provides laminar injection of the inert gas in the wrapping paper tunnel (14). The capillary tube (13) consists of an oval tube with a hole in the center with a pointed triangular tip (19) (Figure 7), that properly directs the flow so that the whole wrapping paper tunnel (14) (Figure 2) is filled with nitrogen (N₂) when it is forming. The top part of the tip is flat and has a hole that lets out gaseous fluid (24) (Figure 7) and is level with the conveyor on which nut-containing products pass. The capillary mount (17) can be fitted to unit B (Figure 4) of the packaging machine (Figure 1), and as was mentioned above, there is not much space available to install it.
The capillary tube (1) is S-shaped and has a fast coupling (25) (see Figure 7), which allows it to connect to hoses with an external diameter ranging from 6 mm to 10 mm. This plastic hose is placed below the packaging machine (Figure 1) and transports the gaseous fluid without the need for a special mount. In the preferred embodiment, the dimensions of the oval-shaped hole in the capillary tube are 1.5 mm internal diameter and 3 mm external diameter, and the intake hole is 20 mm wide. In the preferred embodiment of the present invention, the capillary tube is made from 304 stainless steel.
Figure 8 shows a frontal and top view of the capillary tube (1) (Figure 7), the two holes (24) through which gaseous fluid flows out, the mount (17) and the fast coupling fitting for a hose (25). The capillary tube mount (17) consists of a hole with a screw that holds the capillary tube (26) and next to it, a guide point (27) to enable placement inside product unit B (Figure 4), which serves as a guiding point to signal that the capillary tube (13) (Figure 7) is properly oriented.

Mounting

Before starting to mount the capillary tube (17) (Figure 7), two small holes (28) and (29), which can be seen in Figure 9, were drilled into the unit for product B (Figure 4). One of them holds the capillary tube (29) in conjunction with the screw (21) and the other one (28) is for aligning the guide point (27) so that the same orientation is preserved during installation.
Figure 10 shows two (2) important features. The first is that the capillary is shown properly installed and placed in the wrapping unit for products A and B so as to avoid problems during the wrapping process. The second is that it shows how nitrogen (N₂) would flow out of the two holes of the capillary tube.
The tip (1) must be centered for the following reasons:

1. So that the inferior portion of the injection system is kept to one side of the pinch rollers (8), since these rotate and could cause friction with the capillary tube (13). The pinch rollers (8) are moved by a chain in the packaging machine (see Figure 11). Their function is to move the products along to be wrapped.
2. So that the wrapping paper (2) is off to the sides of the capillary tube (13), so as to keep the gaseous fluid from escaping out from the sides and so that it flows properly and produces a proper lengthwise seal. See Figure 12.

In order to properly place the capillary tube (13) (Figure 7), the screw (21) and the guide point (27) (Figure 8) must be placed in the product unit (4) (Figure 9), ensuring that they are screwed in properly. These two reference points are located at the top of the mount (17) (Figure 8), and once the above instructions are completed properly, inert gas injection can begin.

Start-up

The initial start-up of the capillary tube (13) (Figure 7) is carried out to observe whether inert gas flows out and how the newly installed device performs with the wrapping unit of the machine, the wrapping material and, in general, with every part of the machine that is involved in the wrapping process. In preferred embodiments of the invention, the speed of the packaging machine is 420 units, minute.
As was previously stated, the variables used were theoretical (pressure in the regulator and flow rate in the flowmeter), because this is a new process in horizontal flow packaging machines. Thus, the parameters needed to begin the inert gas injection process are theoretical.
The resulting residual oxygen (O₂) percentage was not satisfactory, because an average of only 3% of the oxygen (O₂), from the 21% contained in air, was removed from each product unit. Thus, the theoretical data do not apply to the process, because the amount of inert gas will quickly be lost when the product enters the climatic chamber.
Since unsatisfactory results were obtained using the theoretical data, the regulator valve was changed from 20 psig to 45 psig in order to determine the proper output pressure of the inert gas. See Table 2.
Table 2 shows the residual oxygen (O₂) percentage results for the ten product units analyzed and their respective working pressure, in which we found that the products had an increased shelf-life; taking into consideration the fact that only products with a minimal amount of residual oxygen (O₂) can be brought to the international market.
According to Figure 13, the proper working pressure is 30 psig (2.0414 atm), because this pressure produced the best residual oxygen (O₂) percentage (%) results. Five (5) product units had the lowest amount of oxygen (O₂), with a residual oxygen (O₂) percentage of 8%. It is worth mentioning that the packaging process in continuous, which is why the packaging speed is high and leads to some variability in values from different samples.
The other five product samples did not yield the same results, but their difference is so minimal that they are considered to be within the acceptable range.

PILOT TEST

This pilot test involved a 23-gram product A and slowing down the speed of the packaging machine (Figure 1) to 380 units/minute without affecting the productivity of the overall process. The machine's speed was reduced in order to allow for a longer injection time, and so that the product wrapping process is carried out more slowly. This means the inert gas, nitrogen (N₂) in this case, can better sweep the oxygen (O₂) away, thereby continuously enclosing the greatest possible amount of inert gas in the tunnel in formation.
If the packaging machine continues to slow down, the driving conveyor (1) (a machine that comes before the packaging machine (Figure 1), it moves the products to the conveyor (5) (Figure 1), which then transports the products to be wrapped) starts to fill up with products, thus affecting the productivity of the process, since it causes less units to be wrapped per minute. Another reason why this affects the productivity of the process is that the product remains on the driving conveyor, because it is not wrapped during the current work shift.
The driving conveyor (1) transports the products so that the operator can collect them in trays at the end of the line and store them to be wrapped during the next work shift, leading to delays in the production process of the other products processed by this line.

Beginning of the wrapping process

The machine is allowed to stabilize for five minutes so that it reaches the preset packaging speed. Once the machine is stable, the first ten consecutive samples that the machine produces are taken. Their hermetic seal and then their residual oxygen (O₂) percentage (%) are measured.

Nitrogen (N₂) addition

This process is performed by increasing the pressure in 5 psig increments, up to 45 psig (Table 3), and the hermetic seal and residual oxygen (O₂) percentage are measured for each working pressure used in the process.
Figure 14 corroborates the observations of the capillary start-up: that the gas output pressure that best sweeps oxygen (O₂) away is 30 psig (2.0414 atm), because six units yielded a residual oxygen (O₂) percentage of 7.6%. One sample yielded 7.7% and another yielded 7.8%, both of which are close to the 7.6% value. The first and second samples yielded 9.7% and 9.1% respectively, which are not close to the aforementioned samples, but are acceptable for the nitrogen (N₂) injection process.

Methods of the experimental procedure: pilot test - industrial

The process began on week zero (the day the products were wrapped) by selecting five samples each of products A and B. These were taken to the physicochemical lab in order to measure their residual oxygen (O₂) percentage and perform physicochemical analyses (percent (%) humidity in an oven and water activity), sensory analyses and a microbiological analysis.

Climatic chamber

Sixty bar units of products A and B with and without nitrogen (N₂), that is, a total of two hundred and forty units, were taken to the climatic chamber to carry out a simulation of product preservation by accelerating temperature and humidity conditions to see how it would perform in the market. The chamber was programmed to 30°C with +/- 2°C variation and 75% relative humidity (RH) with +/- 2% RH variation.
For these analyses, the products were kept in the climatic chamber for twelve weeks. Five units of each product with and without nitrogen (N₂) were removed (a total of twenty removed from the climatic chamber) each week.

Sensory analysis

This analysis was carried out to assess the state of the product using the senses: smell, taste, touch and sight. Only very well developed senses can give objective, and not subjective, results. This is achieved by means of tasters that undergo intensive training to be able to distinguish each product.
The people that make up a sensory panel are the primary tools used in this analysis, since humans are sensitive, as opposed to machines, which cannot provide the results needed to perform an effective assessment.
The methods of this analysis were the following:

Every week, each member of the four-person panel was given products A and B from the climatic chamber (the aforementioned five samples of each product with and without nitrogen (N₂) that were removed from the chamber). Of these five samples, one was used for physicochemical analyses, one was used for microbiological analyses, and the remaining three were given to the members of the sensory panel.

The members of the sensory panel know how the products are formulated and produced in detail. Each member opens the product and analyzes each feature (smell, texture, taste, appearance, color).
After these five features are analyzed, each member of the sensory panel rates each of these from one to five. Table 4 shows each sensory rating and its respective description. Table 4

Sensory Rating Description

1 Very bad

2 Bad

3 Average

4 Above average

5 Good

MICROBIOLOGICAL ANALYSIS

Mesophilic aerobe count

The goal is to establish the method to determine the amount of microorganisms that grow on a solid medium after aerobic incubation at 35°C +/- 2°C for 48 hours.

Mold and yeast count

The method describes how to count the molds and yeasts present in a product by counting the colonies that grow on a solid medium after aerobic incubation at 22°C +/-2°C (room temperature) for 5 days.

Total and fecal coliform count

This method allows for determination of the presence of total and fecal coliforms in a sample by means of a liquid culture specific to each of these groups of microorganisms.

Industrial test

Before beginning the test, the lengthwise sealing rollers and the transverse sealing clamps were cleaned in order to obtain a better seal, so that the added nitrogen (N₂) does not escape from the packaging too quickly and in turn, ensure the harmlessness of the products. Product B was used in the industrial test.
In this test, the time elapsed from nitrogen (N2) injection, when lengthwise sealing begins, until the transverse sealing was calculated.
The data needed to calculate the time are the following:

✔ Length of each product unit: 140 mm
✔ Machine packaging time: 380 units/minute
✔ Total units, from nitrogen (N₂) injection until transverse sealing: (3 ½) units, with a total length of 490 mm.

Using the data with consistent units, the time was calculated using Equation 2: $Distance = Speed * Time$

Time = 0.5526 seconds
Table 5 shows the residual oxygen (O₂) percentage results.
Figure 15 shows the residual oxygen (O₂) percentage (%) of the ten analyzed samples. In this final test, six (6) samples yielded a residual oxygen (O₂) percentage of 6.7% and four (4) samples were between 7.0% and 7.4%. This means the samples are still acceptable.
The residual percentages (%) are lower than in previous test. This was due to the cleaning of the sealing units, as was stated above, but this is not a decisive factor in the nitrogen (N₂) addition process, since the values are still close to those of the samples analyzed in previous tests, which were wrapped with the same inert gas output pressure.

Actual calculations of the nitrogen (N₂) addition process

FLOW RATE THROUGH THE CAPILLARY TUBE

To calculate the flow rate through the triangle-tipped capillary tube, which enters the wrapping-material forming tunnel, Equation 3 (taken from Perry's Handbook) was used as follows: $Q_{real} = Q_{0} * \frac{T_{2}}{P_{2}} * \sqrt{\frac{P_{0} * P_{1} * M_{0}}{T_{0} * T_{1} * M}}$
Where:

To [K] = Air temperature of the work environment.
P₁ [KPa]= Nitrogen (N₂) output pressure.
Q₀ [m³/h] = Flow rate reading from the flowmeter.
T₂ [K] = Temperature in the work environment; equal to T₁.
P₂ [KPa] = Working pressure.
P₀ [KPa] = Air pressure.
Mo [g/mol] = Molecular of air.
M [g/mol] = Molecular weight of nitrogen (N₂).

As stated previously, the flowmeter reading was 30 SCFH (30 ft³/h), which is equivalent to 0.85 m³/h.
The molecular weight of air is 28.98 g/mol and the molecular weight of nitrogen (N₂) is 28.01 g/mol.
The actual flow rate was then calculated with Equation 3 using the data. $Q_{real} = 0.85 * \frac{21.00}{101.43} * \sqrt{\frac{101.43 * 308.43 * 28.98}{21.00 * 21.00 * 28.01}}$
$Q_{real} = 1.51 \frac{m^{3}}{h}$

REYNOLDS NUMBER

The Reynolds number is defined as the flow pattern inside a tube; it is laminar if the Reynolds number is less than or equal to 2000 and it is turbulent if the Reynolds number is greater than 2000.
The theoretical Reynolds number is calculated below, using Equation 4, which was taken from the 3rd Edition of Mechanics of Fluids by Merle Potter. $R_{e} = \frac{4 * Q_{real}}{π * D * ϑ}$
Where:

R_e= Reynolds number
Q [m³/s] = Flow rate of nitrogen (N₂).
D [m] = Interior diameter of the capillary tube.
ϑ [m²/s] = Kinematic viscosity of the gas.

The following is used to calculate the flow pattern: Q_real= 1.51 m³/h (4.19x10^-4 m³/s), internal diameter of the capillary tube = 1.5 mm (1.5x10^-3 m). To calculate the kinematic viscosity of nitrogen (N₂), the working temperature (21°C) and the pressure (0.85 atm (640 mmHg)) were entered into the Hysys simulation program, which yielded a kinematic viscosity of 15.62 cSt (1.56x10^-5 m²/s) under these conditions. The Reynolds number was then calculated with Equation 4 using the data. $R_{e} = \frac{4 * 4.19 \times 10^{- 4}}{π * 1.5 \times 10^{- 3} * 1.56 \times 10^{- 5}}$
$R_{e} = 2.28 \times 10^{4}$
The numeric value of the case we have been examining, given by the previous calculation, is 2.28x10⁴. The theory states that the flow pattern is turbulent for Reynolds numbers greater than 4000 (4x10³).

Analysis of the pilot test results - industrial

The results of the physicochemical and microbiological pilot and industrial tests fall within the quality standards, therefore meaning that the product is suitable for human consumption.

Residual oxygen (02) percentage (%) and sensory analysis - pilot test

There are very important variables that determine the quality of a product that cannot be measured by laboratory equipment. These variables are subjective, but the company employs a group of highly trained individuals for their analysis (Sensory Panel), whose senses are developed enough to detect variations in texture, color, flavor, appearance and smell. Table 6 shows the interpretation of the sensory results.
Tables 6 and 7 show the residual oxygen (O₂) percentage (%) results and the sensory results over time for the product with and without nitrogen (N₂) for products A and B, respectively.
Although Tables 6 and 7 show that the week-to-week residual percentage is the average of the analyzed samples, upon closer inspection of the W.N. and W/O.N. columns, these values increase or decrease after the product was subjected to accelerated humidity and temperature conditions in the climatic chamber.
There are two reasons why the residual oxygen (O₂) might increase: 1) the nitrogen (N₂) may escape through the wrapping material, even though the wrapper has a high protection barrier, and 2) there may have been micro-leaks at the moment the product was sealed. If it is caused by one or both of these reasons, the inert gas would escape from the product, allowing oxygen (O₂) to flow in, which is why a high residual oxygen (O₂) value can be obtained when it is measured.
The sensory results of the pilot test show that the appearance variable of the product did not change, whether it contained nitrogen (N₂) or not, over the twelve weeks it remained in the climatic chamber. Figures 16 and 17 show that he product without nitrogen (N₂) began to change in week nine, in which the smell and color ratings dropped from five to four for the remaining weeks of the test.
The texture and taste ratings also began to change in the same week, but beginning in week ten, they continued to drop from four to three until week twelve. This change is evidenced in Figures 18 and 19.
The W.N. columns for texture, smell, taste and color show a rating of four in week twelve. This is due to the state of one of the raw materials that has a high water content, which changed the product's nutritional properties and shortened its shelf-life. Bear in mind that this product does not turn rancid.
In previous studies conducted by the company on the shelf-life of product A, it was found to last eight months on the market. That is confirmed by this study, as evidenced by the Figures shown above. The lines for the sensory variables that correspond to product A without nitrogen (N₂) show that sensory changes begin to occur after week eight, which did not happen to product A with nitrogen (N₂), which lasted three more months. This means the product will have a shelf-life of eleven months on the market.

Residual oxygen (02) percentage (%) and sensory analysis - industrial test

Five samples with and without nitrogen (N₂), for a total of ten units, were removed from the climatic chamber each week for residual oxygen (O₂) percentage (%) measurement, except for when the analysis began, in week zero (the day the product was produced).The residual oxygen (O₂) of each sample was measured, after which their average was calculated. This is the datum reported in Table 7.
The members of the sensory panel were given three samples with and without nitrogen (N₂), for a total of six out of the ten samples available each week. Each member of the sensory panel judged the product and gave his/her rating of the five sensory features for all twelve weeks. The results are reported in Table 7. Table 4 shows the interpretation of these ratings.
Table 7 shows that the appearance variable did not change at all during the twelve week analysis, nor was there a difference in the ratings of the products with and without nitrogen (N₂). The other variables showed changes starting in week 6. The sensory value of the product without nitrogen (N₂) dropped from five to four, as shown in Figures 20, 21, 22 and 23. This being the case, it proves that the shelf-life of the product was increased, because the products with nitrogen (N₂) retained higher quality.
Product B has a shelf-life of six months in the market. This value was determined by previous studies conducted by the company. Figures 20, 21, 22 and 23 show that there were sensory changes after this week. The nitrogen (N₂)-containing product had a consistent sensory rating of five, which means that the shelf-life was extended by six months more, so the product can last a year on the market.
It must be understood that the present invention is not restricted to the embodiments described and exemplified herein. As is evident to a person skilled in the art, there are other possible variations and modifications that do not deviate from the spirit of the invention, which is only defined by the following claims.

Claims

A method is claimed for packaging individual products using horizontal flow packaging machines that possess an infeed conveyor that feed products individually into a packaging tunnel that seals the packaging lengthwise along the bottom using sealing media, and then seals the packaging transversally to form individual packages for each product, characterized by the injection of a gas stream into the packaging tunnel before the lengthwise sealing.
The method from Claim 1, characterized because gas is injected by an oval-shaped capillary tube having a triangular tip.
A device is claimed that supplies gaseous fluid in horizontal flow packaging machines that possess an infeed conveyor that feed products individually into a packaging tunnel that seals the packaging lengthwise along the bottom using sealing media, and then seals the packaging transversally to form individual packages for each product, characterized because it contains an oval-shaped capillary tube with two (2) holes to allow inert gas to flow out in a turbulent pattern in the direction of the machine.
The device from Claim 3, characterized because the capillary tube has a triangular tip that directs the flow of gas in the packaging tunnel.
The device from Claim 3, characterized because the tip of the capillary tube rests at the same level as the feeding conveyor of the line of products.
The device from Claim 3, characterized because the tip of the capillary tube is flat.
The device from Claim 4, characterized because the inert gas is nitrogen (N₂).
The device from Claim 3, characterized because the capillary tube has universal hose couplings.