FIELD OF THE INVENTION

The present invention relates generally to food freshness sensor. More particularly, relates to a condensation barrier layer for reducing condensation effect on the food freshness sensor.

BACKGROUND OF THE INVENTION

Food packaging industry is important nowadays as to provide a good and safe quality of food to consumers. By having a good packaging, it may prevent deterioration in the quality of foods and beverages. The good packaging also may contribute to an efficient distribution, sales and consumption. Food packaging commonly is designed to contain and protect foods, to provide required information about the food, and to make food handling convenient from distribution to consumer’s table. However, primary function of food packaging is to preserve the food and to provide safe delivery of food products until consumption.

For raw material food such as meat, poultry and vegetables, the delivery process from slaughter and processing plants in refrigerated trucks can be kept as cold as -17 °C. Even in lower range of temperature, the food may not be solid frozen. The range of that temperature is considered as a semi-frozen or hard chilled state, which may maintain some moisture to the food as well as tissue of the product. While in a home refrigerator, the temperature can be set as low as 4 ⁰ C and below. Therefore, more moisture will seep out from the product. The presence of moisture in the food packaging may accelerate the deterioration of freshness of the food particularly raw food.

In order to determine the quality and safe product of the food delivery, Malaysia patent application PI 2017000562 has developed a food freshness sensor for determining in situ freshness of the food stored in a food packaging that releases volatile organic compound (VOC). The system comprises of a food freshness sensor affixed to an interior of the food package comprising a gas permeable layer, a sensor adhesive and a pH sensitive biofilm sandwiched therebetween, and a processing engine for measuring and analyzing the color of the pH sensitive biofilm as detected by a user using an image capture device to determine a food freshness level that commensurate a pH value of the food thereof. By way of background, US 2004/0121051 A1 patent application presented a moisture barrier for foods. The patent application‘1051 disclosed a hydrocolloids used as a barrier in multi- component food systems for the inhibition of moisture migration and methods for using the barrier are disclosed. The hydrocolloid can be applied as a powder. The hydrocolloid containing barrier is able to inhibit the migration of moisture across the system, thereby improving the shelf life of the food product, as well as enhancing the ability of the product to survive freeze/ thaw cycles. In doing so, the organoleptic qualities of the food system are enhanced.

A need therefore exists for an improved condensation barrier layer and method thereof for determining in situ freshness of food in food freshness sensor thereby overcoming the problems and shortcomings of the prior art. Although there are few condensation barrier and method of preparing the same in the prior art, for many practical purposes, there is still considerable room for improvements.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

It is an object of the present invention to provide a condensation barrier layer in a food freshness sensor to avoid false result interpretation during freshness detection.

Accordingly, the present invention provides a condensation barrier layer having a modified kappa-Carrageenan by way of cross-linking with an ionic salt to form an ionic crosslink network which is relatively more stable, rigid and less hydrophilic.

Preferably, the kappa-carrageenan is a hydrophilic polymer.

Preferably, the ionic salt is selected from a group of potassium sulfate.

Preferably, the thickness of the condensation barrier layer is in between 0.48mm to 0.52mm. In accordance with another aspect of the present invention, a method of preparing a condensation barrier layer for reducing condensation effect in a food freshness sensor is provided.

The method of the present invention comprises the steps of dissolving kappa-carrageenan in distilled water; preparing hot potassium sulfate; pouring the kappa carrageenan solution into the potassium sulfate; stirring the kappa carrageenan solution; performing solvent casting into petri dish at optimum weight; drying the solution at room temperature; drying the solution overnight in an oven at heating temperature of 37 °C.; and modifying kappa-carrageenan polymer. Preferably, the kappa-Carrageenan is modified by cross-linking the k-Carrageenan with an ionic salt.

Preferably, the kappa-Carrageenan is distilled at heating temperature of 80 °C.

Preferably, the potassium sulfate is 0.1M and ratio with the k-Carrageenan is 1:3.

Preferably, the kappa-Carrageenan solution is stirring at a speed of 1400rpm for 30 minutes. In another embodiment of the present invention, the method of assembling a condensation barrier layer into a food freshness sensor comprising the steps of applying a protection layer on top of a label layer; attaching a biofilm at the bottom of label layer; inserting the condensation barrier layer at the bottom of the biofilm; and attaching a gas permeable layer at the bottom of the condensation layer. It is therefore an advantage of the present invention that detect freshness of any food accurately by implemented the condensation layer in between of the food freshness sensor.

The foregoing and other objects, features, aspects and advantages of the present invention will become better understood from a careful reading of a detailed description provided herein below with appropriate reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: Figure 1 illustrates a condensation barrier layer in between a food freshness sensor according to one embodiment of the present invention.

Figure 2 illustrates a cross layer section of a condensation barrier layer in between a food freshness sensor according to one embodiment of the present invention.

Figure 3a is a diagram of chemical reaction of kappa Carrageenan and potassium sulfate according to one embodiment of the present invention.

Figure 3b is a diagram of crosslink structure of kappa Carrageenan and anion potassium according to one embodiment of the present invention.

Figure 4 is a flow diagram depicting a steps of fabricating a condensation barrier layer according to one embodiment of the present invention. Figure 5 is a flow diagram depicting a steps of assembling the condensation barrier layer into the food freshness sensor according to one embodiment of the present invention.

It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numberings represent like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The above mentioned features and objectives of this invention will become more apparent and better understood by reference to the following detailed description. It should be understood that the detailed description made known below is not intended to be exhaustive or limit the invention to the precise disclosed form, as the invention may assume various alternative forms. On the contrary, the detailed description covers all the relevant modifications and alterations made to the present invention, unless the claims expressly state otherwise.

According to one preferred embodiment, the present invention provides a condensation barrier layer (108) for reducing condensation effect in a food freshness sensor (100) in a food industry. The food freshness sensor (100) as referred in figure 1 comprising protection layer (102), label layer (104), biofilm (106), and gas permeable layer (110). The food freshness sensor further comprising a condensation barrier layer (108) in between the biofilm (106) and the gas permeable layer (110). The food freshness sensor (100) may be affixed to an interior of the food package in which the food is served.

Biofilm (106) in the food freshness sensor (100) is fabricated using hydrophilic polymer whereby the hydrophilic polymer consists of natural dye that will change color based on pH condition. The moisture exists in the food, e.g. chicken or meat packaging will condense at the gas permeable layer (110) and cause the biofilm (106) to wet. Hence, physical appearance of the biofilm (106) will be affected and may cause a false result interpretation during capturing image of the food detection. Furthermore, dye immobilized in the biofilm (106) will leach out and staining the food for in-contact application of the food freshness sensor (100). To avoid the moisture effect, the condensation barrier layer (108) is sandwiched in between of the biofilm (106) and the gas permeable layer (110) as referred in figure 2.

The condensation barrier layer (108) according to an embodiment of the present invention comprises of hydrophilic polymer layer. Preferably the hydrophilic polymer is selected from a group of kappa-carrageenan (k- Carrageenan). The k-Carrageenan structure comprises of hydroxyls and sulfate, whereby when the k-Carrageenan structure is in-contact with water, it will swell and gradually dissolve into the water. The k-Carrageenan is a food grade compatible material, thus it is widely used in food industry.

For performing the condensation barrier layer (108), the k-Carrageenan is modified by way of crosslinking with an ionic salt to form an ionic crosslink network by interaction between the K-Carrageenan and sulfate group. The crosslinking network in the modified polymer will cause the network become more compact and hence produced a cross-linked films which is more stable, rigid and less hydrophilic. The ionic salt is preferably selected from a group of potassium sulfate (K ₂ SO ₄ ). The condensation barrier layer (108) has an optimum thickness of about 0.48mm to 0.52mm.

To give a clear picture about the modifying reaction, a chemical reaction in Figure 3a shows the reaction between the k-Carrageenan and the potassium sulfate, K2SO4. Ion Potassium, K+ from K2SO4 interacts with negative charge sulfate groups in the k-Carrageenan to form the ionic crosslink networks that are able to produce more compact structure. Crosslink structure of k-Carrageenan with ion K+ as shown in Figure 3b produces a film which is more stable, rigid and less hydrophilic.

In one of a preferred embodiment, a method (200) of preparing the condensation barrier layer is shown in Figure 4. The step of preparing the condensation layer begins with dissolving 1.5% - 2% w/w of the k-Carrageenan in distilled water at a heating temperature of 80 °C (210). Following that, a hot potassium sulfate 0.1M is prepared with preferably 1:3 ratio with the k-Carrageenan (220) thereby allowing the k-Carrageenan solution to be poured into the potassium sulfate (230).

Subsequently, the combination of k-Carrageenan solution and the potassium sulfate are stirred at a speed of 1400rpm for about 30 minutes (240). The solution is maintained at the temperature of 80 °C. A solvent casting is conducted at this stage to form into petri dish at an optimum weight, whereby the petri dish is a base for casting the condensation barrier layer. The optimum weight used in this step is preferably a value which comes from the outcomes of the process; i.e. within range of 35g to 45g in weight excluding the weight of petri dish. Modifying the k-Carrageenan polymer will be prepared in accordance to an appearance of a medium dimensional features; i.e. label sticker with windows.

Hereafter, the solution is then let to dry at a room temperature for 2 hours (260). The drying of the solution at the room temperature for 2 hours is a pre-step to homogenize and stabilize an outcome material. This is to avoid shocking state condition when higher temperature is applied. The solution is then kept to be drying overnight in an oven at heating temperature of 37 °C (270). In addition to this step, increase in temperature and drying time are the second step of homogenizing and stabilizing the material. The oven is used for controlling environment’s temperature so as to eliminate any other substituent from surrounding environment affecting the process. The kappa-Carrageenan solution is then modified according to the predetermined appearance in the medium dimensional features. Modifying process takes place when solvent casting method is applied, via crosslinking the k-Carrageenan with K ₂ SO ₄ . As a result, an ionic crosslink networks is formed by the interaction between K+ ion with the sulphate group. This crosslinking will cause the networks to become more compact and produce crosslinked film which is more stable, rigid and less hydrophilic. The condensation barrier layer (108) is inserted in between bio film (106) and gas permeable layer (110) to prevent the moisture from being in contact with the biofilm (106). By utilizing the ionic crosslink network from the modifying process, it will reduce the water contact with the biofilm.

In another embodiment of the present invention, the condensation barrier layer (108) is assembled into the food freshness sensor (100) in a following step as in Figure 5. The protection layer (102) is applied on top of the label layer (104) at an opening window of the food packaging (320). Such protection layer preferably but not limited to biaxial-oriented polyethylene terephthalate (BoPET). The protection layer (102) acts as a thin strip to form an airtight seal between the packaging wrap and adjacent structure of the label layer (104). Further to that, the biofilm (106) is attached at the bottom of the label layer (104) at the opening window (340). On top of the label layer (104) surface is an adhesive to stick the sensor (100) attached to the packing wrap.

Then, the condensation barrier layer (108) is inserting (360) in between of biofilm (106) and the gas permeable layer (110), wherein the gas permeable layer (110) is attached (380) at the bottom of the condensation barrier layer (108). The biofilm (106) used in the food freshness sensor (100) is formed from a biopolymer preferably but not limited to K-Carrageenan group. The thickness of the biofilm (106) is between 44pm to 52 pm. The natural dye of the biofilm (106) will change color based on the pH condition in the food packaging, whereby the pH range is in between pH 5.5 to 6.5.

Upon implementing the condensation barrier layer (108) in between of the biofilm (106) and the gas permeable layer (110), the condensation water or moisture formed from the condensation process is prevented from being in contact with the biofilm (106) in the food freshness sensor (100). The terms“a” and“an,” as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term“another,” as used herein, is defined as at least a second or more. The terms“including” and/or“having,” as used herein, are defined as comprising (i.e., open language). While this invention has been particularly shown and described with reference to the exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.