REQUIRE REFRIGERATION

TECHNICAL FIELD

The present invention is directed to ready for consumption food production industry which does not require refrigeration or that can be stored at room temperature, more particularly in production of packed food or in retorting containers processes ready for consumption.

BACKGROUND AND PRIOR ART

The retorting containers or simply retorting, is packaging manufactured with flexible materials pursuing replacement of cans or canned bottles in order to make preservation and manipulation easier and efficient for any kind of food.

Some of the most important features of the retorting containers are that they allow preserving food with the same features and timeframe than the canned food, they are more flexible and light than a can, and refrigerated distribution is not needed, therefore allowing optimizing the storage space as well as reducing shipment, managing, and distribution costs. Also, the retorting containers are safer than a can since they do not have sharp edges and reduce an accident risk in the production process thereof, packaging of a product, as well as an accident risk in the domestic manipulation, since for example, a retorting container can be opened even by hand.

The retorting, either in a bag form, jar or other, is a 3 or 4 films laminate of different materials, for example, polyester, aluminum, polypropylene, and nylon, and resulting resistant to thermic processes as autoclave processing or heating the packed product in a microwave, making it much resistant and durable than a common plastic bag which are prone to suffer damages under high temperatures. The material to make the retorting with, being thermic resistant achieves, for example, more efficient sterilization process than the ones commonly used with a can, due mainly to the retorting walls thickness. Furthermore, being thinner than a can achieves more reduced cooking times in the production process as well as in the domestic treatment, with significant energy savings with no effect in the flavor and/or nutritional value of the packed products, therefore, the retorting is also much more environmentally friendly than any of the other mentioned packaging means.

Also, the retorting is much more versatile in the packaging of the products in different formats and sizes, allowing a greater variety in the presentation of the products and therefore a more powerful and attractive insertion in the market, since for example translucent packaging can be made, allowing also inspection of the product before it can be opened.

One of the problems during the retorting process, or packed food production in retorting containers process, is the air or gas volume that can remain in the area over the content (food) which added to the product water vapor inserted into the container produces that the container pressure increases, which may cause a container deformation during the sealing or sterilization process and eventually the container may explode. A similar problem occurs when it comes to a packaging comprising some rigid sections, wherein an imbalance between the inner and outer pressure of the container during the sterilization process may deform the container, or produce the collapse thereof. The usual manner to solve this problem comprises filling the container with water or liquid as in the case of canned food, using flexible containers (pouch, doypack) and even for example, in the production of sausages (pate), the product is subjected to a prior vacuum process in order to remove the inner air. However, these solutions do not work when the desired food to produce is dry and air spaces remain inside the container, for example, ready for consumption grained rice, or any other food with similar features.

Another critical step of the retorting process is the cooling down after the sealing or sterilization, since not only the container will cool down, also the product that has been already packed. During this process pressure is required to be controlled in order to avoid the container inflating so much, which may also cause the container to collapse or explode.

Therefore, it is important to count with a mechanism that allows controlling the pressure or the pressure balance, during the sterilization process, this way avoiding the explosion, deformation, or collapse of the retorting container, unlike the normal or traditional processes, wherein the pressure control or compensation is made during the cooling down process only and not during the entire sterilization process.

In the prior art, some documents stand out describing industrial processes seeking to give solution to the described problem, however, none of these documents comprises each of the features of the present invention.

For example, the document EP1820410A1 describes a packed products treatment process (paper or paperboard packing) wherein the sterilization is made in an autoclave, and the cooling down step after the sterilization is made as part of the pre-cooling down up to 80°C, and it is during this step wherein air is injected under pressure to maintain the pressure inside the autoclave. This document differs from the present invention in that the air injection is continuous and is limited to the cooling down step, while in the present invention air pulses during the entire sterilization process are considered.

EP2177116A1 describes a method to sterilize a flexible container which contains a liquid food. The method comprises filling the container at a constant speed, packing sealing, and post sterilization thereof. The sterilization is made adjusting the time period counting from when sterilization temperature is achieved until a sterilization value given by a formula is achieved. This also considers the movement of the liquid food inside the packing (ripples) during the sterilization process. This results different to the present invention since this document does not discloses the air injection in none of the sterilization steps, and also it is directed to sterilization of a flexible packing, which is not subjected to the same problems than a packing with rigid sections, for example, a flexible packing does not suffer deformations or collapsing due to imbalances between the inner and outer pressure of the packing.

US5283033A describes a sterilization process for containers or packing that can be deformed. The process comprises maintaining a constant pressure of the container free space during the entire process. The manner of maintaining said constant pressure is based on pressure and temperature measurement from different zones of the place where the sterilization is made. The measurements that are made correspond essentially to temperature, volatile gas partial pressure (vapor) to the highest temperature in which the process will be performed. The method indicates that some of the measured values are introduced into a calculator to determinate the manner for controlling the free space pressure inside the packing. This document also is directed to a packing or flexible containers problem; therefore the solution would not be easily applicable to the problem of the containers with rigid sections, according to the problem that the present invention solves.

EP2145543A1 describes a sterilization process after packing of the product. The process is based on rising the pressure up to a range of 2 to 5 bar (200 to 500 kPa), before increasing the temperature. Once the pressure is reached, the heating step begins, up to 110°C temperatures. Once the sterilization process has finished, during the cooling down, the pressure also maintains the value stablished in the beginning, and it is cooled down until 25°C, from where the pressure is allowed to decrease up to atmospheric pressure. SUMMARY OF THE INVENTION

The present invention comprises a process or method of retorting for food ready to eat, in a particular case, for grains processing, for example rice, quinoa or even cooked pastas containing humidity but at the same time requiring so much air in the container in order to be consumed in its traditional form (grained rice, not a rice soup).

The process consists in subjecting the product previously packed to a predetermined temperature and pressure conditions with water vapor, and to air pulses injection, and vapor release during the sterilization process and/or cooking in order to control the pressure corresponding to the temperature inside the containers that are being processed, which depends on the water quantity and air contained in the container.

DETAILED DESCRIPTION OF THE INVENTION

The present invention corresponds to a sterilization method of packed food in retorting containers.

Particularly, the method comprises the following steps: i. putting food already packed in sealed retorting containers inside of a temperature and pressure sterilization device, wherein at least one of the containers carries inside a temperature sensor;

ii. initiate the sterilization process starting at an initial pressure P ₀ equal to the atmospheric pressure and at an initial temperature T ₀ equal to room temperature; iii. increasing the temperature inside the sterilization device compensating the pressure inside the sterilization device, during the increase of temperature, using air pulses injection and/or vapor purging, in order to maintain the pressure inside the sterilization device within a range of 5 to 35 kPa above or below a predetermined compensated pressure (P _c ) until achieving a maximum sterilization temperature T _M between 115°C and 130°C measured by the temperature sensor inside of the at least one container;

iv. maintaining between 5 and 60 minutes the T _M temperature and pressure within a range of 5 to 35 kPa above or below a predetermined compensated pressure (P _c ) in the sterilization device;

v. cooling down the sterilization device, compensating the pressure inside the sterilization device, during the temperature decrease, using air pulses injection and/or vapor purging, in order to maintain the pressure inside the sterilization device within a range of 5 to 35 kPa above or below predetermined compensated pressure (P _c );

vi. releasing the inner pressure of the sterilization device and cool down until room temperature and pressure are reached.

In a particular embodiment, the predetermined compensated pressure (P _c ) is defined according to the temperature measured inside of the at least one container which carries inside a temperature sensor. More specifically, the compensated pressure P _c corresponds to a pressure between 350% and 200% greater than the water vapor pressure for a temperature from room temperature to 60°C, respectively; between 200% and 50% greater than water vapor pressure for a temperature from 60°C to 100°C, respectively; and between 50% and 40% greater than the water vapor pressure for a temperature between 100°C and 130°C, respectively.

In a particular embodiment, the retorting container is a container with at least one rigid wall.

In a particular embodiment, air pulses injection and/or vapor purging is made when temperatures above 40°C are achieved inside the containers with a product to sterilize.

In another embodiment, the injected air to the sterilization device as air pulses is at room temperature.

In a specific embodiment, the temperature and pressure sterilization device corresponds to an autoclave.

In a particular embodiment, the food is selected from solid food, liquid or thick food, or mixtures thereof, wherein said food contains air. In a more specific embodiment, the solid food is selected from grains, rice, quinoa, wheat, oats, chopped vegetables (carrots, eggplants, potatoes, zucchini, pumpkin, sweet potato, asparagus, artichokes, etc.), meat pieces (chicken, pork, beef, lamb), fish pieces, legumes, beans, peas, lentils, or mixtures thereof. In another specific embodiment, the liquid or thick food is selected from vegetables soups, fruit juices, sauces or purees of fruits such as tomato sauce, mango puree, mashed potatoes. In still another more particular embodiment, the food is selected from solid food and liquid or thick food mixtures, for example soup with noodles and/or chopped vegetables and/or meat pieces, soup with beans, soup with chopped vegetables and/or meat pieces. EXAMPLES

The method of the invention was applied to produce 300 retorting containers of 250cm ³ of capacity. Each container, before being introduced into an autoclave device, was filled with 60 grams of crude rice and 90 grams of water with salt and oil.

The autoclave was set to inject compressed air or purging vapor, in order to maintain the pressure in a predetermined compensated pressure range P _c +/- 5kPa. Once it achieved a sterilization temperature of 121°C, it was maintained for 15 minutes, then proceeding with the cooling down, during this process the pressure inside the autoclave was also maintained in a range of P _c +/- 5kPa.

All the obtained containers after the cooling down were maintained in excellent condition, without any explosion or collapse.

Microbial culture tests were carried out, wherein the content of the containers was maintained sterile for 24 months, stored at room temperature.

INDUSTRIAL APPLICATION

The present invention has application in the food industry, more specifically, in prepared ready to eat food industry, which can be stored at room temperature, and/or refrigeration is not required.