"Improved rapid rehydration method of vegetable and animal products"

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Technical field

The subject of the present invention is an improved procedure for the rapid rehydration of dried vegetable and animal products for the conserves production in the food industry.

State of the art

Usually, the process that leads to the production of a canned food from the dried raw material is realized by a sequence of steps, some of which are only potential. In particular, starting from an animal or vegetable dried product, the essential and preparatory step, the preparation of a canned food within a industrialized production cycle, is the phase of regeneration and/or rehydration. The latter term refers to the phase that allows the return of freshness and softness of the dried product through a partial or total return of moisture .

The need to detect new processes for the rapid rehydration of dried products used as semi-finished products in the food industry is an extremely important theme, not only to reduce the regeneration time but also to obtain a semi-finished product which is able to provide better quality final product.

In the case of dried vegetable and animal products, the concept of quality is linked to the tissue integrity and consistency, and mainly to the ability to maintain unchanged as much as possible the chemical and physical properties.

To get the best conditions for a good preserved product it is very important that the regeneration phase of the dried product is quickly performed and without excessive thermal stress.

In this way excellent rehydrated products can be obtained for the preparation of products that will be processed with the appertization , as well as IV range products and those products that are directly marketed as rehydrated.

As for current state of the art, the regeneration phase of dried legumes, for example, is carried out by immersing legumes into the water at ambient temperature for a variable time depending on type, humidity degree and size of legumes.

The high cost of these traditional rehydration processes is due to the excessive handling of the product and the long soaking time. This can cause abnormal fermentation, frequently with release of bad odors and a general qualitative deterioration of the finished product.

More modern systems use machineries which reduce the time of rehydration to about an hour, by using alternate cycles of heating and cooling of the dry legume .

In these cycles the product is kept alternatively at high temperatures (98 to 100°C) with fast breaks in the cold water. This method is significantly expensive and also reduces some nutritional properties of the vegetable.

Aims and advantages of the invention

First aim of the present invention is to provide a method to be executed in the regeneration phase of canned food production cycles, reducing the rehydration time in 3 to 9 minutes, depending on the raw material and with absence of any thermal stress. The obtained rehydrated product shows a good texture, firmness and strength. Furthermore, it is able to resist to any subsequent sterilization, stabilization and packaging process without suffering of structural damages and deterioration of the external 75 characteristics that could compromise the consumer liking.

The second aim of the present invention is to obtain a finished product whose nutritional and organoleptic characteristics remain substantially unaltered 80 compared to the properties and characteristics of the original natural product.

Further target of the invention is to realize a procedure able to give a suitable consistency to the vegetable product, without changing its properties.

85 It should be noted that this process can be introduced in the traditional cycles and, in particular, in the regeneration step making only a few changes to the traditional processing lines, avoiding significant additional costs for modifications and/or adaptations

90 to existing plants.

Best mode for carrying out the invention

These results and related advantages are achieved through a procedure to be executed in the cycle of 95 canned food production and more precisely in the product regeneration step, by using the high hydrostatic pressure treatment. This treatment is performed on dried animal or vegetable products using plants capable of generating high hydrostatic

100 pressures which allow the dried products to quickly absorb the necessary water for their rehydration.

According to the present invention, in the regeneration phase of the canned food production cycle it is performed the immersion of the dry product in

105 the regeneration water at a pressure of 300 MPa up to 700-800 MPa (1 MegaPascal equals 10 bar or about 10 atmospheres) depending on the product type to be rehydrated.

The treatment phase with high hydrostatic pressure, 110 according to the present invention, must be performed at the regeneration stage, which means after the calibration phase and before any phase of heating or stabilization by heat, as represented in the flow diagram relevant to the processing of beans (table 1). 115 The method of the present invention is better represented in the example below, given only for a descriptive and not limitative title of the invention itself .

EXAMPLE

120 A sample of dry bean is processed for canned food production .

After calibration, the bean has been processed for the regeneration phase with the procedure referred to in the present invention, using a specific plant able to

125 generate high pressures and to reach 30 °C as operating temperature. The product was immersed into the regeneration water at two different temperatures (20 and 30°C) and exposed to high pressures for times varying from a minimum of three to a maximum of nine

130 minutes.

Table No. 1 shows the percentage of absorbed water by a variety of bean varying the time, temperature and pressure .

135 Table 1: Percentage ofabsorbed water by the time,

at different temperatures and pressures

The same variety of beans with the same chemical and physical characteristics was rehydrated using the known industrial techniques described above: the 140 treatment at different temperature cycles and the traditional immersion system.

Table No. 2 shows the required times and the percentages of absorbed water for the same variety of beans with the cycles system and with the traditional 145 system.

Table 2: Percentage of absorbed water by the time,

with cycles and traditional system

The analysis of the results shows that with the process object of the invention it is possible to 150 reduce the time of rehydration to few minutes ( 3 or 6 ) using pressures of 300-400 MPa and operating at room temperature .

On the other hand, to obtain 100 % water absorption with the traditional method it is necessary to soak 155 the same sample of legume by 480 minute; with the cycles system three cycles are needed for a total of 60 minutes.

Tables No. 3 and 4 show how the application of this method leads to a considerable improvement of the 160 product quality. In fact, compared to the traditional method, the rehydration cycles one results in obvious advantages, due to the very low presence of broken, crushed or cleaved seeds (greater entireness).

Table 4: Amount of proteins in the beans before packing

(stated as a percentage of dry matter).

The final product obtained with the present process, not having been processed to high temperatures, preserves its chemical, physical and organoleptic characteristics (e.g. proteins).