Palm oil is a vegetable fat widely used in the food industry (it represents the basic component of the world's most famous chocolate and of most baked goods, cookies, cakes and snacks) and its widespread use is due to its peculiarities. Texture, fragrance, taste neutrality, the ability to lengthen the preservation of the products and maintain their chemical and physical stability even at high temperatures and, last but not least, its relatively low cost, represent some of them.
The present idea deals with a method for processing a semi-liquid vegetable fat (e.g. palm oil) in its "plasticized" form directly into the industrial or craft kneaders usually dedicated to the production of doughs for bakery products. The physical state of vegetable fats, said "plasticized", refers to the structure in which the triglycerides molecules are solidified predominantly in the form of β’ crystals (orthorhombic lattice). This form is preferred in the standardized technological processes as it offers the best performance in terms of easy workability and plasticity required for the production of industrial doughs. In fact, it is directly related to the efficiency of the physical leavening aimed to maximize the incorporation of air into the dough through its manufacture process. Specifically, it has been experimentally proved by X-ray diffraction techniques that warm pre-emulsified vegetable fats (e.g. palm oil at 35-45 °C), can be transformed into the desired crystallized form through the realization of a two-step cooling process obtained by adding a suitable amount of a cryogenic substance able to "plasticize" a determined mass of fat. Cryogenic substances mean liquid nitrogen or carbon dioxide snow, which can be injected into the kneaders through appropriate dispensers supplied by industrial mixers marketed by companies in the sector. Moreover, the presence of small amounts of appropriately selected and tested "food grade" emulsifiers, allows for stabilization of the liquid-solid interface between the liquid fraction of low melting triglycerides and the solid nuclei of β’ micro-crystals, thus favouring a better dispersion of the latter into the oily liquid phase. The design idea is ready to address the scale-up phase aimed at the development of a prototype process, which will provide the possibility to control the efficiency of the "plasticization" of vegetable fat directly into the mixer (in situ) and calibrated for substantial quantities of raw material.
Currently, the technology dedicated to the production of solid fats for the food industry is based on the use of plants (crystallizers and plasticizers) able to produce plastic shortenings from vegetable refined oils. In particular, the industrial plants existing on the market are generally represented by Scraped Surface Heat Exchangers. However, the high cost of maintenance of these facilities coupled to the elevated cost of the plants themselves, could represent a serious obstacle for farmers wishing to plasticize the semi-liquid palm oil "in situ" in place of buying a more expensive shortening in the "plasticized" final form. Therefore, the present invention proposes an alternative technological process, which allows obtaining "plasticized" vegetable fat, in particular palm oil, avoiding the use of expensive plants, such as industrial crystallizers and plasticizers. The invention uses as input a less expensive raw material, such as the semi-liquid palm fat, in place of its "plasticized" form, which would lead to a cost reduction of about 8-10% for the company, with possible abatement in economic terms of the final product cost along with the entire production chain. The realization of this innovative process provides: a) economic benefits, thanks to the use of raw materials obtained at lower cost; b) high-qualitative product, associated with the improvement of fat stability solidified directly into the kneader; c) better streamlining capacity of the various stages of industrial production of bakery products, adapted to the seasonal requirements of the company. In particular, the opportunity to "plasticize" the fat directly into the kneader would lead to a considerable reduction of the thermostating costs necessary to storage large fat reserves at temperatures lower than 20°C if purchased as "plasticized". The proposed process has been tested for low amounts of palm oil compatible with craft kneaders of small size (1-5 kg of final dough) but it could be also extended to other vegetable oils such as olive, corn, sunflower and "high oleic" sunflower. A possible critical point may be represented by a significant lengthening of the average processing time required to produce one dough (e.g. for biscuits) of about 0.5 tons, from the common 5-10 min up to 15-20 min, including the time needed for the preliminary "plasticizing" phase.