Vacuum infusion for the inclusion of a food supplement into food products

Fecha de publicación: 30/11/2017
Fuente: WIPO Food Portada
A method of vacuum infusion of a supplement in a porous food product comprising treating a porous food product having a majority of pore sizes of less than about 1000 pm in diameter with a supplement having a particle diameter size range less than the pore size range, wherein said supplement is present in a carrier, and said method is performed under suitable conditions and for a suitable time to achieve infusion of the supplement into the food product, the improvement comprising higher levels of supplement incorporation than with other pore size and particle diameter size ranges.
Field of the Invention
The present invention relates to a method and composition for preparing dry pet food products including a specifically formulated dietary supplement. It is particularly related to products containing inactivated probiotics, probiotics, enzymes, Inactivated yeasts, botanical extracts and dairy components.
Animal (and some human) feeds typically are supplied as pellets or pieces ("kibble"). The Pellets are typically formed from a starch and/or protein containing base ingredient, e.g. wheat or com, mixed with a variety of other ingredients. The starch or protein containing base ingredient has a functional as well as a nutritional role in the pellet Its functional role is to bind all other ingredients together and to provide the textural and physical (most importantly the porosity) characteristics of the product.
Binding of ingredients typically occurs because of the gelatinization of starch or the denaturation of protein. Both of these physical / chemical processes are usually carried out at elevated temperature and/or pressure. Those harsh conditions often result in the degradation of labile additives, such as probiotics and other dietary supplements. This problem has been overcome by the cold extrusion process disclosed in WO 2007/059588.
However, the cold extrusion process can be time-consuming and often forms a "bottle-neck" in many processing plants.
Thus, there is a need for an alternative process that will allow the incorporation of labile components into products prepared via other forms of the extrusion process without significant degradation of those components.
It is proposed that the installation of vacuum infusion technology as an adjunct to a standard dry pet food extrusion process will ensure that a heat-labile component may be delivered into the finished product with full functionality, whilst not causing any loss to the production capacity of the processing plant.
Liquid coatings are commonly added to the external surface of extruded products for a number of reasons including:
1) To improve product surface aesthetics (for example, the glossy coatings used on the surface of extruded rice snacks).
2) To improve product flavour (for example, the addition of flavourings greatly enhances the palatability of extruded pet food).
3) To increase the product energy density. (The addition of oils and fats to. the product significantly Increases the metabolizable energy of the product.) 4) To modify the product textural attributes. (The addition of a plasticizer, such as glycerol, to an extruded structure Is one means of producing a "soft" texture.)
5) To allow the post-process addition of active Ingredients or infusates. (Many of the most expensive functional ingredients, such as vitamins, minerals, pigments, etc are also temperature sensitive. Hence post-process addition can result in significant savings on formulation costs.)
The development of the vacuum infusion process is closely linked to the growth of the aquaculture industry. During the 1970's a number of the major feed manufacturers began to utilize extrusion cooking technology to replace the more traditional pellet milling processes. One of the major justifications for this change in processing technology was the deemed improvement in product quality and also the ability to produce feeds with an oil content in excess of 20 %. The initial processing was focused predominantly on single screw extruders (S.S.E.).
Extensive research into the metabolism of various marine species (especially trout and salmon), during the early 1980's, showed that an increase in the Total Fat Content (up to at least 30 %) would be beneficial. It was difficult to add this amount of oil externally on the pellets. The incorporation of this level of fat Into the formulation began to stretch the limits of the extrusion technology and this lead to
the use of Twin Screw Extruders and also Specialty S.S.E.
It was during this period that the Dinnissen Company (Holland) and BP. Nutrition (now known as Nutreco) began to collaboratively develop the vacuum infusion process for the addition of significant levels of fat, post-extrusion. The major benefit of this process was that significantly higher levels of oil could be incorporated into pellets produced via standard extrusion technology.
In order to provide an understanding of how this technology works, we now describe the fundamental processes that are involved in the liquid coating of porous substrates.
The Atmospheric Coating Process
The adsorption of liquid coatings during the atmospheric coating process is primarily controlled by the action of capillary forces. The magnitude of a capillary force is determined by the radius of the capillary, Rp, and by the liquid surface tension, cr. The magnitude of the suction pressure is given by the following simple expression - Pc = 2 * oL * cos ew / Rp
This behaviour is shown in Figure 1 for the absorption of vegetable oil (al = 0.073 N m-1 at T = 25 "C).
The data clearly indicates that the use of very fine capillaries would be beneficial. The resultant flow rate within these fine capillaries would, however, be very slow. The Fanning Equation may be used to estimate the pressure drop associated with thisflow-Pf = 2*f*[I(2Rp)]*p*v2
The provision of larger pores would therefore ensure a more rapid uptake of the liquid coatings, due to the reduced pressure drop within the larger pores. The uptake of suspended infusates would also be promoted by the use of larger pores. The subsequent leakage of liquids from the pellets (a common problem for high oil content products) would, however, also be promoted by the provision of larger pores, since the capillary force will not retain the liquid within the pore.
One of the primary objectives during the manufacture of an expanded extruded product must therefore be to provide an optimal pore size distribution. The gross means of monitoring this product attribute in the manufacturing environment is via the measurement of the product bulk density.
The measurement of bulk density alone is not enough, however. It is also necessary to give consideration to both the sectional expansion and longitudinal expansion. These parameters are shown schematically in Figure 2. These parameters are commonly monitored in an indirect manner in many applications since SEI = D2 / d2 (common to measure the product diameter) and LEI = f (piece length) (common to measure the cutter speed)
Changes to the magnitude of either the sectional expansion index (S.E.I.) and / or the longitudinal expansion index (L.E.l.), even at a constant bulk density or Volumetric Expansion index (V.E.I. = S.E.I. x LE.l.) will result in significant changes to the pore morphology (i.e. the size, number and shape of the pores). These changes to the pellet internal characteristics will have an effect upon the coating characteristics of the product via an atmospheric coating process. The magnitude of the SEI and the LEl are influenced by both the ingredient composition and via the process parameters used during the manufacture of the product.
The Vacuum Infusion Process
As a result of the limitations of both the atmospheric coating process (as outlined above) and the extrusion process (unable to handle large amounts of added il), an alternative means of Increasing the oil content of the finished product needed to be found. This scenario ultimately led to the development of the vacuum infusion process.
The design of a typical vacuum infusion process Is presented In Figure 3.
The mechanism via which the process proceeds is shown schematically in Figure 4 and may be described via the following steps:
1) The required amount of product (typically pre-weighed in a weigh hopper) is charged into a vacuum vessel. The vessel is then sealed.
2) The vessel is then depressurized (a vacuum is drawn) to the required level (typically about 0.2 bar [abs.) or 80% Vacuum). This ensures that most of the air is removed, even from within the pores of the product.
3) The required amount of liquid coating (which may or may not contain a quantity of infusates) is then sprayed into the vessel via a series of nozzles, whilst
the bed of product is being blended via mixing paddles. This ensures that all of the product surfaces become wetted.
4) The vacuum is then slowly released. The Rate of Pressure Rise, 5P, is one of the most important process control points. In order for optimal coating to proceed, the external pressure must increase at a rate that is able to sustain the rate of flow of liquids into the pores. The rate of flow must also not exceed the rate of wetting of the pore inlets,
5) When the pressure within the vessel has returned to atmospheric pressure, the vessel contents may be discharged.
The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge In the art.
Preferred embodiments of the Invention
In one aspect the present Invention provides an improved method of vacuum Infusion of a supplement into a porous food product comprising treating a porous food product having a majority pores of within a certain diameter size range with a supplement dispersed in a carrier wherein the supplement comprises particles the majority of which have a size range which is less than the pore size range, wherein said method performed under suitable conditions and for a suitable time to achieve infusion of the supplement Into the food product, the improvement comprising higher levels of supplement incorporation than with other supplement particle sizes.
The term "a supplement" refers to specifically formulated dietary supplements, particularly particulate supplements, such as products containing probiotics, inactivated probiotics, yeasts, inactivated yeasts, probiotics, enzymes, botanical extracts and/or dairy components.
The probiotics may be selected from one or more of the following group used singly or in combination and used whole or in fractions of the whole bacterial organism: Bacillus coagulans, Bacillus lichenformis, Bacillus subtlis, Bitldobacterium sp., Enterococcus feacium, Lactobacillus acidolphilus,
Lactobacillus casei, Lactobacillus fennentum, Lactobacillus johnsoni, Lactobacillus paracasei, Lactobacillus reuter, Lactobacilius ruminsis, Lactobacillus ,hamnosus, Pediococcus acidifacticii.
The probiotics may be supplied in a live state, that is, capable of metabolizing nutrients and proliferating. Probiotics may also be supplied In an inactivatedd' state, that is, incapable of metabolizing nutrients and proliferating. Where probiotic bacteria are supplied in the inactivated state they still maintain an identifiably approximate physical formation or structure to that manifested in the live state.
The yeasts may include any of the strains of yeasts of the species Saccharomyces cerevisiae used singly or in combination, used whole or in fractions of the whole yeast organism. The yeasts may be supplied in an active state, that is, capable of metabolizing nutrients and proliferating. Yeasts may also be supplied in a 'inactivated' state, that is, incapable of metabolizing nutrients and proliferating. Where yeasts are supplied in the inactivated state they still maintain the same physical formation or structure manifested in the live state.
The prebiotics may include any of the following, singly or in combination: galacto oligosaccharide,lactulose, lactosucrose, fructo-oligosaccharide, raffinose, stachyose and malto- oligosaccharlde.
The enzymes may include any of the following enzymes, singly or in combination: alpha-amylase, beta-amylase, cellulase, alpha-galactosidase, beta-glucanase, beta-glucosidase, glucoamylase, lactase, pectinase, xylanase, lipase and protease.
The term "a porous food product" means a dry or semi-moist food product which has pores or minute passages or interstices which make the product permeable to liquids. Typically this is this Is dried pet food kibble or the like which has been produced by the diret expansion process after extrusion cooking or via the cold extrusion process.
The porous food may comprise a variety of grains, legumes, pulses or vegetables such as amaranth, quinoa, millet, bulgur, wild rice, cous cous, sooji, spelt, kamut, kasha, kaniwa, tapioca and the like.
The term 'a majority pores of within a certain diameter size range" means
substantially 80% of the pores in that size range. Generally the majority of pores in such a product are 200 to 1000pm In diameter.
The term "dispersed in a carrier" means that the particles are kept in suspension via agitation, preferably in vegetable oil and/or tallow.
The term "particles the majority of which have a size range which is less than the pore size range" means that substantially 85% of the particles are less than the pore size range. Preferably, the particles are