Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Foam or foamable type
Reexamination Certificate
1997-07-09
2004-09-21
Bhat, N. (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Foam or foamable type
C426S656000, C426S660000
Reexamination Certificate
active
06793952
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention relates to a process for the preparation of a food product containing AFPs and to food products containing AFPs.
BACKGROUND OF THE INVENTION
Anti-freeze peptides (AFPs) have been suggested for improving the freezing tolerance of foodstuffs.
Antifreeze proteins have been described in the literature, see for example Marilyn Griffith and K. Vanya Ewart in Biotechnology Advances, Vol 13, No 3, pp 375-402, 1995.
Antifreeze properties generally possess one or more of the following properties: thermal hysteresis, inhibition of ice recrystallisation, control of ice crystal shape and interaction with ice nucleators.
Thermal hysteresis is the best known property of AFP's and the property is normally used to test for the presence of AFP's. Thermal hysteresis results from a lowering of the apparent freezing temperature of a solution containing a thermal hysteresis active AFP without affecting the melting temperature. The identification of sources of AFP by thermal hysteresis tests is widely described in the literature, see for example John G Duman in Cryobiology 30, 322-328 (1993).
Inhibition of ice recrystallisation is another property of AFPs. This activity is also referred to as ice crystal growth suppression. This property can be tested by comparing at a certain point in time the ice crystal size of crystals in the presence of AFP and in the absence of AFP. The application of this method in the testing of fish AFPs is described in U.S. Pat. No. 5,118,792 (DNA Plant Technology Corporation)
A third property of AFPs is their ability to influence the shape of ice crystals. This property stems from the selective binding of AFPs to certain faces of the ice crystal and therewith limiting crystal growth in certain directions. The presence of ice crystals having an hexagonal bipyramid shape is then considered indicative of the presence of AFP. This method is for example described for testing the activity of extracellular winter rye AFPs in WO 92/22581 (University of Waterloo).
A fourth property of AFPs is their ability to inhibit the activity of ice nucleating substances. This interaction between and AFP and an ice nucleator may for example result in increased thermal hysteresis. This property is for example tested in WO 96/40973 (University of Notre dame du Lac)
AFPs have been suggested for improving the freezing tolerance of products. Many applications have been suggested in this context.
For example AFPs have been suggested for enhancing the cryopreservation of biological materials (WO 91/12718, Agouron Pharmaceuticals, WO 91/10361, The Regents of the University of California). Also AFPs have been suggested to prevent leakage from liposomes e.g. in cosmetic or pharmaceuticals (see WO 96/20695). A further possible application is to increase the freezing tolerance of plants by including therein (or transgenetically producing therein) an AFP (See J. Cell. Biochem. Suppl. vol. 14e, 1990, page 303 XP002030248, Lee et al, abstract R228). Also fish AFPs have been suggested for use in food products for example in frozen yoghurt or ice cream (U.S. Pat. No. 5,620,732 Pillsbury and WO 96/11586, HSC Research and development limited partnership).
Up till now, however the use of AFPs has not been applied on a commercial scale. Applicants are of the opinion that one of the reasons for the lack of commercial implementation is that although many AFPs have been described, in practice the implementation in actual commercial products encounters serious problems.
Applicants have found that one of the key reasons for these problems is that out of the great number of AFPs that have been described in the literature only a limited set of AFPs can suitably be applied for each application; also applicants have found that this selection of suitable AFPs is dependent on the desired application and/or product attributes to be achieved.
WO 90/13571 discloses antifreeze peptides produced chemically or by recombinant DNA techniques. The AFPs can suitably be used in food-products such as ice-cream. Example 3B shows modified ice-crystal shapes if a water-ice mixture is frozen into a film in combination with 0.01 wt % of AFP.
WO 92/22581 discloses AFPs from plants. This document also describes a process for extracting a polypeptide composition from extracellular spaces of plants by infiltrating leaves with an extraction medium without rupturing the plant cells.
WO 94/03617 discloses the production of AFPs from yeast and their possible use in ice-cream. WO 96/11586 describes fish AFPs produced by microbes.
The present invention aims at providing frozen food products having a relatively hard and brittle texture, said texture being maintained upon prolonged storage at low temperatures.
A number of literature places have suggested that AFPs may potentially be used for favourably influencing the textural properties of frozen confectionery products such as ice cream. However most of these documents do not provide a teaching how these favourable properties can actually be achieved in practice.
WO 96/11586 (not pre-published) teaches the application of fish antifreeze polypeptides in frozen fermented food products. Hard and brittle products are not mentioned.
WO 96/39878 (not pre-published) describes the application of AFP in ice-cream by using a specific freezing process. Suitable AFPs for this application may be derived from blood and muscle tissue of antartic fish, artic fish, worms and insects. Again hard and brittle products are not mentioned. Surprisingly it has been found that AFPs can conveniently be incorporated in frozen food products to result in the desired product properties as long as the product and processing conditions are varied such that the ice-crystal shape satisfies specific requirements.
Accordingly in a first aspect, the invention relates to a process for the production of a frozen food product comprising AFP, wherein the conditions are chosen such that the ice-crystals in the product have an aspect ratio of more than 1.9, preferably from 1.9 to 3.0.
If food products are frozen, ice-crystals are formed throughout the product. If AFPs are included in food products to be frozen this generally may lead to a favourable change in ice-recrystallisation properties. Aggregation of the ice-crystals of AFP containing products may cause the brittleness of the product.
Many consumers are in favour of relatively hard and brittle frozen food products or ingredients thereof such as ice-cream or water-ice. For example crispy water-ice can be used as an attractive ingredient in frozen confectionery products, also relatively hard ice-cream is liked by a large group or consumers.
Surprisingly we have found that AFPs offer the opportunity to formulate frozen food products which on the one hand are relatively hard and brittle and on the other hand have improved ice-recrystallisation inhibition properties. Applicants have found that surprisingly this advantageous combination of properties can be achieved if the aspect ratio of the ice-crystals in the product is above 1.9, preferably between 1.9 and 3.
The aspect ratio of ice-crystals is defined as the ratio of the length and the breadth of the ice-crystals. An aspect ratio of above, preferably between 1.9 and 3 corresponds to elongated ice-crystals, which are not rounded in shape. The aspect ratio of crystals can be determined by any suitable method. A preferred method is illustrated in the examples. Preferably the ratio is between 2.0 and 2.9, most preferred between 2.1 and 2.8.
Preferably the frozen product of the invention are brittle. Preferably the minimum layer thickness at which fracture behaviour can be observed is less than 10 mm, more preferred from 1 to 5 mm. Fracture behaviour can either be measured by preparing layers of varying thickness and determining at which minimum thickness fracture behaviour occurs or calculated from the Young's Modulus as described in the examples.
During the formulation and subsequent freezing of food products several parameters can influence the aspect ratio of the ice-crystals t
Fenn Richard Anthony
Needham David
Smallwood Keith
Bhat N.
Good Humor-Breyer's Ice Cream, division of Conopco, Inc.
McGowan, Jr. Gerard J.
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