PRODUCTION OF POLY ALPHA-1,3-GLUCAN FORMATE FOOD CASINGS

Abstract

An extrusion process for making a poly alpha-1,3-glucan formate food casing is disclosed.

Claims

1. A process for making a poly alpha-1,3-glucan formate food casing comprising: (a) dissolving poly alpha-1,3-glucan in a solvent composition comprising formic acid to provide a solution of poly alpha-1,3-glucan formate; (b) extruding the solution of poly alpha-1,3-glucan formate into a coagulation bath to make a tube-shaped wet gel; (c) optionally, washing the tube-shaped wet gel with water; and (d) removing the water from the tube-shaped wet gel to form a poly alpha-1,3-glucan formate food casing.

2. The process according to claim 1, wherein the coagulation bath comprises water.

3. The process according to claim 2, wherein the water contains a dilute aqueous base.

4. The process according to claim 1, further comprising the solution of poly alpha-1,3-glucan formate in (b) is coextruded over an extruded food product into a coagulation bath to make a tube-shaped wet gel covering an extruded food product.

5. A poly alpha-1,3-glucan formate food casing made according to claim 1 or claim 4.

6. A food casing comprising poly alpha-1,3-glucan formate.

7. The food casing according to claim 6, wherein the food casing has a breaking stress from about 10 to about 100 MPa.

8. A food casing comprising poly alpha-1,3-glucan formate covering a food product.

Description

EXAMPLES

[0053] The present disclosure is further exemplified in the following Examples. It should be understood that these Examples, while indicating certain preferred aspects herein, are given by way of illustration only. From the above discussion and these Examples, one skilled in the art can ascertain the essential characteristics of the disclosed embodiments, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt the disclosed embodiments to various uses and conditions.

The following abbreviations were used in the Examples

[0054] DI water is deionized water; MPa is megapascal; DPw is weight average degree of polymerization.

General Methods

[0055] Degree of Polymerization (DPw) was determined by size exclusion chromatography (SEC). The molecular weight of a poly alpha-1,3-glucan can be measured as number-average molecular weight (M.sub.e) or as weight-average molecular weight (M.sub.w). The degree of polymerization can then be expressed as DP.sub.w (weight average degree of polymerization) which is obtained by dividing M.sub.w of the polymer by the weight of the monomer unit, or DP.sub.n (number average degree of polymerization) which is obtained by dividing M.sub.n of the polymer by the weight of the monomer unit. The chromatographic system used was Alliance 2695 liquid chromatograph from Waters Corporation (Milford, Mass.) coupled with three on-line detectors: differential refractometer 410 from Waters, multiangle light scattering photometer Heleos 8+from Wyatt Technologies (Santa Barbara, Calif.) and differential capillary viscometer ViscoStar from Wyatt. The software packages used for data reduction were Empower version 3 from Waters (column calibration with broad glucan standard, DR detector only) and Astra version 6 from Wyatt (triple detection method without column calibration). Four SEC styrene-divinyl benzene columns from Shodex (Japan) were usedtwo linear KD-806M, KD-802 and KD-801 to improve resolution at low molecular weight region of a polymer distribution. The mobile phase was N,N- Dimethyl Acetamide (DMAc) from J. T Baker, Phillipsburg, N.J. with 0.11% LiCl (Aldrich, Milwaukee, Wis.). The chromatographic conditions were as follows: temperature at column and detector compartments was 50 C, temperature at sample and injector compartments was 40 C, flow rate was 0.5 ml/min, injection volume was 100 l. The sample preparation targeted 0.5 mg/mL sample concentration in DMAc with 5% LiCl, shaking overnight at 100 C. After dissolution, polymer solution can be stored at room temperature.

[0056] Thickness of the food casing was determined using a Mitutoyo micrometer, No. 293-831.

[0057] Preparation for Tensile Testing

[0058] Dry films were measured with a ruler and 2.57.6 cm strips were cut using a comfort loop rotary cutter by Fiskars, No. 195210-1001. The samples were then transported to the testing lab where room conditions were 65% relative humidity and 70 F.+/2 F. The sample weight was measured using a Mettler balance model AE240.

[0059] Wet films were measured with a ruler and 2.57.6 cm strips were cut using a comfort loop rotary cutter by Fiskars, No. 195210-1001. The samples were then transported to the testing lab in a water bath where room conditions were 65% relative humidity and 70 F.+/2 F. The wet sample weight was measured using a Mettler balance model AE240. The sample was left to soak in the water bath until right before testing.

[0060] Tensile Properties were measured on an Instron 5500R Model 1122, using 2.5 cm grips, and a 2.5 cm gauge length, in accordance with ASTM D882-09. Breaking stress was reported in MPa and maximum strain was reported in %.

Preparation of Poly Alpha-1,3-Glucan

[0061] Poly alpha-1,3-glucan, using a gtfJ enzyme preparation, was prepared as described in the co-pending, commonly owned U.S. Patent Application Publication Number 2013-0244288 which was published on Sep. 19, 2013, the disclosure of which is incorporated herein by reference.

Materials and General Methods

[0062] Formic acid was obtained from Sigma Aldrich (St. Louis, Mo.). Glycerol was obtained from Acros Chemicals.

[0063] Polymer Solution Preparation

[0064] Poly alpha-1,3-glucan polymer powder was dried in a vacuum oven at 40 C. overnight.

[0065] A glucan formate polymer solution containing 10% glucan with a DPw of 1250 was prepared by mixing the dried polymer powder with a solvent that contained 95% formic acid and 5% water.

Examples 1a and 1b

Process for Making a Poly Alpha-1,3-Glucan Formate Food Casing

[0066] There are multiple ways to make a poly alpha-1,3-glucan formate tube-shaped casing, two of them are described here. While a tubular casing can be made by extrusion through an annular die into a coagulation bath, due to lack of proper equipment alternate methods are demonstrated here.

[0067] Example 1a was prepared as follows. Poly alpha-1,3-glucan polymer (DPw 1250) was mixed in 95% formic acid and 5% water to make a 9 wt % polymer solution and stirred overnight. The polymer dissolved completely to make a clear, viscous solution of poly alpha-1,3-glucan formate. Ten to fifteen ml of this solution was poured onto a glass plate and spread to cast a thick cast wet film. A glass test tube (dimensions 2 cm diameter11.5 cm long) was rolled over the cast wet film to transfer the cast wet film to the glass tube. The coated test tube was then immediately immersed in water for 2 minutes to coagulate the solution to form a tube-shaped wet gel. The coated tube with the tube-shaped wet gel was then immediately placed into consecutive baths of deionized water until the water pH was neutral. The coated tube with the tube-shaped wet gel was then placed in 10 wt % Glycerol (obtained from Acros Chemicals) solution for 10 mins. The tube-shaped wet gel was then loosened and removed from the test tube and allowed to dry. The final dry tube was 89+/10 micron thick and was transparent.

[0068] Example 1b was prepared as follows. Poly alpha-1,3-glucan polymer (DPw 1250) was mixed in 95% formic acid and 5% water to make a 9 wt % polymer solution and stirred overnight. The polymer dissolved completely to make a clear, viscous solution of poly alpha-1,3-glucan formate. A glass test tube (dimensions 1 cm diameter7.5 cm long) was dipped into this solution and removed to form a coating on the test tube. The coated test tube was then immersed in water for 2 minutes to coagulate the solution to form a tube-shaped wet gel. The coated tube with the tube-shaped wet gel was then immediately placed into consecutive baths of deionized water until the water pH was neutral. The tube-shaped wet gel was then loosened, removed from the test tube and allowed to dry. The final dry tube was 86.4+/2.5 micron thick and was transparent.

[0069] Thus, the Examples above demonstrate a poly alpha-1,3-glucan formate food casing was made as a seamless tube with sufficient mechanical integrity and clarity according to the present disclosure.

Permeable, Shrinking Casings

[0070] The following examples demonstrate that glucan casings allow water to permeate through and be removed from extruded food products. They also show that as the extruded food product shrinks, the casing shrinks with it to maintain a well-formed casing around the extruded food.

[0071] Individual hot dogs (8.0-8.5 g each) were placed on a skewer and dipped into a glucan formate solution, as indicated below. Hotdogs were weighted before and after dipping and again at regular intervals to measure weight loss due to water evaporation. As shown in the Table below, the hotdogs coated with glucan formate (at thicknesses that would be considered typical) lost the same amount of moisture as the uncoated hotdogs. This high degree of permeation would allow water to escape from the meat emulsion during cooking to create the desired texture. It was observed that the coatings shrank with the hotdogs and maintained a tight seal to the hotdogs as the water evaporated from the extruded meat.

Comparative Examples A, B and C

Uncoated Hotdogs

[0072] Comparative Examples A, B & C were uncoated hotdogs, attached to skewers, used here for controlled comparisons. Comparative Examples A & B were left in under ambient conditions, while Comparative Example C was sealed in a polyethylene bag. Weight losses after 7 days are shown in the Table.

Example 2

Process for Making a Poly Alpha-1,3-Glucan Formate Food Casing

[0073] Covering a Food Product

[0074] The hotdog on skewer in Example 2 was dipped in the following solution: 10% glucan (1250 DPw) in 95/5 formic acid/water. The coated hotdog was then immediately placed into water to coagulate the coating. The hotdog was hung under ambient conditions to dry. The 7-day weight loss is indicated in the Table below. This calculation was made assuming that the dry coating weight was 10% of the original wet coating weight. After the 7-day measurement was completed, the hotdog was sliced open and the coating was examined by microscope. It was found to have a thickness that varied between 63-95 microns. Weight losses after 7 days are shown in the Table.

TABLE-US-00001 TABLE 1 Weight Loss 7-Day Example Sample Description Weight Loss Comparative Control #1-no coating 44.8% Example A Comparative Control #2-no coating 45.2% Example B Comparative Control #3-no coating, 1.7% Example C sealed in PE bag Example 2 Coated with glucan formate 44.3%

[0075] Thus, the Table shows that the poly alpha-1,3-glucan formate casings allow water to permeate through and be removed from food products. It was observed that as the food product shrinks, the casing shrinks with it to maintain a well-formed casing around the food product.

Example 3

Poly Alpha-1,3-Glucan Formate Food Casing Strength for Covering a Food Product

[0076] To demonstrate that a glucan formate layer co-extruded with an extruded food product into a coagulation bath would be strong enough to be pulled through a continuous process (including twisting and hanging while still wet), and without availability of standard equipment to co-extrude such products, flat wet gels of glucan formate were made using the following procedure, and mechanical properties of those flat wet gels were tested.

[0077] This 10% glucan (1250 DPw) in 95/5 formic acid/water solution was centrifuged to remove air bubbles. The solution was spread onto a glass plate by pouring a controlled amount of solution onto a glass plate, and then drawn down using a Meyer rod. The solution and the plate was immediately immersed in a water bath until a flat wet-gel was formed. In most instances, the flat wet gel removed itself from the glass. The flat wet gel was then placed in a new water bath to wash off residual formic acid. This washing process was repeated until the pH of the bath remained neutral after the flat wet gel was soaked for 10 minutes. The flat wet gel was removed from the bath. This process produced a smooth, flat wet gel with a thickness of 155 micron. The tensile strength was found to be max strain of 236% and a breaking stress of 6.6 MPa. The flat wet gel appeared colorless and transparent to the human eye while wet.

[0078] Thus, a poly alpha-1,3-glucan formate layer co-extruded with an extruded food product into a coagulation bath would be strong enough to be pulled through a continuous process.