EP-3113624-B1 - BIOPOLYMER-BASED PRESERVATION OF PERISHABLE PRODUCTS

Inventors

• OMENETTO, FIORENZO
• KAPLAN, DAVID
• MARELLI, Benedetto
• BRENCKLE, Mark

Dates

Publication Date

20260506

Application Date

20150306

Claims (7)

1. A method for preserving a fruit or vegerable, the method comprising the steps of: (i) providing a fruit or vegetable; (ii) adding a coating to the fruit or vegetable to provide a product comprising the fruit or vegetable with the coating, characterized in that at least a portion of the fruit or vegetable is in direct contact with at least a portion of the coating, wherein the coating comprises one or more layers of amphiphilic biopolymer; (iii) increasing a crystallinity degree within the coating with an annealing process; and (iv) storing the product under a storage condition, such that the fruit or vegetable is preserved, as compared to a fruit or vegetable without the coating under the same storage condition; wherein the relative crystallinity degree is determined by measuring the peak intensity of the amide III absorbance band using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy, wherein the amphiphilic biopolymer is a hydrophobic polypeptide comprising a beta-sheet secondary structure, wherein the hydrophobic polypeptide is or comprises silk fibroin or fragment thereof, wherein the annealing comprises inducing beta-sheet formation in the biopolymer, wherein the beta sheet formation is induced by water annealing.
2. The method of claim 1, wherein the silk fibroin has an average molecular weight of between 3.5 kDa and 350 kDa.
3. The method of claim 1, wherein the silk fibroin has an average molecular weight of between 50 kDa and 350 kDa.
4. The method of claim 1, wherein the silk fibroin has a molecular weight that is lower than wild type silk fibroin.
5. The method of any one of the preceding claims, wherein the step (ii) comprises dip-coating, spray-coating, powder-coating, wrapping, sealing, covering, layering, or any combination thereof, optionally wherein: (a) the step is repeated 2-30 times; or (b) the step is repeated 2-10 times.
6. The method of any one of the preceding claims, wherein the storage condition comprises: (a) refrigeration; and/or (b) room temperature or ambient storage; and/or (c) storing for a duration of 1 day to 1 year.
7. The method of any one of the preceding claims, wherein the fruit or vegetable is preserved in that the fruit or vegetable retains one or more properties, selected from the group consisting of: water content, color, weight, shape, texture, structural integrity, taste, flavour, smell.

Description

BACKGROUND Preservation of perishable goods, food in particular, typically involves preventing the growth of bacteria, fungi (such as yeasts), and other micro-organisms, as well as retarding the oxidation of fats that cause rancidity. Food preservation can also involve inhibiting enzymatic processes, which lead to discoloration and/or changes in texture of the perishable goods. In addition to or concurrent with visual deterioration, maintaining nutritional value and flavor is also an important aspect of food preservation. There are a number of techniques that have been traditionally used to enhance preservation of perishable items. These include, for example, drying, pasteurization, refrigeration, freezing, vacuum packing, salting or curing, sugaring, smoking, chemical additives, pickling, lye, canning and bottling, irradiation, etc. More recently, food coating (sometimes referred to as glazing) has been exploited as a means of enhancing preservation, as well as organoleptic properties. Several classes of biopolymers have been contemplated as coating materials: polysaccharides, proteins, lipids, as well as various combinations of these biopolymers (reviewed, for, example, in: Biopolymers - New Materials for Sustainable Films and Coatings. Copyright © 2011 John Wiley & Sons, Ltd., Editor(s): David Plackett; Print ISBN: 9780470683415; Online ISBN: 9781119994312; CH. 10 "Food Packaging Applications of Biopolymer-Based Films"; CH. 11 "Biopolymers for Edible Films and Coatings in Food Applications"). Polysaccharides and proteins are known to form films with good mechanical properties, but with poor permeability, while the lipids form brittle films but with improved permeability. Coating fruits and vegetables with a waxing material is also a common example. The primary reasons for waxing are to prevent water loss and thus retard shrinkage and spoilage, and to improve appearance. The waxing materials used for such purposes depend to some extent on regulations in the country of production and/or export; both natural waxes (e.g., sugar-cane, carnauba, shellac, and resin) and petroleum-based waxes are used. Wax may be applied in a volatile petroleum-based solvent but is now more commonly applied via a water-based emulsion. Blended paraffin waxes applied as an oil or paste are often used on vegetables. Such techniques are useful for selective products, but not for others. CN 102870873 teaches coating strawberries with silk fibroin to increase shelf stability. KU KUOUNG-JU ET AL:. "«Preparation of a Silk Fibroin Film Containing Catechin and Its Application»", FOOD SCIENCE AND BIOTECHNOLOGY, vol. 17, no. 6, 2008, pages 1203-1206 teaches coating of sausages by silk fibroin films. WO 97/23137 A1 teaches preserving sea food with zein proteins. However, none of these documents discloses either anything specific regarding the presence of a crystalline phase or any specific step in a method related to increasing a crystallinity degree. CN 101 824 225 A describes the formation of edible silk films which are prepared completely separate from the product they may later package. WO 2009/155397 A2 discloses biocompatible silk coatings but not a crosslinking/annealing post-processing technique or any recognition that increasing the degree of crystallinity in the biopolymer may enhance preserving effects. SUMMARY OF THE INVENTION The present invention provides methods for preserving a fruit or vegetable as defined in the claims appended hereto. Other aspects of the invention are also defined in the claims appended hereto. REFERENCE TECHNICAL DISCLOSURE The reference technical disclosure set out below may in some respects go beyond the invention per se as summarized above, and so may also provide technical background for related technical developments, as may be illustrated inter alia in the examples. The reference technical disclosure set out below provides background technical information and is not intended to define the invention as such, but rather to facilitate the understanding and working of the invention while placing it in technical context. Described herein, among other things, are biopolymer-based compositions and methods for the preservation of perishable goods, including food. In particular, the disclosure includes the recognition that certain biopolymers offer structural features that are particularly suited for the production of coating materials for perishable products, without the requirement of added plasticizer to achieve desirable malleability. Accordingly, described herein are safe, simple, and versatile coatings that enhance preservation of various perishable products. In some cases, biopolymer-based coating materials used to preserve the perishables are useful for forming a barrier between a perishable item and one or more elements in its environment. In some cases, such coating materials provide a selective barrier between the perishable item and at least one aspect of its environment. For example, such mater