Lee Sung Yong Department of Bioscience and Biotechnology Inhibition of pork and fish oxidation by a novel plastic film coated with horseradish extract

Contents 1. Introduction 2. Objective 3. Materials and Methods 4. Results 5. Conclusion

Introduction Effect of oxidation ► Fresh pork Surface discoloration myoglobin → metmyoglobin (brown color) ► Fresh fish Lipid peroxidation and rancidization polyunsaturated fatty acid (high) → easily attacked oxygen-derived free radical ► The shelf life of fresh meats can be extended by protecting them from discoloration, lipid oxidation, and microbial growth. antioxidant application.

Introduction Advantage of AITCDisadvantage of AITC ► Inhibition of lipid oxidation ► Inhibition of food-poisoning bacterial activity ► Inhibition of growth mold, yeast ► High volatile compound ► Strong pungency Japanese horseradish (Wasabia japonica matsum) Japanese horseradish and AITC Microencapsulation

Objective ► To develop an anti-oxidative packaging film coated with microencapsulated volatile horseradish extract ► To verify the effects of this film on fresh-cut meats for the purpose of prolonging their shelf-life.

► Preparation of film coated with microencapsulated volatile horseradish extract Microcapsule coated on plastic film Ground Japanese horseradish Extract with 80% methanol Add of 1% NaOH with slow stirring Dried in vacuum oven Fig 1. Procedure of film coated with microencapsulated volatile horseradish extract Materials and Methods Mixture of extract + chitosan solution Dried in room temperature Storage test of fresh pork and fish

► Free radical scavenging assay 200 μM DPPH solution in 80% methanol was prepared and each sample dissolved in 80% MeOH 2~1000 ㎍ / ㎖. After 100 ㎕ aliquot of DPPH solution into each wall on 96 well plate, different concentration of each sample was added with 100 ㎕, respectively. And then, incubated at room temperature for a 30 min, the absorbance was measured at 517 nm with Micro-plate Absorbance Reader. ► Identification of AITC from horseradish extract by HPLC ► Determination of volatile compounds release The weigh of the microcapsules was then measured and defind as W m. The release of volatile compounds from the microcapsules was estimated by measuring the weigh W m (t) of the microcapsules that were placed in an Infrared Moisture Determination Balance. ► Determination of volatile compounds size distribution Volumetric size distribution of the microcapsules was determined by light scattering with a 2062-LC particle analyzer with the mean diameter and standard deviation calculated from the cumulative distribution curve. Items Conditions Detector photodiode-array detector (Hitachi Lachrom Elite) Column YMC Pack-Pro C18, 5 ㎛, 250 x 4.6 ㎜ I.D Column temperature 26 ℃ Mobile phase Distilled water/Acetonitrile Flow rate 1mL/min

► Storage test Temperature 5 ℃ Storage periods 9day → Color measurement → Peroxide value → 2-Thiobarbituric acid reactive substance (TBARS) Pork fillet covered with ordinary plastic film Fish fillet covered with ordinary plastic film Pork fillet covered with microcapsule-coated film Fish fillet covered with microcapsule-coated film

Identification of a AITC in horseradish extract by HPLC Results

Free Radical scavenging activities of horseradish extract and Green tea extract ► Horseradish extract was selected as an encapsulated antioxidant mainly due to its volatility.

Size distribution ■ 0.5% of chitosan ▲ 1.0% of chitosan ● 1.5% of chitosan ► Microcapsules of larger size have a thicker chitosan matrix which retards evaporation of volatile horseradish extract.

Time courses of release ◆ control ■ 0.5% of chitosan ▲ 1.0% of chitosan ● 1.5% of chitosan ► Slow release of the volatile antioxidant is necessary for long- period storage. ► Therefore, the preparation of microcapsules with high chitosan concentration increases microcapsule diameter and decreases released.

Changes of a* values (redness) ◆ Pork fillet covered with ordinary plastic film ■ Pork fillet covered with microcapsule-coated film ▲ Fish fillet covered with ordinary plastic film ● Fish fillet covered with microcapsule-coated film

Changes of b* values (yellowness) ◆ Pork fillet covered with ordinary plastic film ■ Pork fillet covered with microcapsule-coated film ▲ Fish fillet covered with ordinary plastic film ● Fish fillet covered with microcapsule-coated film

Changes of peroxide values(POV) ◆ Pork fillet covered with ordinary plastic film ■ Pork fillet covered with microcapsule-coated film ▲ Fish fillet covered with ordinary plastic film ● Fish fillet covered with microcapsule-coated film ► The POV measures primary products of lipid oxidation and is used to determine the oxidative state of lipid-containing foods.

Changes of TBARS values ◆ Pork fillet covered with ordinary plastic film ■ Pork fillet covered with microcapsule-coated film ▲ Fish fillet covered with ordinary plastic film ● Fish fillet covered with microcapsule-coated film ► The TBARS analysis measures the formation of secondary products of lipid oxidation such as malondialdehyde which contribute to the acrid flavor of oxidized oil.

Conclusion  The horseradish-imbued film covering enhanced the stability of both pork and fish by preventing color loss and lipid rancidization.  The release of volatile antioxidants from the microcapsules to the atmosphere in the package could be controlled by adjusting the amount of chitosan added for microcapsule formation.  This film may be a useful tool to prevent oxidation and prolong the shelf-life of fresh-cut foods.

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