Kimchi Packaging Research Articles

Development of smart colorimetric indicators for tracking kimchi freshness by loading aronia extract in agar, κ-carrageenan, and cellulose nanofiber films

Color indicator films incorporating aronia extract powder (AEP) and biopolymers like agar, carrageenan, and cellulose nanofiber (CNF) were developed to monitor kimchi freshness. AEP-containing films showed strong UV-barrier properties, and reduced light transmittance by 99.12 % for agar, 98.86 % for carrageenan, and 98.67 % for CNF-based films. All AEP-films exhibited high sensitivity to pH changes and vapor exposure to ammonia and acetic acid. Color change notably influenced by the polymer type, particularly evident with ammonia vapor exposure, especially in the AEP/carrageenan film. The chemical structure and thermal stability of the biopolymers remained unchanged after AEP-addition. Tensile strength increased by 24.2 % for AEP/CNF but decreased by 19.4 % for AEP/agar and 24.3 % for AEP/carrageenan films. AEP-containing films displayed strong antioxidant activity, with 99 % free radical scavenging in ABTS and ~ 80 % in DPPH assays. Alkalized AEP-indicator films were more effective in detecting color changes during kimchi packaging tests. Among the labels, alkalized AEP/agar film showed the most obvious color change from green-gray (fresh kimchi, pH 5.5, acidity 0.48 %) to pale brown (optimal fermentation, pH 4.6, acidity 0.70 %), and pale violet-brown (over-fermented, pH 3.80, acidity 1.35 %). Alkalized AEP-indicator films offer promising real-time detection of packed fermented foods like kimchi.

Effect of headspace gas composition in kimchi packaging on the quality characteristics of kimchi.

The online version contains supplementary material available at 10.1007/s13197-023-05795-z.

PH-sensitive smart indicators based on cellulose and different natural pigments for tracing kimchi ripening stages

Five natural pigments including water-soluble [butterfly pea (BP), red cabbage (RC), and aronia (AR)] and alcohol-soluble [shikonin (SK) and alizarin (ALZ)] were extracted, characterized, and loaded onto cellulose for preparing pH-sensitive indicators. The indicators were tested for their color response efficiency, gas sensitivity, response to lactic acid, color release, and antioxidant activity. Cellulose-water soluble indicators showed more obvious color changes than alcohol-soluble indicators in lactic acid solution and pH solutions (1−13). All cellulose-pigment indicators exhibited prominent sensitivity to ammonia compared to acidic vapor. Antioxidant activity and release behavior of the indicators were influenced by pigment type and simulants. Kimchi packaging test was carried out using original and alkalized indicators. The alkalized indicators were more effective in showing visible color changes during kimchi storage than the original indicators, and cellulose-ALZ displayed the most distinct color change from violet (fresh kimchi, pH 5.6, acidity 0.45 %) to gray (optimum fermented kimchi, pH 4.7, acidity 0.72 %), and to yellow (over fermented kimchi, pH 3.8, acidity 1.38 %) which followed by BP, AR, RC, SK respectively. The findings of the study suggest that the alkalization method could be used to show noticeable color changes in a narrow pH range for application with acidic foods.

Development of a calcium hydroxide–dye kimchi ripening indicator and its application in kimchi packaging

Intelligent packaging that provides real-time information on food quality is useful for consumers. We developed a kimchi ripening indicator that can determine the ripeness of kimchi inside packaging and evaluated its applicability and limitations. The indicator was made using calcium hydroxide, which captures CO2, and four pH-sensitive dyes (cresol red, bromothymol blue, bromocresol purple, and methyl red). Fourier-transform infrared spectra of the prepared powders showed shapes similar to that of calcium hydroxide, and the dyes were evenly distributed on the calcium hydroxide surfaces. When the developed indicators were evaluated for kimchi packaging application, the indicator made from synthesized calcium hydroxide and bromothymol blue was the most reliable and clearly reflected useful kimchi ripening information. The indicator developed in this study is judged to be practically usable at temperatures of 4–15 °C. However, its usefulness is limited in that the seller cannot change the packaging capacity or kimchi capacity.

Evaluation of Deodorization Capabilities, Morphologies, and Thermal Stabilities of Baking Soda, Charcoal, Coffee, and Green Tea for Kimchi Packaging Application

We evaluated the applicability of baking soda, charco‘al, coffee, and green tea as a natural deodorant in Kimchi packaging. Moreover, to evaluate the potential usage of these deodorants in packaging materials and confirm their applicability in high-temperature melt-extrusion processing, the thermal stabilities of the deodorants were investigated, and heat-treated deodorants were evaluated in terms of the deodorizing function compared with non-treated deodorants. Aroma patterns were decreased after deodorizing treatment with all-natural deodorants. Dimethyl disulfide, methyl trisulfide, and diallyl disulfide, the most significant odorous Volatile organic compounds (VOCs) of Kimchi, decreased after treatment with the deodorants. In particular, baking soda and charcoal showed the highest efficiency in removing odorous compounds and VOCs from Kimchi, even after high-temperature processing. The acetic acid removal rates for both baking soda and charcoal were 99.9±0.0%. The heating process increases the deodorizing effects of baking soda. Sensory evaluation results showed that there is a significant increase (p < 0.05) in the overall preference for Kimchi samples packaged with charcoal and baking soda. This study provides useful information for the deodorization effects of natural deodorants for Kimchi smell and their applicability for packaging materials.

Development of food packaging materials containing calcium hydroxide and porous medium with carbon dioxide-adsorptive function

Abstract Kimchi packaging can be easily damaged by carbon dioxide generated during fermentation of kimchi, and adsorbents have been developed to overcome the problems of volume expansion and breakage of kimchi packaging caused by carbon dioxide. Here, we examined the applicability of calcium hydroxide and porous medium impregnation for improving adsorbent performance. The developed adsorbents were incorporated into low-density polyethylene to develop packaging materials for kimchi. Notably, packaging materials containing the adsorption powder impregnated with calcium hydroxide and porous medium showed improved mechanical properties and exhibited chemical and physical reactions, resulting in strong adsorptive power and reusability. The mechanical strength of the packaging was weak due to the agglomerative properties of the powder. In kimchi packaging, adsorption packaging did not affect kimchi ripening (p > 0.05). The optimal carbon dioxide concentration in kimchi packaging was 40–55%, and the carbon dioxide concentration could be controlled using the developed adsorption packaging materials.

Critical review on Active Technologies to Regulate the Levels of Carbon Dioxide and Oxygen for Kimchi Packaging

Critical review on Active Technologies to Regulate the Levels of Carbon Dioxide and Oxygen for Kimchi Packaging

Development of a BTB−/TBA+ ion-paired dye-based CO2 indicator and its application in a multilayered intelligent packaging system

Many visual indicators have been developed to provide product quality information through their incorporation into intelligent food packaging systems. In particular, the colorimetric changes undergone by the pH-sensitive dyes that are present in food packages can be used to monitor food quality without destroying the package. However, some difficulties remain in incorporating these dyes into commercial packaging materials because the dyes are often strongly hydrophilic, which leads to the migration of these dyes into food with high water contents through simple contact; additionally, these dyes do not easily mix with the hydrophobic polymers of packaging materials. To overcome these problems, we prepared a bromothymol blue (BTB−)/tetrabutylammonium (TBA+) ion-paired dye and used it to produce a CO2-sensitive intelligent packaging film. Branched polyethylenimine was added to the indicator solution to improve the film’s sensitivity to CO2. The formation of ion pairs was confirmed through Fourier transform infrared spectroscopy, and film characteristics, such as color changes in the presence of CO2 and thermal properties, were examined. Finally, we manufactured multilayered packaging films using the BTB−/TBA+ ion-paired dye and used these to measure CO2 changes in kimchi packaging during the fermentation process. CO2− mediated color changes were easily visible to the naked eye, demonstrating the applicability of our sensor in commercial food packaging films.

Development of a Sulfite-Based Oxygen Scavenger and its Application in Kimchi Packaging to Prevent Oxygen-mediated Deterioration of Kimchi Quality.

A sulfite-based oxygen scavenger (SOS) was developed with sodium metabisulfite and applied to kimchi packaging in an attempt to prevent oxygen-mediated kimchi quality degradation. The results of the oxygen- scavenging capacity test showed that the SOS had a competitive oxygen- scavenging performance in comparison with commercial oxygen scavengers. The kimchi was packaged with and without the SOS and stored over 12 weeks at 0 and 10 °C for an SOS application test. The kimchi treated with the SOS showed a significantly lower (P < 0.05) headspace oxygen and carbon dioxide concentration and pressure inside the packages than the control. The pH and titratable acidity values indicated that the SOS did not retard the kimchi fermentation process. The Hunter L, a, and b values in the kimchi packaged with the SOS were significantly higher (P < 0.05) than those in the control. After 12 weeks of storage, the total aerobic bacteria counts were reduced by 1.32 and 2.97 log CFU/g, lactic acid bacteria counts were reduced by 2.22 and 4.42 log CFU/g, and total yeasts and molds counts were reduced by 1.76 and 3.04 log CFU/g at 0 and 10 °C, respectively, by the SOS compared to those in the control. These results demonstrated that the developed SOS inhibited oxygen-mediated deterioration of the kimchi, but did not affect the kimchi fermentation. Therefore, our SOS can be used as an active food-packaging technology for kimchi quality preservation. PRACTICAL APPLICATION: A newly designed sulfite-based oxygen scavenger was applied in kimchi packaging, and it showed remarkable preventive effects on the kimchi quality deterioration caused by oxygen. Accordingly, it can be used as an active food-packaging technology to maintain kimchi quality during the storage period. Moreover, it can also be effectively utilized in the packaging of other high-moisture foods such as meat, fish, fruits, vegetables, and dairy products.

Application of Physical Gas Absorbers in Manipulating the CO2 Pressure of Kimchi Package.

Physical gas absorption and release of activated carbon or zeolite were used to attain the desired CO2 concentration profile inside a package of kimchi for its dynamic storage and consumption environment. The CO2 adsorption/desorption behavior of different combinations of physical scavengers in the microporous Tyvek sachet was measured at 0, 10 and 20 °C. A combination of highly permeable microporous Tyvek and much less permeable nylon/polyethylene laminate was also examined as a variable to help control the access of CO2 to the physical CO2 absorber. The composition of the absorber and its packing density in the sachet affected the CO2 absorption rate and capacity. Increased zeolite in the Tyvek sachet showed higher CO2 absorption followed by higher CO2 release concomitant with moisture sorption, while activated carbon itself had low CO2 absorption and little subsequent CO2 desorption. Lower temperatures increased the capacity of CO2 absorption and release along with lower CO2 absorption and release rates. A reduction in Tyvek area could decrease the absorption and release rates. An application of a physical CO2 absorber to the kimchi package was tested at 10 °C to show potential for keeping the desired CO2 pressure profile for carbonic cool flavor under tolerable pressure during storage and use. PRACTICAL APPLICATIONS: Physical carbon dioxide absorbers consisting of zeolite and activated carbon inside the gas-permeable sachet can be placed in kimchi packages for time-dependent absorption and release of carbon dioxide, which responds in harmony with the fermentation profile of kimchi. Its practical potential is both to provide a carbonic cool taste of the product and to avoid excessive overpressure in the package through its shelf life when used in kimchi packaging. Its intelligent use may resolve the problem of a dull kimchi taste, which occurs when incorporating calcium hydroxide as the chemical scavenger in the package.

Development of a novel on–off type carbon dioxide indicator based on interactions between sodium caseinate and pectin

Intelligent food packaging systems are a new concept and allow real-time monitoring of food conditions using indicators that are clearly visible to consumers. Among intelligent food packaging types, gas indicators detect changes in gas components in headspaces of food packages. This study aimed to develop a carbon dioxide (CO2) indicator based on reactions of sodium caseinate (NaCas) and pectin. Transparency and pH were measured to confirm the changes in the appearance of the two polymers, and pectin concentrations were optimized for rates of change in transparency. In Fourier transform infrared spectroscopy and confocal laser scanning microscopy analyses, NaCas and pectin suspensions were characterized, and the associations between protein–polysaccharide interactions and pH changes were determined. Subsequently, the developed indicator was applied to kimchi packaging, and changes in pH, titratable acidity, lactic acid bacteria, and CO2 contents of the kimchi packaging were determined and correlated with changes in transparency and pH of the indicator. The results demonstrated a strong correlation between parameters of kimchi and the indicator and warrant the use of visual CO2 indicator in food packaging.

Preparation and properties of sodium bicarbonate‐incorporated LDPE films with deodorizing function for kimchi packaging

Volatile compounds produced during the fermentation of kimchi result in a sour taste and unpleasant odor. Here, we evaluated the utility of sodium bicarbonate (baking soda) as a natural deodorant in kimchi packaging. Baking soda decomposed into sodium carbonate, which showed superior deodorizing effects at 180°C, and aroma patterns were altered after deodorizing treatment with baking soda and heat‐treated baking soda. Moreover, the numbers of off‐odor compounds were decreased when using baking soda or heat‐treated baking soda. In addition, the acetic acid removal rate increased with heat treatment of baking soda. Notably, the external shape and color of baking soda particles were not affected by heating. It was observed that an increase in the content of baking soda in the low‐density polyethylene (LDPE)/baking soda composite films enhanced deodorizing effects. Finally, sensory evaluation confirmed that odor decreased with increased baking soda content. The findings demonstrate the potential value of baking soda and LDPE/baking soda composite films in kimchi packaging and reduction of off‐odors.

Kimchi Packaging Technology : An Overview

This paper provides an overview of kimchi packaging technology, focusing on packaging materials, package design, and active/intelligent packaging technology for kimchi. From a packaging-material standpoint, although various materials have been used to ensure customer satisfaction and convenience, plastic is the most widely used material, in the form of bags, trays, pouches, and rigid containers. Additionally, recent efforts in the kimchi packaging industry have allowed companies to differentiate their products by using different packaging materials and technologies, while simul-taneously improving product safety and quality. On the other hand, the biggest problem in kimchi packaging is excess CO2 production, leading to package expansion and leakage. To alleviate this problem, the use of CO2 absorbers, high CO2-permeable films, and degassing valves, in addition to the use of different packaging systems, has been investigated. Active and/or intelligent packaging systems have been developed, to include active functions beyond simply inert, passive containment and protection of the kimchi product. However, most such approaches are not yet adequately effective to be useful on a commercial scale. Therefore, further studies are needed to resolve the limitations of each technology.

The use of Na 2CO 3-based CO 2 absorbent systems to alleviate pressure buildup and volume expansion of kimchi packages

Kimchi, a lactic acid fermented vegetable dish, is usually packaged without pasteurisation and produces a lot of carbon dioxide inside its package during storage and marketing. In order to develop a kimchi packaging system with controlled pressure and volume, various chemical CO 2 absorbents were compared for use in the packages. Na 2CO 3 was shown to have a good potential for absorbing CO 2 in kimchi packages under conditions with an adequate water supply. The properties of Na 2CO 3 as a CO 2 absorber were characterised and then used for designing a new CO 2 absorbent system for kimchi packages. The water vapour and CO 2 transmission rates of the sachet and plastic sheet containing Na 2CO 3 were used as a useful design variable to control the CO 2 absorption rate. Na 2CO 3 was also combined with zeolite in order to control the CO 2 absorption rate and maintain equilibrium conditions. When the combined CO 2 absorbing material was fabricated into a sachet or expanded polystyrene sheet and then attached inside the kimchi package, the reduced pressure buildup and volume expansion were attained with proper levels of CO 2 partial pressure.

Gravure‐printed colour indicators for monitoring Kimchi fermentation as a novel intelligent packaging

AbstractGravure‐printed colour indicators on common nylon/polyethylene (Ny/PE) films were newly developed for kimchi (fermented vegetable products in Korea) packaging to examine the degree of fermentation of such products non‐destructively during distribution and sale. A printing ink consisting of Ca(OH)2 as a CO2 absorbent, bromocresol purple (BP) or methyl red (MR) as a chemical dye, and a mixture of polyurethane and polyester dissolved in organic solvents as a binding medium, was applied on Ny films by the gravure process and then laminated with PE films to form the printed indicator. During storage at 0, 10, 20°C, kimchi fermentation was assessed for titratable acidity (TA), and the colour of the indicators was determined as Hunter values and expressed as total colour difference (TCD). Although TCD value of the BP type indicator was slightly less than that of the MR type, colour changes in both the types of indicator correlated well to TA values of kimchi. The results suggest that gravure‐printed colour indicators have great potential as an intelligent packaging system for monitoring the ripeness of commercial kimchi products. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Use of color indicators as an active packaging system for evaluating kimchi fermentation

Color indicators for kimchi (fermented vegetable products in Korea) packaging have been newly developed to evaluate the degree of fermentation of kimchi products non-destructively during storage and distribution. Kimchi fermentation was assessed for titratable acidity (TA), and color changes of the indicators were measured and expressed as Hunter values as well as total color difference (TCD). TCD values of bromocresol purple (BP) type indicator (containing BP as a chemical dye) ranged 27–33 and were much more than those of methyl red (MR) type (containing MR). A kinetic approach was used to correlate the response of the indicators to the changes in kimchi fermentation. Color changes of both BP and MR type indicators correlated well with TA values of kimchi. The present results suggest that color indicators be applicable to kimchi products as an active packaging system for monitoring their ripeness.

Development of Color Indicators for Kimchi Packaging

ABSTRACTColor indicators for kimchi(fermented vegetable product) packaging were developed to monitor the quality of such commercial products during storage and distribution. Kimchiwas packed in a polypropylene (PP) tray with nylon/cast polypropylene (Ny/CPP) lid. A color indicator film consisting of PP resin, Ca(OH)2 as a CO2 absorbent and bromocresol purple or methyl red was attached to the lid. During fermentation at 0,10, and 20°C, kimchi quality was evaluated for pH and titratable acidity (TA), which had been correlated with Hunter color values of the indicators. Regardless of fermentation temperature, the color values correlated well with pH and TA values.

Use of a pinhole to develop an active packaging system for kimchi, a Korean fermented vegetable

A pinhole in a packaging system for kimchi, a Korean lactic acid fermented vegetable, was found to actively modify the headspace gas and improve the quality of the product. The effect of the presence of a pinhole on the headspace atmosphere and microbial flora was investigated in the packaging system and a prototype of this active packaging system was fabricated and tested for its effectiveness in improving quality. The incorporated pinhole eliminated pressure build-up in the package by allowing restricted flow of gas to the atmosphere. O2 and N2 gases in the headspace were flushed out by CO2 gas produced continuously from lactic acid fermentation and this modified atmosphere enhanced the growth of lactic acid bacteria. In particular, the growth of Leuconostoc species, heterofermentative lactic acid bacteria, was promoted by the pinhole. The increased amount of heterofermentative lactic acid bacteria led to a higher accumulation of CO2 in the package and this provided the kimchi with a stronger cool carbonic taste and a desirable flavour. An elaborate design of the pinhole incorporating microporous film and a gas adsorvent could be adopted to improve the kimchi packaging system by preventing leakage of fermentative aroma and possible contamination from outside atmosphere. © 1997 John Wiley & Sons, Ltd.