Strategies and Technology to Determine Chicken Freshness

Strategies and Technology to Determine Chicken Freshness 2.0Â  INTRODUCTION Recently, there have been various inventions of sensors to detect the freshness of food. A chemical sensor means that a tool that convert chemical information into an analytically useful signal. The device acts as an analyzer (Hulanicki et al, 1991). Smart or intelligent packaging has been the result of using such sensors into the food packaging technology. Smart packaging uses chemical or biosensor to observe the quality and safety of food from the producers and relay the outcome to the consumers. Time-temperature indicators, ripeness indicators, chemical sensors, biosensors and radio frequency identification are some of the examples of components in smart packaging (Kuswandi et al, 2011). 2.1Â  Chemical Sensor in Determining Chicken Cuts Freshness Chicken is a highly perishable food, as it usually deteriorates within a week of slaughtering, even when it is put in storage chiller systems. Chicken spoilage is mainly due to microorganisms (Kuswandi et al, 2013). Microorganisms in broiler chicken are heterogenous. The common microorganisms in aerobically stored, chilled poultry meats are Flavobacteria, Shewanella putrefaciens, Acinetobacter spp., Corynebacteria spp., Moraxella spp. and fluorescent pseudomonas (Amaut-Rollier et al, 1999). Biogenic amines (BAs) are generated by the growth of decarboxylase-positive microorganisms under favourable conditions to enzyme activity. Many Enterobacteriaceae, Pseudomonas spp. and certain lactobacilli, enterococci and staphylococci are active in the formation of Bas. The amount of amines formed depends abundantly on the type of microorganisms present. The formation of amines, including BAs is primarily a product of the enzymic decarboxylation of specific amino acid due to microbial enzyme activity (Kuswandi et al, 2013). The amino acids can also suffer oxidative deamination, decarbozylation and desulfurization, resulting in gases such as NH3, CO2, and H2S. Carbon dioxide (CO2) is generally known to be produced during microbial growth. (Rukchon et al, 2014) Quantifying chemical changes could provide information on the degree of spoilage. A number of indicators have been proposed to analyse the quality of meat, including BAs, volatile bases, nucleotide breakdown products, volatile acidity and CO2. Thus, these compounds can be taken as quality indicators of chicken freshness during storage (Rukchon et al, 2014). 2.2Â  Problem Statement Increasing of production of poultry meat and products are significant throughout the world in the last decade. Chicken and poultry products are famous because of their specific sensory attributes and the tendency of the public to consider white meat are healthier than red (Balamatsia et al, 2005). Nowadays, demands for the freshness and safety of food products by the consumers are increasing continuously (Kuswandi et al, 2013). However, spoilage of chicken and poultry products has become a burden to the producers plus it can bring a health hazard to the consumers, since poultry meat may contain pathogenic microorganisms (Economou et al, 2009). However, with the invention of smart packaging, which can observe the quality and safety of food and relay the result to the consumers. The sensors used in the packaging come with variety of functions, such as monitoring the freshness, pathogens, leakage, carbon dioxide, oxygen, pH, time and temperature. The technology is beyond the existing standard technologies, which are control of weight, volume, colour, appearance and etcetera (Kuswandi et al, 2011). Colour changes of pH dyes such as bromothymol blue, bromophenol blue, bromocresol purple, methyl red, bromocresol green, methyl orange, methyl yellow, phenol red can be detect acidic/basic volatile compounds, as they display an irreversible change in colour. These are some of the indicators that can be used to make sensors to detect chicken freshness. The sensors then can be stickered or paste onto the packaging (Rukchon et al, 2014). 2.3Â  Objectives The goal is to satisfy the increasing demands of customers, to be able to produce fresh goods, or at least providing scientific evidence informing the customers of the condition of the product, and not based on oral evidence only, as the seller or producer can just fabricate the truth. The objectives of this study are: To investigate the relationship between the numbers of microorganisms and level of spoilage To develop an indicator to monitor the freshness of chicken 3.0 LITERATURE REVIEW 3.1Â  Smart Packaging Smart packaging are packaging that can do more than traditional packaging, in terms of storing, protecting and providing information about the product (Kerry and Butler, 2008). Smart packaging can provide information about the condition (i.e. level of spoilage, freshness of content) of the contents of the pack through colour coding, wireless information, or etcetera. Smart packaging is quite different than active packaging. While active packaging will be activated when it is triggered, smart packaging is more to an indicator of microbial growth, physical shock, leakage or microbial spoilage (Intelligent and Active Packaging Opportunities in Specialty Papers, 2009). Smart packaging can switch on and off according to changing external or internal conditions. Then, it will inform the status of the content to the customers (Butler, 2013). 3.1.1Â  Indicators for Meat Freshness Indicators of freshness can provide direct information from the outcome of chemical changes or microbial growth in food. The production of freshness indicator in meat products depends on the types of product, related spoilage flora, conditions of storage and packaging system (Kerry, 2012). Table 1:Potential indicators in detecting meat freshness (Kerry, 2012) Potential indicators Components to detect Colour-based pH indicators Microbial metabolites Ethanol Fermentative metabolism of lactic acid bacteria Volatile compounds (e.g. dimethylamine, biogenic amines) Muscle-based product decomposition Myoglobin based freshness indicator Hydrogen sulphide, a breakdown product of cysteine Majority of meat freshness indicator are colour change indicator that gives its result according to microbial metabolites that are produced gradually during spoilage (Kerry, 2012). 3.1.2Â  Sensors for Food Pathogens and Contaminants The easiest microbial contamination presence that can be detected indirectly is by measuring changes in gas composition in relation to the microbial growth, by using gas sensor. The increase in CO2 concentration can determines microbial contamination only in packages that do not contain CO2 as a protective gas. The indicators are usually colour changing, that can be based on chromogenic substrates of enzymes produced by the microorganisms, the consumption of certain nutrients or the detection of microorganism itself. One of the examples is the use of nanostructured silk as a platform for biosensors. This silk has quite a lot of advantages, as it is edible and biodegradable, and it can also be integrated within the packaging of products itself. Conducting polymers, one of biosensors can be used to detect the gases released during microbe metabolism. Biosensors are produced by inserting conducting nanoparticles into an insulating matrix, and the change in resistance correlates to the total amount of gas released. These sensors are evolving to detect food borne pathogens through quantification of bacterial cultures (Kuswandi et al, 2011). 3.2Â  Examples of Indicators 3.2.1Â  Methyl Red Methyl red is a pH indicator. The methyl red/cellulose membrane functions as a freshness sensor to detect freshness or spoilage of chicken. It is based on increase of pH, because the amounts of volatile amines that are produced in the package increase gradually making the pH increase as well. Following this, the sensor will change colour from red to yellow as an indicator for spoilage, and it is of course visible to the naked eye. Since the pH of fresh chicken meats is around 5.50 and the pH of spoilt chicken meat is considered above 6.0, the increasing of pH will take place during the deterioration of chicken meats, as the volatile amines are increasing gradually (Kuswandi et al, 2013). Figure 1:Â  The colour changes of methyl red/cellulose membrane versus time of chicken cuts stored at room temperature (Kuswandi et al, 2013) Figure 2:Â  The colour changes of methyl red/cellulose membrane versus time of chicken cuts stored at chiller temperature (Kuswandi et al, 2013) 3.3.2Â  Colorimetric Sensors Array An electronic nose (e-nose) is a tool that can recognise specific components of a smell and examine its chemical makeup to distinguish it. E-nose consists of a system for chemical detection like array of electronic sensors and a system for recognising pattern, such as a neural network (WhatIs.com, 13 November 2014). E-nose system is composed of many non-specific sensors, and an odour stimulus produce characteristic fingerprint from the sensors array. Fingerprints patterns from known odour are then used to make a database, and teach the pattern identifying system so that unknown odours can be recognised and classified (Chen et al, 2014). A low-cost colorimetric sensors array was fabricated, using printing chemically responsive dyes on a C2 reverse silica-gel flat plate, along with a specific colorific fingerprint to identify volatile compounds. AdaBoost-OLDA, a combination of orthogonal linear discriminant analysis (OLDA) and adaptive boosting (AdaBoost) is a classification algorithm that was also proposed to use with the colorimetric sensors (Chen et al, 2014). Figure 3:Â  Schematic diagram of E-nose system based on a colorimetric sensors array (Chen et al, 2014) Total volatile basic nitrogen (TVBN) is one of the best indicators to differentiate between fresh and spoilt poultry. In China, above 15 mg/100 g of TVBN is considered spoilt meat (Chen et al, 2014). Figure 4:Â  Reference measurement results of TVBN content for all samples (Chen et al, 2014) Figure 5:Â  Differences images for fresh chicken sample (a) and spoilt chicken sample (b) (Chen et al, 2014) Figure 5 is the difference of images for the fresh and spoilt samples, by subtracting the initial from the final image. As mentioned earlier, each difference image has its own specific fingerprint. The sensors array which contain the selected metalloporphyrins dyes have responded sensitively to many of volatile organic compounds such as tryptamine, putrescine, cadaverine and other biogenic amines during chicken spoilage. The extra dyes which consist of three pH indicators have responded to hydrogen sulphide and organic acids such as lactic acid. All of the spoilage process can be recorded on the change of chemical responsive dyes (Chen et al, 2014).