Meat tumbling is commonly a process that is practiced in the industry to tenderise and marinate raw meat. It is often done in a vacuum meat tumbler which involves a rotating drum moving the meat pieces around providing outstanding brine distribution inside the meat (Marianski & Mariański, 2010). Vacuum tumbling promotes absorption of brine in meat by opening the meat structure hence allowing the brine solution to penetrate and solubilize the myofibrillar proteins (Alvarado, Owens & Sams, 2001). This promotes better yield, texture and flavour of the meat products. In tumbled meat, the rise in moisture retention is frequently seen after cooking is done and starch may be added in the tumbling process due to its water binding properties. Tumbled meat is also important as it provides an increase in product yield which is one of the important parameters in the industry with regards to economic benefits (Gao et al., 2015).
Current methods performed to evaluate the penetration of brine are through calculating the marinade absorption, light microscopic analysis coupled with Lugol Calleja Staining to detect the presence of starch in meat products (Eliášová, Pospiech, Tremlová, Kubíčková, & Josef Jandásek, 2012). The use of modified starches requires the labelling of E-numbers which may draw consumers off these days. Thus, with natural products increasingly being preferred by consumers, many food manufacturers are moving to native starch options without the addition of chemicals instead of modified starches where they can label it as no additives or preservatives. There is hence a high demand in native starches being used as a marinating ingredient for meat and poultry products. It is a topic worth investigating as understanding the starch penetration in meat, allows cost saving for meat industries by finding the optimum penetration to give the most desired texture and sensory properties of meat. In this study, the method to quantify the extent of starch granule penetration in tumbled chicken fillet is developed with the use of ImageJ and colourimeter with iodine staining and a study is to be carried out to establish suitable tumbling parameters for starch penetration and moisture retention in meat tumbling process. The aim of the study focuses on establishing a method used to quantify the amount of starch granule that has penetrated in the tumbled chicken fillet together with the comparison between the use of different kinds of native starches (Potato, tapioca and rice) in the tumbling process. Aim The aim of the present work is to determine ways to improve the starch penetration in tumbled chicken.
The objectives of the current works are to:
- Optimise the vacuum tumbling process by establishing the optimum processing parameters
- Study the various starch attributes affecting the starch penetration rate in tumbled chicken
- Compare the performance of potato, tapioca and rice starches in tumbled chicken based on the processing conditions established
- Determine the relationship between starch penetration rate and yield/purge
- Develop a method to quantify the amount of starch granule penetration in tumbled chicken with the use of colour and image analysis.
Time may be a possible constraint factor due to the equipment that are available in the lab. Since the cooking will be done solely in Ingredion and the process requires the use of a combi oven, it must be shared among different application teams. Hence this may be an issue as accurate time planning is needed. The vacuum tumbler is a new purchase unit in the Ingredion lab, hence more time is required and taken in consideration in terms of establishing the parameters which may be a constraint as bench work only starts from week 1 of September. Chicken Fillet Sample The source of chicken fillet serves as a constraint as different batches of chicken fillet may be different in terms of the quality of the meat.
To control and minimise the variation, purchase of the chilled chicken fillet must be from the same supermarket outlet. Temperature of the chilled chicken fillet may also be a concern from the point of purchase to the lab storage area. The constraints may be minimised by storing the chilled chicken in a cooler bag with some ice pack to maintain the temperature while transporting. The size of chicken fillet may be an issue as the shape and thickness at which it is cut and place in the tumbler with the brine solution affects the uptake of starch. The problem can hence be reduced by standardising the size and weight of each piece of chicken fillet that is cut if possible.
The research would be done with the use credible sources for instances online scholarly databases such as Science Direct, Ebscohost and ProQuest, scientific journals as well as books and One Search from the SIT library. The search criteria would be based on the year of publication, whether the study is experimental and whether the article or journal is of relevance to the topic. The research would be first started by doing a background search on the topic and the factors that is to be discussed. After literature research is completed, experiment would be carried out the lab to test the processing parameters for the vacuum meat tumbler and starch penetration. The results would later be analysed using colour, image and statistical method to draw the conclusions.
Tumbling temperature is an important factor and should be controlled closely during the meat tumbling process to reduce the amount of heat generated. Increase heat during tumbling may cause the meat protein to denature and reduce uptake and retention (Mckee & Alvarado, 2004). Therefore, preparation of the brine solution (18% extension level) which contains water, salt and starches is to be done using cold water. Since the preferred temperature for tumbling should be below 8oC, other than using cold water to prepare the brine solution, the chicken fillet to be tumbled is also taken out from the chiller right before the tumbling process is about to start and added together with the brine solution in the tumbler. This to prevent any increase in temperature of the chicken affecting the tumbling process. The preparation of the brine solution will also be done according to the weight of the chicken fillet to prevent any unevenness as starch tend to sediment quickly within brines. Tumbling time is also another factor that affects the process. It is stated by Gorsuch (2003) that an increase in tumbling time is seen to have an increase in marination pick-up where more penetration is observed in the tumbled meat (Gorsuch, 2003).
Hence this can be hypothesized that increasing the tumbling time may increase the starch penetration in the tumbled chicken fillet. The time should however be regulated as excessive tumbling time can produce outcomes contrary to those desired, affecting the water holding capacity as well as slice appearance. The tumbling time is set at 30 minutes at 8 rpm under a pressure of -0.7 bar for the first run. After the process is completed, the chicken is steamed at 90oC using a combi oven until its core temperature reaches 80 to 82oC. Cooling is then done for 15 minutes until the chicken reaches 3.3oC. Other proposed tumbling timings which are 45 minutes and 1 hour would also be tested respectively with the same tumbling speed and pressure followed by the steaming and cooling procedures. The optimum tumbling time that obtained the most desired starch penetration and texture of chicken fillet is then established. Attributes of Various Starches Affecting Penetration Rate Different starches have different granule size; hence this may affect the penetration in the chicken during tumbling which make it a significant factor to study. Since the addition of starch also affects the moisture that is retained in the meat, the effect of different starches may also contribute to the moisture retention in chicken during the steaming process which makes it crucial during for sensory properties (Zhang & Barbut, 2005).
Other than the tumbling time, the starch base is also one of the factors that affects the amount that is penetrated in the chicken. The performance of three native starches (rice, tapioca and potato) is to be used in the analysis where they are to be added in the brine solution. Rice starch are waxy starches with less than 5% amylose molecules (Edwards, 2004). It usually gives a much softer texture when used in meat products as it does not gel. Tapioca starches on the other hand have approximately 18 to 23% amylose content and is used in extremely bland meat systems and in instances where a no additive declaration is desired (BeMiller & Whistler, 2009). Potato starch have an extremely high water-binding capacity as compared to other starches. It also has desirable sensory characteristics making it use extensively in the industry for meat application (Tarté, 2009). Potato starches also have a low lipid content in nature, hence application in meat products will not interfere with the natural flavour of meat (Sahoo, Sharma & Chatli, 2011).
Since the claim of clean label is on the rise, the three native starches will be compared to determine which demonstrates the best functional properties when applied to the chicken. Comparison of Various Starches Performance on Processing Condition Established After the desired processing time is established, various starch performances are tested to determine the starch with highest penetration in the chicken fillet. The starch dosage is also increased to investigate whether there is an increase in penetration rate in the tumbled chicken. The amount of starch dosage varying in the brine solution and will be based on dosage percentage of 1%, 1.5% and 2%. Relationship Between Starch Penetration Rate and Yield/Purge The raw weight of the chicken fillet is taken before adding into the tumbler. The weight of chicken after tumbling is also taken to determine the marinade pickup as well as the cooled chicken after steaming. After the cooling process is completed, the chicken will be sent to the blast freezer for rapid lowering the temperature but not to the point of freezing. Each trial of chicken samples is to be stored separately chilled as well as frozen. It is expected to observe a purge in the weight after a week, hence the weight should be measured to confirm and to determine the relationship between starch penetration rate and the yield/purge of the chicken fillet sample.
Quantification of Starch Penetration with Colour and Image Analysis
Colour analysis is to be conducted to quantify the amount of penetration. The stained chicken samples are placed in a blender with addition of water and then strained with a cloth strainer to extract the liquid portion for colourimeter analysis of the amount of starch that has penetrated in the chicken. Image analysis of the amount of starch granule penetration is to be done using ImageJ, an imaging analysis software. The software is frequently used for analysing images where it allows the measurement of area, particle counting, segmentation and measurement of spatial or temporal features of biological elements. An image of the chicken stained with iodine and potassium iodide will be taken and analysed using ImageJ.
A sample of chicken fillet will be taken for image analysis each time after tumbling, after cooling as well as after frozen and chilled storage to study the mechanism of starch penetration. Based on image analysis, the chicken fillets are evaluated for penetration in the chicken fillet based on the maximum penetration depth as well as the percentage of area that is stained with iodine which indicates the presence of starch. The factors are evaluated based on which is the most suitable to be used for chicken meat application. The commencement of the image analysis and colour measurements will be done on week 2 of October after the chicken samples are prepared which can be seen from the Gantt chart as shown in table 1. Statistical Analysis using Design of Experiment (DOE) DOE allows the investigation of the effects of input variables on an output variable at the same time. As the data are collected at each run, DOE is used to identify the process condition and product components that affect the quality and then determine the factor setting that optimize results. The data collected are analysed using Minitab 17 to understand the correlation and significance between each factor.