Research Projects in 2011-2012

COOL-MEAT: A Novel Method for Improving the Vacuum Cooling of Cooked Meats (Postdoc)

L. Drummond and Da-Wen Sun

Sponsors: EU 7^th Framework

Strict EU guidelines demand that cooked meat joints including ham, turkey, chicken, pork and beef be cooled within rigid time limits after cooking. Conventional cooling methods depend on heat conduction to cool the inside of the joints, but the relatively low thermal conductivity of meat, coupled with restrictions on the minimum temperature of the cooling medium (to avoid surface freezing) makes it difficult to increase the rate of cooling significantly. Vacuum cooling is a rapid evaporative cooling technique for moist and porous products that offers many advantages over conventional cooling methods. However it leads to substantial weight loss and as a consequence, vacuum cooked meats are slightly less tender, drier and darker. A novel combined cook–cool technique known as immersion vacuum cooling (IVC), whereby the vacuum cooling of cooked meat is performed together with some of its cooking solution, was explored for its potential use for rapid cooling of water-cooked meat joints. Reduced yield losses and improved quality for cooked pork ham and large cooked beef joints have been reported. This project will build on this past research in order to apply and validate the technique in industry and to plan for the post-project commercial scale up of the IVC system and its subsequent market entry, whereby its uptake will improve the competitiveness of European Small and Medium Enterprises (SMEs) from the cooked meats sector.

---

A Novel Method for Improving the Vacuum Cooling of Cooked Meats (COOL-MEAT) (Postdoc)

Z. Zhang and Da-Wen Sun

Sponsors: EU 7^th Framework

In order to minimise the growth of pathogens in the cooked meat industry, strict EU guidelines demand that cooked meat joints must be cooled within tight time limits after cooking. Conventional cooling methods depend on heat conduction to cool the inside of the joints, but the relatively low thermal conductivity of meat coupled with the necessity to maintain a temperature of the cooling medium above 2ºC (to avoid surface freezing) makes it difficult to increase the rate of cooling significantly. Vacuum cooling is a rapid evaporative cooling technique for moist and porous products that offers many advantages over conventional cooling methods, such as short processing time, extension of product shelf life and improvement of product quality, safety and nutritional content. However it leads to considerable weight loss and, due to high moisture loss, vacuum cooked meats are slightly less tender, drier and darker. There is a need to provide cooked meat producers with an effective rapid cooling method. A novel technique known as immersion vacuum cooling (IVC) has recently been researched, whereby the vacuum cooling of cooked meat together with some of its cooking solution was explored for its potential use for rapid cooling of water-cooked meat joints. Reduced yield losses and improved quality for cooked pork ham have been reported. This project will build on this past research in order to apply and validate the technique in industry and to plan for the post-project commercial scale up of the IVC system and its subsequent market entry, whereby its uptake will improve the competitiveness of European SMEs from the cooked meats industry.

---

Rapid, Objective and Quantitative Determination of Meat Quality by Non-Destructive and Non-Contact Hyperspectral Imaging System (Postdoc)

G. El Masry and Da-Wen Sun

Sponsors: EU Food Institutional Research Measure / Department of Agriculture, Fisheries and Food, Dublin

Hyperspectral imaging or imaging spectroscopy is a new technique that combines both imaging and spectroscopy techniques to acquire spatial and spectral information from an object. The three-dimensional image obtained from hyperspectral imaging is called “hypercube”. While the two spatial dimensions (x and y) describe the spatial features of the objects, the third dimension (λ) provides the spectral information for each pixel on the hyperspectral image cube. Because of this combined feature of imaging and spectroscopy, hyperspectral imaging can enhance the capability of detecting some chemical constituents in an object as well as their spatial distributions. Therefore, this project aims to develop a novel hyperspectral imaging system for quantitative and objective determination of meat quality. In order to do this, meat muscle of different attributes will be investigated in visible and near infrared (VIS/NIR) ranges of spectrum and the most critical image attributes relevant to meat quality (palatability) such as protein, water and fat content will be investigated. Measurements based on traditional instruments and sensory analysis will be also carried out to test, train and validate the hyperspectral imaging system, leading to the establishment of reliable meat quality predictors.

---

Novel Method for Assisting and Accelerating the Aging Process of Wine (ULTRAFINEWINE) (Postdoc)

J. F. García Martín and Da-Wen Sun

Sponsors: EU 7^th Framework

Wine producers are constantly striving to achieve a stable product with an extended period of peak taste and bouquet. Naturally aged wine tends to be milder tasting and smoother to drink than non-aged wine. Research to date has revealed that the aging process can be enhanced with by the application of high pressures and temperatures over time. This project will build on past research that has demonstrated promising results for the application of temperature and pressure by ultrasonic radiation which can alter the interaction of wine ingredients to obtain chemical changes in the wine resembling many years of natural ageing. A prototype ultrasound device will be designed, built and integrated into existing wine fermentation vats in order to validate its usefulness at industrial scale for the production of homogenous wines with an extended shelf-life in very short periods of time compared to natural ageing.

---

Novel Method for Assisting and Accelerating the Aging Process of Wine (ULTRAFINEWINE) (Postdoc)

Q.-A. Zhang and Da-Wen Sun

Sponsors: EU 7^th Framework

The ageing process is an important step for producing high quality wine products. Naturally aged wine tends to be milder tasting, smoother to drink and have a higher metabolism than non-aged wine. The traditional ageing technology is based on the storage of wine in oak barrels or bottles, while there are some disadvantages about it including time-consuming, cost and space of storing barrels or bottles of wine, and possible contaminations. This project is built on past research that has demonstrated promising results for the application of temperature and pressure by ultrasonic radiation which can alter the interaction of wine ingredients to obtain chemical changes in the wine resembling many years of natural ageing. A prototype ultrasound device will be designed, built and integrated into existing wine fermentation vats in order to validate its usefulness at industrial scale for the production of homogenous wines with an extended shelf-life in very short periods of time compared to natural ageing.

---

Prediction of Eating Qualities of Salmon Fillet from Colour, Marbling and Surface Texture Features Using Hyperspectral Imaging Technique (Postdoc)

D. Wu and Da-Wen Sun

Sponsors: Irish Research Council for Science, Engineering and Technology

The development of rapid and accurate quality and safety inspection systems with the function of visualizing attribute distribution are important for the Irish salmon industry to ensure the safe production of salmon products during processing operations and the labeling of products correctly related to the quality, safety, authenticity and compliance. With the integration of the main advantages of spectroscopy and imaging, hyperspectral imaging technique can simultaneously acquire spectral and spatial information in one system, leading to its capability of measuring both external physical and morphological characteristics and internal quality attributes from a salmon fillet. In order to do this, a reliable hyperspectral imaging system with quantitative models will be trained, established, and validated for rapid and non-invasive measurement of quality and safety attributes of salmon fillets based on the most critical image features extracted from visible and invisible (near infrared) hyperspectral images of salmon fillets and their reference attribute values, which will be measured by using traditional instruments and sensory analysis.

---

Spectroscopic Technique for Food Authentication by Detecting Adulteration and Microbial Spoilage (Visiting Scientist)

N. El Sayed Morsy and Da-Wen Sun

Sponsors: University College Dublin

The determination of food authenticity and the detection of adulteration are major issues in the food industry, and are attracting an increasing amount of attention. The intensification of agriculture and urbanisation over the last decades has created a major concern of many consumers about the authenticity and the safe of their food. Proper product description is of crucial importance in ensuring fair trading practices and enabling consumers to make liable choices. Among other motives, the high commercial value of food products of high consumer popularity leads to an expressed need for fast and reliable methods to recognise essential information about food products and to ensure the authenticity of these products. Food authenticity issues in the form of adulteration and improper description have been around for a long time and probably for as long as food has been offered for sale. Adulteration of food can be in the form of complete or partial omission or abstraction of valuable constituents; whole or partial substitution of food component with an undeclared alternative (usually cheaper); concealment of damage or inferior foodstuffs and/or adulteration by adding undeclared substances or material to increase product bulk or weight or make the product appear better value than it is. With food products major authenticity issues concern the substitution of high value raw materials with cheaper materials. On the other hand, with increased expectations for agricultural products of high quality and safety standards, the need for accurate, fast and objective quality determination of food characteristics continues to grow. Although there are some traditional methods for discovering and detecting wide range and low levels of food adulteration, spectroscopic methods are attractive options due to the speed of analysis and minimal sample preparation. Therefore, this project aims to investigate the feasibility of NIR spectroscopy for quality monitoring and authentication in minced meat to discover adulteration by offal, liver, kidney, tongue and pork as well as predicting the microbial load in minced meat due to abuse storage.

---

Quality Classification and High-Speed Assessment of Fat, Moisture and Protein Content Distribution in Spanish Cooked Ham Using NIR Hyperspectral Imaging System (Visiting Scientist)

P. Talens-Oliag and Da-Wen Sun

Sponsors: University College Dublin

The objective of this study is to investigate the potential of hyperspectral imaging in the NIR spectral region of 900–1700 nm for the classification and characterization of Spanish cooked hams. Three different qualities of Spanish cooked ham named according to the Spanish legislation as: Category I (extra quality), Category II (normal quality) and cold cut ham (low quality), are being employed in these studies. Total protein content, sarcoplasmic and myofibrillar protein amounts, and moisture and fat content, are being measured in all hams. Hyperspectral images are being acquired for ham slices originated from each quality grade, and a subsampling approach for relating spectral and chemical features will be applied.

---

Prediction of Pork Sensory Attributes Using NIR Hyperspectral Imaging Technique (PhD)

D. Barbin, G. ElMasry, Da-Wen Sun and P. Allen

Sponsors: Food Institutional Research Measure (FIRM) Strategic Research Initiative / Department of Agriculture, Fisheries and Food

In this study, a hyperspectral imaging based technique was investigated for objective determination of pork sensory attributes. Near-infrared hyperspectral images (900-1700 nm) were obtained for pork samples from the longissimus dorsi muscle, and representative spectral information was extracted from the loin eye area. Spectral information was related to sensory characteristics by partial least-squares regression (PLSR) models. The results showed that pork meat could be discriminated into tender and tough categories with a coefficient of determination (R²) of 0.78. Results indicated the potential use of NIR hyperspectral technique for rapid assessment of pork quality.

---

NIR Hyperspectral Imaging and Partial Least Squares for the Prediction of pH, Colour and Drip Loss of Lamb Muscles (PhD)

M. Kamruzzaman, G. ElMasry, Da-Wen Sun and P. Allen

Sponsors: Food Institutional Research Measure (FIRM) Strategic Research Initiative/ Department of Agriculture, Fisheries and Food

The potential of near-infrared (NIR) hyperspectral imaging was evaluated for the prediction of pH, colour (L* value) and drip loss of different lamb muscles. Hyperspectral images of lamb muscles were obtained using a pushbroom NIR hyperspectral imaging system in the spectral range of 900-1700 nm. Muscles from semitendinosus (ST), semimembranosus (SM), Longissimus dorsi (LD) of Suffolk, Telex, Blackface and Charollais breeds were used for the study. Partial least squares regression (PLSR) models were developed to build a relationship between spectral data and the various quality attributes measured. The models performed well for predicting colour, pH and drip loss with the coefficient of determinations (R2) of 0.92 0.58 and 0.66, respectively. The study demonstrated that NIR hyperspectral imaging can be used for rapid evaluation quality attributes of lamb.

---

Active Control of Nucleation and Ice Crystal Size in Agar Gels by Ultrasound Irradiation: Process Evaluation and Microstructural Analysis (PhD)

H. Kiani, Z. Zhang, A. Delgado and Da-Wen Sun

Sponsors: University of Tehran / The Iranian Ministry of Science

Nucleation of ice during freezing is an important phenomenon affecting the probability distribution of the ice crystal size and crystal growth rate. Power ultrasound has been proven to be useful in promoting the nucleation of ice in water-based solutions and different theories have been proposed to describe the mechanism of this phenomenon. In the present work, the use of ultrasound waves to induce nucleation in agar gel samples was studied. The samples were put into tubing vials and were frozen in an ethylene glycol - water mixture (-20 °C) in an ultrasonic bath system. Ultrasound (25 kHz, 0.45 W cm^-1) was applied continuously for 3 s at different sample’s temperatures. Results indicated that ultrasound irradiation at different temperatures was able to initiate nucleation in agar gel samples after a short delay. Microstructure evaluation of the samples revealed that the size distribution of ice crystals was affected by ultrasound induced nucleation temperature. Decreasing the nucleation temperature resulted in smaller ice crystals created in the sample. In conclusion, the use of ultrasound as a means to control the crystallization process offers promising application in food freezing but further investigations to understand the mechanisms is required before it can be adopted, especially for solid foods.

---

Spectral Techniques for Detecting Microbial Spoilages and Bacterial Pathogens in Food (PhD)

Y. Z. Feng, G. ElMasry and Da-Wen Sun

Sponsors: CSC-UCD Scholarship Scheme

Detection of bacterial pathogens and spoilage organisms is critical in food surveillance. Several methods are available. Culture and colony counting method and polymerase chain reaction are powerful but strongly restricted by their intrinsic drawbacks. More promising vibration spectroscopy techniques have been applied in the identification of microbes, but efforts are still needed to establish robust models for industrial application. Moreover, as an emerging method, hyperspectral imaging is also suggested a worthy of further study.

---

Cooling of Cooked Carrot Cubes of Different Sizes with Three Cooling Methods (PhD)

C. H. Feng, Z. Zhang, L. Drummond and Da-Wen Sun

Sponsors: EU 7th Framework Programme / CSC-UCD Scholarship Scheme

Three different cooling methods: air blast cooling, immersion cooling, and vacuum cooling were evaluated based on their cooling losses and cooling times for different sizes of cooked carrot cubes. For the same sizes of samples, results revealed the shortest cooling time, however, with the highest cooling loss were obtained when carrots cubes were cooled using vacuum cooling, compared to the other cooling methods. For the same cooling method, different sample sizes exerted a small impact on the cooling loss while shorter cooling time was obtained when the size was smaller. It was concluded that, irrespective of the sizes of carrot cube, vacuum cooling was the most efficient cooling method in comparison with the other cooling methods but it caused the highest cooling loss; on another hand, the impact of a larger size on cooling time for vacuum cooling was much smaller than for the other cooling methods, even though a larger size resulted in longer vacuum cooling time.

---

Innovative Wine Ageing Technologies for Producing Fine Wines During a Short Ageing Period (PhD)

Y. Tao, J. F. García and Da-Wen Sun

Sponsors: EU 7th Framework Programme / UCD-CSC Scholarship Scheme

Wine ageing is an important process to produce high-quality wines. Traditionally, wines are aged in oak barrel ageing systems. However, due to the drawbacks of the traditional ageing technology, including time consumption, high cost, etc, innovative ageing technologies have been developed. The technologies introduced in this paper can produce fine wines during a short ageing period. Therefore, they are regarded to greatly benefit the modern winemaking industry.

---

Freezing Process Effects on Pork Quality Features (MEngSc2)

S. Chao, D. Barbin and Da-Wen Sun

Sponsors: University College Dublin

The effects of frozen storage on pork quality properties will be investigated. Thawing loss, pH and colour measurements will be performed to determine differences between fresh and frozen-thawed pork. Spectral information will be used to distinguish differences between fresh and frozen-thawed meat. The purpose of this study is to evaluate how the freezing process affects pork quality. The results will be used to investigate how damage in the meat structure caused by freeze-thawing cycles can be identified through physical tests.

---

Prediction of Fat and Moisture Content in Pork Using NIR Hyperspectral Imaging Technique (PhD)

D. Barbin, G. ElMasry, Da-Wen Sun and P. Allen

Sponsors: Food Institutional Research Measure (FIRM) Strategic Research Initiative / Department of Agriculture, Fisheries and Food

Hyperspectral imaging based technique was investigated for objective determination of moisture and fat contents in pork. Near-infrared (NIR) hyperspectral images (900-1700 nm) were acquired for both intact and minced pork samples and representative spectra were extracted by automatic segmentation. Moisture and fat contents were determined by traditional methods and then related with the spectral information by partial least-squares regression (PLSR) models. The coefficient of determination obtained indicated that the NIR spectral range had an excellent ability to predict the content of moisture (R²_cv = 0.86) and fat (R²_cv = 0.95) in pork. Results indicated the potential use of NIR hyperspectral imaging technique for rapid assessment of pork composition.

---

NIR Prediction of Chemical Composition in Lamb Meat Using NIR Hyperspectral Imaging (PhD)

M. Kamruzzaman, G. ElMasry, Da-Wen Sun and P. Allen

Sponsors: Food Institutional Research Measure (FIRM) Strategic Research Initiative / Department of Agriculture, Fisheries and Food

Emerging concerns about safety and quality and increased demands by the consumers, legislators and competition have promoted the meat industry migrating from its invasive testing methods yet practised in the meat industry to newer, non-destructive techniques. The main goal of this study was to investigate the potential of hyperspectral imaging in the near infrared (NIR) range of 900-1700 nm for non-destructive prediction of chemical composition in lamb meat. Hyperspectral images were acquired for lamb samples originated from different breeds and different muscles. The mean spectra of the samples were extracted from the hyperspectral images and multivariate calibration models were built by using partial least squares (PLS) regression for predicting water, fat and protein contents. This study clearly illustrated that NIR hyperspectral imaging in tandem with PLSR modelling can be used for the non-destructive prediction of chemical compositions in lamb meat.

---

Ultrasound-Assisted Freezing of Probiotic Bacteria: The Freezing Process and Cell Viability

H. Kiani, Z. Zhang, M. Naciri, M. Al-Rubeai and Da-Wen Sun

Sponsors: University of Tehran / The Iranian Ministry of Science

Maintaining highly viable probiotic lactic acid bacteria cells in frozen products is quite important. Power ultrasound has been considered recently as a novel technique for improving the freezing process. In this paper, the effects of power ultrasound on the freezing process and the viability of Lactobacillus plantarumsubsp. plantarumafter freezing were assessed. The bacteria were grown in MRS broth and transferred into 1.2 ml tubing vials with or without DMSO. Freezing was performed in an ultrasonic bath system (25 kHz). Ultrasound irradiation (3 s, 0.25 W cm^-2) at different supercooled temperatures caused nucleation to occur close to the irradiation temperature. Lower nucleation temperatures resulted in a shorter phase change stage and reduced cell viability. Ultrasound-assisted irradiation at higher temperatures (-2 and -4 ⁰C), on the other hand, increased the viability of the cells significantly. Ultrasound irradiation during the phase change stage of the freezing process (4 min) led to a further increase in the viability of the cells while reducing the freezing time. The higher mass transfer rate of water molecules achieved by ultrasound irradiation might have caused the improved viability and faster freezing process. Our results revealed that ultrasound irradiation during the nucleation stage or phase change step of the freezing process holds promise as a tool to ensure the higher viability of frozen suspended cells.

---

Effects of Immersion Vacuum Cooling of Sausages with Different Water Levels (PhD)

C. Feng, Z. Zhang, L. Drummond and Da-Wen Sun

Sponsors: EU 7^th Framework Programme / CSC-UCD Scholarship Scheme

Three different water levels (distance from the top of sausage to water surface) were employed during immersion vacuum cooling of sausage, namely: high (HWL: 17 cm), middle (MWL: 7 cm) and low water level (LWL: 0.8 cm). Results revealed that the average final core sausage temperature achieved at HWL was just about 8^oC, while sausages cooled at MWL and LWL reached approximately 6^oC and 4^oC, respectively. This may be due to the poor heat transfer from water bottom to surface and between the sausage and water at bottom in high and middle water level. The average cooling time (to 8^oC) was found to be significantly different (P<0.01) between the three water levels: 47.32, 33.97 and 24.39 min for HWL, MWL and LWL, respectively. Total cooling times for MWL (to 6^oC) and LWL (to 4^oC) were 38.52 and 34.06 min, respectively. In terms of mass losses, TPA and moisture analysis, they were not statistically significantly affected (P>0.05) by the water levels. It could be concluded that IVC of sausages using LWL accomplishes the shortest cooling time, achieves the necessary final temperature and yields a product of acceptable quality.

---

Modelling Food Processes Enhanced By Ultrasound (PhD)

Y. Tao and Da-Wen Sun

Sponsors: EU 7^th Framework Programme / CSC-UCD Scholarship Scheme

In food processing, the applications of ultrasound can be divided into two categories, namely replacing traditional technologies and assisting traditional technologies. In the latter case, the processing efficiency is enhanced and the disadvantages of traditional technologies during processing are improved. Among the processes enhanced by ultrasound, non-parametric simulative models can be employed to model the extraction and oxidation processes. With regard to ultrasound-enhanced freezing, thawing, brining and drying processes, it is better to use the models which can express the physical meaning of these processes. In the meantime, several empirical models can be considered to model the drying process in the presence of ultrasound.

---

Determination of Enterobacteriaceae in Chicken Fillets Using NIR Hyperspectral Imaging and Multivariate Data Analysis (PhD)

Y. Z. Feng and Da-Wen Sun

Sponsors: CSC-UCD Scholarship Scheme

Hyperspectral imaging was investigated for fast and direct determination of Enterobacteriaceae loads on chicken fillets. The spectral range of 930-1450 nm was utilized to establish full wavelength partial least squares regression (PLSR) models. The good performance, i.e., coefficients of determination R² ≥ 0.82 and root mean squared errors (RMSEs) ≤ 0.47 log10 CFU g^-1, suggested great precision and stability of the PLSR model. Simplified PLSR models were also developed by utilizing only three wavelengths (930, 1121 and 1345 nm) selected from the PLS regression coefficients (BW) plot produced from the optimal full wavelength model, and the obtained R² were as high as 0.89, 0.86 and 0.87 with corresponding RMSEs of 0.33, 0.40 and 0.45 log10 CFU g^-1 for calibration, cross validation and prediction, respectively. It was demonstrated that hyperspectral imaging is a potential tool for determining food sanitation and detecting bacterial pathogens on food matrix without using complicated laboratory regimes. In the future, multispectral imaging systems can be developed to conduct on-line detection of Enterobacteriaceae in the food industry.

---

Application of Hyperspectral Imaging Technique for Non-Destructive pH Prediction in Salmon Fillets (PhD)

H. J. He, D. Wu and Da-Wen Sun

Sponsors: CSC-UCD Scholarship Scheme

Hyperspectral imaging (HSI) techniques in the wavelength of 400−1000 nm was applied for rapid and non-destructive measurement of pH value in salmon fillets. Spectral signatures were extracted and analyzed by partial least-squares regression (PLSR) to correlate spectral data of fillet samples with its pH values estimated by using a pH meter. Important wavelengths were selected by analyzing loading weights of PLSR model to build a simple PLSR model. The new PLSR model led to a correlation coefficient (RCV) of 0.852 and root-mean-square error estimated by cross-validation (RMSECV) of 0.050. The results showed that hyperspectral imaging technique was suitable for rapid and non-destructive assessment of pH value in salmon fillets.

---

Non-destructive Evaluation of Apple Quality by Hyperspectral Imaging (MEngSc2)

N. Udayakumar, G. ElMasry and Da-Wen Sun

Sponsors:University College Dublin

A hyperspectral NIR imaging system was tested to evaluate the apple quality nondestructively. The study was carried out in the near infra-red (NIR) region (900- 1700 nm). Hyperspectral images were acquired for apple fruits and their spectral data were registered and analyzed. The acquired images were processed using the image processing software ENVI. Results indicated that the hyperspectral technique can be applied for the fast and non-destructive assessment of apply quality evaluation.

---

Investigation of Effect of Pressure Reduction Rate on the Immersion Vacuum Cooling of Cooked Hams (MEngSc2).

Y. Jia, Z. Zhang and Da-Wen Sun

Sponsors: University College Dublin

Immersion vacuum cooling is a good method to compensate the mass loss of vacuum cooling. In order to further understand immersion vacuum cooling, two pressure reduction rates, namely, 60 mbar/min and 100 mbar/min, were compared for their effect on cooling time, weight loss and quality of large cooked ham product during immersion vacuum cooling. Samples were cooled from a core temperature of 72 ^oC to 4 ^oC in a laboratory scale vacuum cooler. The first experiment results indicated that cooling time was shorter for a pressure reduction rate 100 mbar/min. But more replications need to be conducted for statistical significant results.