Research Projects in 2021-2022

Research on ultrasonic cavitation and its effect on the extraction of hemp protein (PhD)

J F Tang, Da-Wen Sun and B K Tiwari

Sponsors: CSC-UCD Scholarship Scheme

With a series of shortcomings exposed by conventional food processing methods, researchers have employed a green and sustainable innovative processing technology. Compared with traditional methods, cavitation-based processing technology has received extensive attention for its low energy consumption, less pollution, and high product quality. The cavitation phenomenon releases high energy due to the generation and collapse of bubbles, which improves the efficiency of various food processing. In the research, hemp meal was used to study the effect of ultrasonic cavitation on protein extraction. Ultrasonic treatment may effectively improve the extraction rate and yield of hemp protein.

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Antimicrobial effects of airborne acoustic ultrasound and plasma activated water from cold atmospheric plasma jet on biofilms  (PhD)

Y L Zhao, A D Patange, B K Tiwari and Da-Wen Sun

Sponsors: CSC-UCD Scholarship Scheme

Plasma activated water will be generated using an atmospheric cold plasma jet at 30 kV for 5 min. The bacterial suspension will be inoculated into PAW immediately after generation, and the viable counts at different exposure times of 0.5, 1, 3, 5 and 24 h during 4°C storage will be measured to determine the inactivation efficacy. Scanning electron microscopy images of the bacteria will be conducted to examine the structural changes. Physicochemical properties of PAW, including pH, conductivity, oxidation reduction potential (ORP), and concentrations of reactive species including H₂O₂, NO₂^- and NO₃^- will be measured. The results are expected to show the relationship between PAW inactivation efficacy and the applied voltage and exposure time. The susceptibility difference of gram-negative and gram-positive bacteria to PAW. Morphology change will be observed for all bacterial species using a scanning electron microscopy.

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Using hyperspectral imaging to predict texture and rehydration property of beef slices during convective drying and microwave vacuum drying (PhD)

Y Q Ren and Da-Wen Sun

Sponsors: CSC-UCD Scholarship Scheme

The study aims to study the effect of microwave vacuum drying (MVD) and hot air drying (HAD) on moisture content, texture properties and rehydration ability of beef slices samples by hyperspectral imaging (HSI) technique. Using HSI coupled with chemometric methods, calibration prediction models will be established, and the visualisation of moisture content, texture properties and rehydration ability dynamic change could be analysed. Chemometric prediction models based on hyperspectral data and reference analysis data will be established. The moisture content, texture properties and rehydration ability of beef slices with various drying time during hot air drying and microwave vacuum drying are expected to be precisely predicted by the HSI technique. The results demonstrated the HSI system is able to monitor the changes of quality parameters, including moisture content, texture properties, and rehydration ability, of beef slices during microwave vacuum drying and hot air drying.

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Novel post-harvest techniques and their impacts on the valuedadded bioactive compounds of Irish brown seaweed (PhD)

X L Zhu, B K Tiwari and Da-Wen Sun

Sponsors: CSC-UCD Scholarship Scheme

Seaweeds or macroalgae are of extreme relevance in the scientific community as this biomass offer un-parallel opportunities in the discovery of new molecules and compounds including mainly carbohydrates, proteins and lipids, as well as other minor compounds, such as minerals,vitamins and pigments. Most of these compounds have promising potential and demonstrated health benefits in in vivo and/or in vitro models, including antioxidant, antitumor and antibacterial activities. Thus, the interest of several industries in seaweeds has been renewed as not only a source of biomass for basic nutrients, but as promising “multi-factories” able to produce huge amount of compounds with food/feed, pharmaceutical and cosmeceutical applications. This chapter summarizes the current studies exploring the composition of seaweeds, emphasizing the most promising applications and/or biological activities of their main compounds from a food industry perspective; as well as current challenges for their exploitation including the extraction of the compounds and the sustainability issues associated to this growing industry from both an Irish and global perspectives.
Marine algae are regarded as a promising nutrients resource in future as they can be sustainably cultured without land and high investment. These macroalgae are now widely processed into food and beverages, fertilizers and animal feed. Furthermore, bioactive compounds such as polysaccharides and polyphenols in seaweeds have proven to have antibacterial, antiviral and antifungal properties that can be utilized in cosmeceuticals, nutraceuticals and pharmaceuticals.As a key procedure in seaweed production, the post-harvest process not only requires more laboured and energy but also affect the quality of the final product significantly. This paper reviewed all currentpost-harvest processes and technologies of seaweedand addressed potential post-harvest strategies for seaweed production.

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Non-destructive investigation of hydroxymethylfurfural content in honey under different heat treatments (PhD)

G Özdoğan and Da-Wen Sun

Sponsors: YLSY Scholarship Programme, Ministry of National Education, Turkey

Honey is one of the most produced and consumed food substances worldwide, which has a sweet taste, viscous and yellowish appearance, naturally produced by honey bees from floral nectar. It is mainly constituted of 60-85% monosaccharides (glucose and fructose) and 7-10% disaccharides (maltose and sucrose). Besides these, it also contains antioxidants, acids, vitamins, protein, minerals and others. Thermal treatment is a processing procedure in the industry to decrease the tendency of honey crystallization and to destroy contaminated microorganisms. However, this treatment may cause the formation of 5-HMF (IUPAC name, 5-(hydroxymethyl) furan-2-carbaldehyde) which is a cyclic aldehyde. Moreover, it is a toxic, carcinogenic, and mutagenic compound, mainly formed from hexose through the Maillard reaction under high temperatures. Hyperspectral imaging (HSI) is an emerging technology has gained attention as a non-destructive, chemical-free and environment-friendly procedure. Therefore, this study applied to investigate the feasibility of HSI in the near infrared spectral range for the prediction of HMF content in honey under different heat treatments. 7 different brands of honey were obtained from local market. The honey samples were heated in the water bath at 45 °C, 55 °C, 65 °C and 75 °C for 24 h. After heating, hyperspectral images were acquired by a laboratory hyperspectral imaging system. The least-squares support vector machines (LS-SVM) was applied to create prediction models. The highest prediction performance was achieved by standard normal variate (SNV) pre-treated LS-SVM with the coefficient of determination in prediction of 0.894. This study showed that HSI could be a promising technology in honey production for the quality control purpose.

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nondestructive quality evaluation of celery during microwave vacuum drying using spectral and imaging techniques (MEngSc)

C X Zhao, Da-Wen Sun and X H Lin

Sponsors: University College Dublin

Hyperspectral imaging technology provides reliable, efficient and non-destructive analysis of the color change and moisture content. The purpose of this study is to analyze the moisture content and distribution of celery slices during microwave vacuum drying by setting different drying time, so as to analyze and predict the changes of samples during drying. Hyperspectral imaging technology, which combines data analysis with partial least squares regression (PLSR) model, plays an important role in predicting spectral data and moisture distribution. The predicted results can explain the uneven distribution of water in the drying process, and draw the conclusion that there is little difference in the main components of celery before and after drying treatment. It is hoped that this study can provide a suitable method and theoretical basis for moisture analysis and prediction during microwave vacuum drying and dehydration of celery.

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Hyperspectral imaging to measure the moisture content of spinach using microwave vacuum drying (MEngSc)

G Y Dong, Da-Wen Sun and X H Lin

Sponsors: University College Dublin

The moisture content (MC) of spinach samples needs to be determined due to the effect of non-uniform heating temperatures during the microwave vacuum drying (MVD) process. Hyperspectral imaging (HSI) system was used as an emerging non-destructive quality evaluation tool for the measurement of quality indicators such as moisture content in samples. The partial least squares regression (PLSR) model was used to obtain correlations between the spectral data and moisture content. Root square (R²) and the root mean square error (RMSE) was used to evaluate the variability of model. 

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Nondestructive detection of moisture and calorie content in roasted nuts by using terahertz imaging technique (MEngSc)

Z P Hu and Da-Wen Sun

Sponsors: University College Dublin

Moisture and calorie content are two important parameters in roasted nuts, which affect the taste, shelf life and nutritional value of roasted nuts. The project will use a terahertz timedomain spectroscopy (THz-TDS) system combined with chemometrics to quantitatively analyze the moisture and calorie content in roasted nut products. The research will use a variety of algorithms, including partial least squares (PLS) regression, to build predictive models for moisture and calories. The correlation coefficient (R²) and root mean square error (RMSE) will be used to evaluate the accuracy of the prediction model. The project expects to produce several models for predicting the moisture and calorie content of roasted nuts. 

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The quality evaluation of peanuts by using terahertz time domain imaging  (MEngSc)

Q X Li, T Lei and Da-Wen Sun

Sponsors: University College Dublin

Peanuts are one of the most important sources of fats and proteins for humans and are widely grown worldwide. Plumpness (expressed as the percentage of peanut core and shell) is an important index to reflect the quality of peanut seed. The research used a terahertz (THz) time domain imaging system to scan terahertz data for healthy peanuts, incomplete peanuts, and borers. After obtaining terahertz imaging, peanut peel and peanut core were separated, and RGB images were recorded for reference. In this research, a control experiment was set to select the terahertz range in which the absorption coefficients and time domain signals of peanut shell and kernel were significantly different. The dynamic threshold segmentation method was used to establish the fullness model of terahertz image and RGB image. The expected result of the research is that the plumpness of peanut can be measured using terahertz time domain imaging technology to achieve the purpose of quality evaluation of peanut.