Research projects  are available with the faculty in the following areas: Food safety and quality, understanding the mode of action of natural antioxidants, fibers, and probiotics. 

Food Science Research Projects 

Supervisor: Dr Said Ajlouni 
Email: said@unimelb.edu.au

Dr Ajlouni’s principle research interests focus on food safety, quality and functionality, with special emphasis on minimally processed foods. Research topics cover various aspects of improving food safety and quality, and understanding the mode of action of natural antioxidants, fibers, and probiotics. 

Prospective research projects

Attachment and biofilm formation by various contaminating microorganisms on various injured fruits and vegetables 

Previous work in our laboratory revealed that minor injury to the shoots of vegetable, significantly (P < 0.05) protected contaminating microorganisms. That phenomenon was termed shoot injury-increased persistence (SIIIP). Unfortunately, there are still substantial gaps and limitations in our knowledge of SIIIP. Among these deficiencies that will be investigated in this proposed project are: 

  • Attachment, growth and biofilms formation of various gram positive and negative contaminating microorganisms on contact surfaces under simulated fruit and vegetables handling conditions. 
  • The mechanism responsible for SIIIP. 
  • The involvement of nutrients from injured plant tissue in SIIIP. 

Risks of foodborne illness from fresh vegetables fertilized with chicken litter 

Poultry litter is used extensively in vegetable production in many parts of Australia as a nutrient supplement and to add organic matter to the soil. Despite much conjecture and debate there is very little scientific data available with respect to food safety issues associated with the use of poultry litter. In this project: the impacts of various farm practices related to litter application on the microbiological safety of the fresh produce will be examined. 

Salmonella –free eggs 

Salmonella is a major microorganism of human health concern. It is quite often associated with eggs, poultry and their products. Salmonella can be introduced into laying flocks via feed, water, the laying environment and personnel. Soiled, visually dirty, and cross-contaminated eggs during food preparation, and allowing foods containing raw egg to be held at temperatures that would permit the growth of Salmonella are main factors contributing to salmonellosis. The consumption of uncooked or lightly cooked sauces and desserts containing raw eggs could be a risk factor in food outbreaks. 

This project will examine the possible production of Salmonella-free shell eggs using ozonation with and without sonication. 

Microbiological safety and nutritional value of foods during modified atmosphere packing 

Modified atmosphere packing has been proven to retard microbial spoilage, thereby extending the shelf life of fresh produces. However, using a modified atmosphere to stop the growth of spoilage microorganisms does not necessary affect the growth of pathogenic bacteria. 

Fruits and vegetables contain significant amounts of antioxidants such as,  &  carotene, lycopene, lutein, vitamins A, C & E and the mineral selenium. Research and nutritional studies continue to reveal that consumption of dietary antioxidants reduces the risk of cancer. 

However, the effect of handling, processing, and storage (normal and modified atmosphere) on the availability of the antioxidants in fresh produce during storage if not fully understood. 

This project will examine the possible growth and increment in the population of pathogenic bacteria during the extended storage of fresh produce, and the relationship between microbial population and the availability of antioxidants. 

Impacts of biofilms on safety and quality of foods 

A deeper understanding of the microbial ecology of biofilms during food processing is very essential step toward establishing intervention strategies to effectively control microbial biofilms in the food processing industry. Many microorganisms can adhere to solid surfaces and surround themselves with a protective matrix of polysaccharides. Biofilm-associated microorganisms undergo a variety of changes such as reduction in cell size, acquisition of a viable but non-culturable (VBNC) form of life and resistance to antimicrobial agents. It is increasingly suspected that biofilms play an important role in food contamination during processing and packaging. 

Research projects to study biofilm formation under different food (meat, fresh produce, and dairy products) processing environments and developments of appropriate techniques and barriers to stop biofilms formation will be investigated. 

Dietary lycopene and anthocyanin in fresh and processed tomatoes 

Lycopene is a carotenoid, while anthocyanin is a flavonoid, and both are found predominantly in tomatoes, and form the pigment responsible for the red and blue colors. Antioxidants content varies widely among tomato varieties and increases dramatically during ripening. The concentration of lycopene in ripe fruits of the common variety lycopersicon esculentum ranges between 31-77 g/g fresh weight. However, the recent development and production of blue tomatoes which have good color and appearance from a consumer prospective have raised the question about the quantity and availability of lycopene and anthocyanin in these cultivars. 

A previous investigation in our laboratory revealed that the average lycopene content in ripe hydroponic (Pyramid) and non-hydroponic tomatoes was 36g/g fresh weight (fw). 

Changes in lycopene and anthocyanin and their availability during storing, handling, and processing are not well understood, and will be further investigated. 

Development of freeze dried yoghurt 

Yoghurt stands alone for its texture, taste, nutritional value, variety, versatility and protective health properties. It is a unique blend of nutritious milk and beneficial bacterial cultures yielding a healthy and tasty food that is consumed universally and by all ages. Some starter cultures used in modern yoghurt production enhance flavor and aroma while others, such as Lactobacillus acidophillus and Bifidobacterium are included for their therapeutic effects on human health. 

The proposed project will investigate the possible production of instant yoghurt fortified with Bifidbacteria using freeze drying techniques. 

Antioxidants in popcorn as compared to chocolate and some fruits and vegetables 

Popcorn is the only snack that is 100% unprocessed whole grain. It is considered a perfect snack food, and can enrich human diet with a good source of whole grain. However, methods of popcorn preparation and serving may have significant impact on its polyphenol contents and nutrients bioavailability. 

This project will examine the impact of cooking (stove Vs microwave) and added ingredients (oil, fat and salt) on popcorn antioxidant contents and nutritional value. 

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