Water activity might be a guide for selecting food as a representative of perishable or non perishable since the Aw value can show which food can stay longer.

I would certainly consider foods that have been researched in a variety of ways and for which you have all of the information on the components of the food. For example, I have used carrot as a model system for determining the dependency of pH on the diffusion of HCl in foods), this work was built on the digestive work of Kong & Singh (2008, 2009, 2011). Carrot is a great model as it does not swell when soaked in water (having a water content near 90%), and is a common used food with many micronutrients. If you are not considering whole foods, then perhaps dairy products such as yoghurt or cheese (again well studied foods), or alternatively baked goods.

Thank you so much Barbara, Lekhavat, Ghanendra & Amy for sharing your knowledge with me. 

Amy,

I'm considering baked goods for my study. Is normal bread using wheat flour, yeast, sugar, salt, shortening and some water will be a good model to study the effects of phytochemicals to prolong shelf life?

Thanks.

I suggest raw meat and meat products, because they have high moisture content and low shelf life. Adding natural preservatives like phytochemicals, plant essential oils and extracts could be effective for extending shelf life of these products. The other way is, application of phytochemicals in chitosan or CMC film About last 5 years I have tried to focus on antibacterial and antioxidant characteristics of different plant essential oils and extracts In vitro and in food models. If you want any help for this topics, don't hesitate me. 

Aishah,

I think that Majid's suggestion is also very good. You could see if the phytochemicals could reduce oxidation of fat, and reduce rancidity of meat. (Of course, vacuum sealing helps here too). Ideally, I would think you would want slightly processed foods. I think it is great that Majid is keen to establish collaboration with you. I spoke with Jon Palmer, at Massey University (New Zealand),who is a microbiologist. He recommended that if you haven’t done so already, that you start with a standard defined media with known bacterial species (both a gram positive and gram negative bacteria). This would allow you a control that can be easily manipulated (change in pH, etc). He also noted that baked goods may be too dry; all you would be doing is stopping mould from growing rather than retarding bacterial growth. Perhaps as a second stage, milk or cream would be good too - again, a high moisture food with known contents.

Best wishes.

Thank you so much Majid and Amy for sharing your vast knowledge with me. 

Majid, for your info, my MSc student is working on chitosan to preserve fresh fruits and vegetables. We could exchange info on this.

Amy, thanks to you and Jon Palmer recommendation. I will do the antibacterial study first before i proceed with its application on any food model.