Source of GI data
The glycemic index (GI) values are sourced from Sydney University's Human Nutrition Unit website, whereas the nutrient data is sourced from FSANZ's database, and I've tried to match them for each food but there are variations in brands and test countries etc. so for the most accurate values for any food please check Sydney Uni's database.
Variability of GIs
Many of the foods tested multiple times have a considerable range of GI values, this is usually due to actual natural variation within foods and not measurement errors. For some foods, potatoes for example, the method of preparation and storage can have a big affect too. Please refer to the GI website for more info.
I've tried to include the value closest to the average, and for foods tested only 2 or 3 times I include the Australian source when available.
Please just use these GI values as a rough guide, the Glycaemic Load of your meals is more important. And don't read too much into differences among individual food varieties - eg, fresh vs canned fruit, differences of 10 or 20 may or may not be real and are certainly not very important.
Glycemic load values
The glycemic load (GL) is defined as the grams of available carbohydrate in the serve multiplied by the food's GI divided by 100, so the value is dependant on the serving size. Often GL values are presented for 'standard' serving sizes (I'm not sure universally standard serving sizes exist), but the values in this food table correspond to the load of 1 Zone carbohydrate block.
Take an apple for example – a single Zone block of carbohydrate is half an apple and has a glycemic load of 3, so a whole apple has a glycemic load of 6.