Reading/interpreting scientific journals/articles

I would like to know when Reading/interpreting scientific journals/articles, the authors often list materials/ingredients used as %. Is the given % the amount of the ingredient over the weight of the total formula(all the ingredients) or as a % of the key/main ingredient like in bakers % (% of flour weight) and MC style? Most of the articles don't seem to clearly indicate which is the percentage model they use. Also, articles sometimes list the % followed by (w/w) or (w/v) or (v/w), what does this mean?,thank you!

http://onlinelibrary.wiley.com/doi/10.1111/j.1745-4573.1996.tb00594.x/abstract, http://www.sciencedirect.com/science/article/pii/S030881460900243X, http://www.sciencedirect.com/science/article/pii/S0260877410003377 are some articles in which the % are confusing me.

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Comments

michaelnatkin

If a scholarly article doesn't say, it is very likely that they mean % to be as a percent of the total weight, not a baker's percentage. But it should be easy to tell at least if a full recipe is given -- if all the ingredients add up to 100%, then it is total weight. If there is one main ingredient that either doesn't have weight or has a weight listed of 100%, then the whole thing is in baker's percentages. In the example extracts you gave, they are almost certainly % of total weight.

w/w means weight/weight, and w/v means weight per volume, i.e. 28 g per liter. Here's a good explanation: http://www.thechemicalblog.co.uk/what-do-vv-ww-wv-andvw-mean/

michaelnatkin

Also note that for small percentages like you use with most technical ingredients, the difference between actual and baker's percentage is pretty trivial. i.e. let's say you were supposed to add 2 baker's percent of some ingredient to 100 g of water, but you thought it meant 2 total percent. You'd have added 2 g and you were supposed to add: 2.04 g, so you only made a 2% mistake - in most culinary cases not that big of a deal.

Imee_34011

oic. thanks michael. i think that helps.

Pepijn_31744

@Michael Natkin is right.

w/w is weight per weight, w/v is weight per volume and v/w is volume per weight. See also: link

w/w is the most used as far as I know.

For example:

1% (w/w) of liquid soy lecithin in 1 kilo of solution = 10 gr. soy lecithin per 1 kilo of solution
1% (w/v) of liquid soy lecithin in 1 litre of solution = 10 gr. soy lecithin per 1 litre of solution
1% (v/w) of liquid soy lecithin in 1 kilo of solution = 10 ml soy lecithin per1 kilo of solution

edit: should've read Michaels comment better.

Pepijn_31744

The difference between bakers percentage and actual percentage, becomes more relevant as you have more than one ingredient

100 gr. water (100%) or (55.2%)

80 gr. broccoli (80%) or (44.2%)

1 gr. xanthan (1%) or (0.6%)

adding 1% (w/w) results in 80% more Xanthan than when using the bakers percentage (1% of 181.8 vs. 1% of 100)