In our Ask Peter series, executive chef Peter Gordon answers your curly culinary questions. And then keep a record of what you used and use this as your “go-to” referral every time. With leaf gelatine - you’re best to only buy packets that instruct you clearly what they will set and then adjust your quantity accordingly. Generally, 7g of gelatine will set 500ml liquid 7g of powdered gelatine is around 2½ teaspoons. If you have a set of those very precise scales that coffee buffs seem to use these days when making the 'perfect espresso”, that can help. As to how much powdered gelatine is the equivalent to leaf gelatine - there is no simple answer as there are several quite differing varieties on the market.

The reason I’m pointing this out is that a fruit jelly made from fruit juice, or a panna cotta or bavaroise made from cream and milk, can vary enormously in how much gelatine is needed, with skim/trim milk needing more to set it than regular milk. With fruit juice, apple juice generally is very watery and is mostly water whereas tomato juice is much thicker, and like cream, has less water so needs less gelatine. Milk and cream (think panna cotta) are milk fats suspended in water - cream having more fat, and therefore less water - so it needs less gelatine to set it. There’s no solids or fats in water - just a few miniscule amounts of harmless chemicals like sodium, magnesium etc. For me the easiest way of describing this, which will affect how much gelatine you need for a recipe, is that water is 100 per cent pure liquid. The scientific part of what constitutes “liquid” is also worth pointing out. Writing cookbooks and knowing people around the world are feeling disappointed with the end result is also heartbreaking, as all my recipes work when made at home, which is where I always shoot them. Some will set a liquid much firmer than others, some will produce a more cloudy result than others, some need more soaking - or blooming, the term more often used for soaking gelatine. The more I looked into it the more complicated it became as not all gelatines are alike. They were thinner and smaller - which obviously meant one sheet was going to set much less liquid than mine. Well it turned out that the leaf gelatine he’d bought from the supermarket was quite different to the one we chefs were using in restaurant kitchens. Then one day I was talking to a friend, a keen home cook, and he said the panna cotta recipe I’d given him was too soft and he’d had to serve them in the mould rather than unmoulding. As to how many teaspoons set 100ml of liquid - I could never really figure it out. For years it was a very simple equation of one sheet to set 100ml liquid. Then on the scene appeared the miracle answer - sheets that you simply soaked in ice cold water for five minutes, before gently squeezing out the excess liquid and adding to a warmed liquid to dissolve them. It wasn’t in reality a huge problem but it caused me a few moments anguish from time to time.

Dissolving powdered gelatine had always been slightly tricky as I could never seem to get 100 per cent of the granules into the liquid I was trying to set - there would always be a few slightly undissolved ones stuck to the dish I’d soaked them in. When I first began using sheet, or leaf, gelatine in the late 80s I felt one of the culinary world’s hassles was forever answered. Is it true that the sheets are superior to the powder? I avoid making anything using gelatine as I think I am going to muck it up by buying/using the wrong thing. I am very confused about gelatine - many recipes use the sheet variety now but seem very loose on the amount, one sheet seems to do it all, whereas the powdered variety is measured out carefully.

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Gelatin leaves vs powder