How do they get the soft centres into liqueur chocolates and after-dinner mints? With invertase, naturally.
HOW IS IT DONE?
A solid paste with the consistency of fudge is made using sucrose (table sugar). A small amount of invertase is added to this fondant before it is enrobed in chocolate. During storage for a couple of weeks at 18 °C, the enzyme partially liquefies the sucrose within the chocolate shell.
HOW LONG HAVE MANUFACTURERS BEEN USING THIS METHOD?
A US government chemist, H.S. Paine, first suggested this method in 1924. Modern machinery (that freezes the half-shell) allows syrupy centres to added to pre-cast chocolate shells (such as fondant-filled Easter eggs - aka 'Creme eggs' in the UK), removing the need for enzymatic treatment.
WHERE CAN I FIND OUT MORE
The following publication briefly mentions the use of invertase in sweet-making:
McGee on food and cooking by Harold McGee (2005) Hodder and Stoughton. ISBN: 0 340 83149 9.
The University of York Chemical Industry Education Centre has an excellent practical booklet, 'Sweet success', aimed at 14-16 year-olds on the production of Creme Eggs:
A more advanced general booklet for schools is Enzymes and their role in biotechnology by Paul Wymer and A. Teal. This is one of a series of booklets aimed at post-16 students produced by the Biochemical Society and available from their Web site:
The 16 chromosomes of S. cerevisiae's genome have been sequenced. Information is available from these Web sites:
Information about invertase can be found at the second of these sites.
Invertase is produced by baker's yeast, Saccharomyces cerevisiae.
Safety guidelines for practical work with enzymes in schoolscan be found here.
The NCBE supplies these enzymes to schools and colleges for educational use. Commercial users of enzymes or those requiring enzymes for research purposes should contact the enzyme manufacturers, not the NCBE.
Invertase (also known as sucrase or saccharase) splits the disaccharide sucrose into the monosaccharides glucose and fructose. Invertase is inhibited by high concentrations of its substrate, sucrose.
The invertase we supply has optimum activity at 60 °C. Its optimum pH is 4.5 (the pH is usually adjusted to this level by the addition of citric acid to the reaction mix), although it is active between pH 3.0 and 5.5. Inactivation of the enzyme begins at 65 °C and the enzyme is totally inactivated after 5 minutes at 90 °C.
The enzyme preparation should be stored at 3-5 °C. At this temperature the enzyme will maintain its declared activity for at least a year.
INVERTASE PREPARATION (Liquid)
Invertase (Maxinvert L 10 000).... 100 mL .... £13.50 (GBP)
Please note: All the prices on this page are in GBP and do not include Value Added Tax (VAT). This tax applies within the European Union only. Postage and packing must also be paid on orders from outside the United Kingdom.
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