A food science mystery surrounding onions that has puzzled researchers for many years may have finally been resolved. Onion enthusiasts may sympathise with the unpleasant discovery of a strange bitter taste in their onions from time to time, despite being from the same bag as regular tasting onions. This phenomenon becomes apparent when you cut into an onion and discover that it looks normal but smells wrong. Up until now, very little was known about this strange occurrence.

Past researchers had delved into the flavour profiles of onions and discovered compounds such as lachrymatory factor synthase (known for making you cry) and several sulphur-based compounds, but none which caused that recognisable bitter taste.

Recently though, researchers have discovered nine new compounds in onions which only develop after an onion has been damaged or processed. The scientists put regular brown onions through a kitchen juicer and performed high performance liquid chromatography (HPLC) to determine the compounds which formed over time in the juice.

The researchers found that after 30 minutes, the juice started to develop a strong, bitter taste. After digging a little deeper they found that the onion produced nine different groups of sulphur-based compounds in the juice, which they dubbed allithiolanes. These compounds were found to form spontaneously once an onion is damaged and are not limited to onions. Related plants such as leeks, shallots and garlic were also found to produce these compounds after being damaged. This recent news simply adds to the complexity and wonder of the onion, and peels back one more layer of this wondrous food.

M&P Engineering is a leading manufacturer of food processing equipment including the world-famous Large Onion Peeling Machine, alongside Rotary Transfer Units, Sachet Filling Machines and Freshcut Machinery. M&P Engineering has over five decades of experience in the design and manufacture of food processing systems for its clients worldwide.

M&P Engineering is also home to the small onion peeler which uses a patented dry system for removing the outer skin, resulting in no slurry and a peeled onion similar in quality to hand peeled at production speeds. These machines are original Mather and Platt onion peelers and can top, tail and peel onions from 18mm to 45mm. If you would like to find out more information about M&P Engineering’s small onion peeler, call on +44 (0)161 872 8378 or contact us here.

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