Quantifying Limonene and Diacetyl Levels in Orange Juice

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Orange juice is a common breakfast beverage that is enjoyed all over the world. However, certain chemical compounds in orange juice, such as diacetyl and limonene, can not only affect the taste of the drink, but they are also potentially hazardous. These compounds can occur via microbiological contamination (due to poor processing), or via handling procedures.

Limonene is a colorless liquid hydrocarbon that is categorized as a ‘cyclic terpene’. It is a common d-isomer that smells strongly of oranges. It has a detrimental effect on cellular health if consumed for extended periods of time. Limonene also has been linked to neurodegenerative diseases and general cell aging.

Diacetyl, which is an organic compound, is a yellow or green liquid that has a buttery flavor. Its exposures could potentially lead to hazardous flavorings in orange juice (as well as in other fruit juices), due to its toxic properties.

These unwelcome materials do not usually affect flavor unless they are present in very high concentrations. Thus, it is important that manufacturers have a way of quantifying the presence of diacetyl and limonene in orange juice before it reaches customers.

California-based EST Inc. has developed a one-of-a-kind electronic nose, called the zNose®, which quantifies the concentration of hydrocarbons and reveals the presence of unwanted components in orange juice in under a minute. The zNose® is specifically designed to support quality control testing of aroma and flavor in almost any food or beverage.

This novel technology can analyze the chemistry of any vapor beyond the range of C4-C20 using a 1-meter db-624 capillary column with any need for physical sensors. In under one minute, it can speciate and quantify discrete chemicals found in any odor, smell, fragrance, or vapor with a part-per-billion sensitivity. Furthermore, the zNose® can create high-resolution visual olfactory images, called VaporPrints™, as well as hundreds of virtual chemical sensors simultaneously.

Testing Limonene & Diacetyl in Orange Juice

Testing Standards

  • For quantifying the presence of limonene & diacetyl in orange juice quickly, maintain the temperature programming as high as 18 °C per second.
  • Full hydrocarbon spectrum viewing within C4-C20 is achieved by ramping the db-624 column temperature from 40 °C to 140 °C in 10 seconds.
  • The highest resolution, however, is obtained using isothermal column conditions (40 °C to 150 °C).

Testing Limonene in Orange Juice

  • Clear the zNose® by applying Air Blank and 10 ps-0
  • Develop an orange juice standard
  • Using the orange juice standard, pre-concentrate headspace vapors
  • Analyze orange juice with the zNose® using 10 ps-0 method
  • Clear the zNose® using Air Blank and 10 ps-0 method

Testing for Diacetyl in Orange Juice

  • Clear the zNose® using the air blanks using 10 ps-0 method.
  • Develop diacetyl/orange juice standards.
  • Tenax absorber air blanks (170 °C) using 10 ps-0 method.
  • Chill the Tenax absorber to room temperature.
  • Pre-concentrate headspace vapors using diacetyl/orange juice standard.
  • Dry the tenax absorber and elevate it to 170 °C.
  • Analyze tenax vapors using the zNose® using 10 ps-0 method.
  • Tenax absorber air blanks (170 °C) using 10 ps-0 method.

The zNose® can sense and quantify the presence of harmful components, such as limonene and diacetyl, in orange juice in under a minute, with precision and accuracy. Furthermore, it can carry out over 300 measurements daily, which makes it a cost-effective quality control tool with a payback period of 30 days (in the majority of situations). The zNose® is a useful and practical device that promises a one-stop solution for quality checking, while providing consumers with a healthy and safe taste of nature.


This information has been sourced, reviewed and adapted from materials provided by Electronic Sensor Technology.

For more information on this source, please visit Electronic Sensor Technology.

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