Ocean Optics offers a full menu of spectrometers, sensors and accessories for applications involving food and beverage processing, authentication and packaging. Our miniature spectrometers are compact, portable and flexible, with systems available for the lab, field and line.
With food fraud now a global problem, authenticating goods – from fruit and honey to spices and spirits – requires robust equipment based on sound science. Modular spectroscopy fills that role, with absorbance, reflectance, fluorescence and Raman spectroscopy systems used effectively for authentication and safety testing of foods.
Example Setup: Reflection from Apples
Reflection yields similar information to absorbance when applied to solid foods, with the depth of penetration being dependent on factors like the wavelengths used, sample composition and structure, and illumination source intensity. It has the benefit of being non-contact and noninvasive, and can be configured for a wide range of samples.
Bulk samples like meats and fruit are usually measured in a stand-off configuration, but a window is typically used for measurement of ground samples and powders. Rotating the sample is used to increase the measurement area and reduce error due to sample nonuniformity for coarse or large-particle samples like cereals, soybean or cornmeals, crushed processed foods and powdered foods or drinks.
The greatest amount of information can often be extracted about food quality or integrity when visible and NIR reflectance measurements are combined. Our Flame-S-VIS-NIR spectrometer is a good choice for detecting visible light, covering 350-1000 nm with ~1.5 nm resolution. It is complemented by the Flame-NIR spectrometer, which uses an uncooled 128 pixel InGaAs array to detect from 950-1700 nm with ~12 nm resolution. Together, these two spectrometers can provide detection from 350-1700 nm in a compact footprint with modest power consumption.
A reflection probe works well for measuring diffuse reflectance from foods. Depending on the food to be measured, it can be place at 90° or 45° to the sample. A fruit or meat sample might be measured at 90°, while powders would more often be measured at 45°. Measurements made with a reflection probe are relative measurements.
For granular samples or dense liquids, an angled reflection probe would work well. It is designed with a 45° angled window offset from the end of the reflection probe, allowing the light from the fiber to expand before illuminating the sample material. The window provides a consistent sampling surface, allowing the probe to be immersed directly into the powder or liquid to yield repeatable reflectance spectra.
A regular reflection probe also can be used in combination with a petri dish or microscope slide to look at powdered samples. Illuminating the petri dish or slide from below creates a flat sample surface at a consistent working distance from the reflection probe. A flat sample surface will give more consistent results with similar baselines as compared to reflecting off the uneven upper surface of the sample.
Dynamic sampling is often used for inhomogeneous samples such as grains, feed and soil. It uses rotational or linear motion to measure an “average” signal and remove localized variance from the results. Our dynamic sampling stage rotates the sample beneath the measurement probe and allows the probe to scan multiple areas over the sample, over multiple acquisitions.
The measurement system schematic below shows a 200 µm reflection probe (QR200-12-MIXED) and a special CSH probe holder for measuring a curved sample like an apple at 90° angle of incidence. One leg of this combined probe has a UV-VIS fiber for routing to the Flame-S-VIS-NIR spectrometer, while the other leg has a VIS-NIR fiber for routing to the Flame-NIR spectrometer, allowing both spectrometers to look at the same measurement point.
For illumination, we used the HL-2000 tungsten halogen light source (360-2400 nm), providing both visible and NIR illumination using a single light source. To complete the setup, we added a WS-1 reflectance standard as a reference and OceanView spectroscopy software.
|HL-2000||Tungsten halogen light source with continuous output from 360-2400 nm|
|QR200-12-MIXED||Expanded wavelength coverage reflection probe for simultaneous UV-Vis and Vis-NIR measurements|
|CSH||Probe holder for measuring reflection of curved surfaces|
|WS-1||Diffuse reflectance white standard|
|Flame-S-VIS-NIR||Vis-NIR spectrometer with Sony ILX511b detector for measurements from 350-1000 nm|
|Flame-NIR||Small footprint NIR spectrometer with uncooled InGaAs detector for|