HunterLab ColorFlex EZ Citrus Spectrophotometer

Overview

The HunterLab ColorFlex EZ Citrus Spectrophotometer is a dedicated benchtop spectrophotometer engineered for objective, repeatable color measurement of citrus juices—including orange, grapefruit, and lemon—according to the industry-standard Citrus Color Scale. It operates on the principle of reflectance spectroscopy using a fixed 45°/0° optical geometry, where annular 45° illumination ensures uniform light distribution across the sample surface, and the 0° detector captures diffuse reflectance without specular contribution. This configuration eliminates directional bias and enhances reproducibility for viscous, semi-transparent liquids such as juice concentrates. Unlike subjective visual assessment, the instrument quantifies color in terms of Citrus Number (CN), Citrus Redness (CR), and Citrus Yellowness (CY)—empirically derived metrics calibrated against reference orange juice standards. Its spectral engine employs a diffraction grating and silicon photodiode array to deliver full-spectrum data (400–700 nm) at 10 nm intervals, enabling both proprietary citrus indices and standard color spaces (e.g., CIE L*a*b*, L*C*h°, Hunter Lab, XYZ, and sRGB) to be computed in real time.

Key Features

• Dedicated citrus color scale calculation: automatic derivation of CN, CR, and CY values per AOAC Official Method 967.12 and TTB compliance protocols for juice grading.
• 45°/0° optical geometry with integrated integrating sphere: optimized for low-gloss, semi-opaque liquid samples; minimizes influence of surface texture and meniscus variation.
• Compact footprint (15.2 × 22.9 × 25.4 cm): occupies less than 1/6 of standard lab bench space; designed for QC labs with high throughput and limited real estate.
• Sealed membrane keypad and large backlit LCD: resistant to juice spills and ambient lighting interference; displays numeric results, chromaticity diagrams, and spectral curves simultaneously.
• Onboard calibration verification: includes traceable plastic Orange Juice (O.J.) standard; supports daily instrument performance checks per ISO 9001 and GMP documentation requirements.
• RS-232 interface: enables direct connection to label printers for GLP-compliant hard-copy reporting or integration with LIMS via ASCII data export.

Sample Compatibility & Compliance

The ColorFlex EZ Citrus accommodates standard 12.7 mm (1/2-inch) diameter glass or disposable plastic cuvettes, as well as opaque solid samples (e.g., peel sections, pulp suspensions) when used with the optional reflectance stand. Its optical design inherently compensates for minor variations in juice turbidity and sugar content, making it suitable for both single-strength and reconstituted concentrates. The system conforms to ASTM D2244 (standard practice for calculation of color tolerances), ISO 7724-1 (colorimetry—part 1: CIE standard colorimetric observers), and FDA guidance for color evaluation in food and beverage manufacturing. All measurements are traceable to NIST-traceable ceramic tiles and liquid standards, satisfying internal audit and third-party certification requirements under SQF, BRCGS, and FSSC 22000 frameworks.

Software & Data Management

While fully functional as a standalone instrument, the ColorFlex EZ Citrus is compatible with HunterLab’s EasyMatch QC software (v5.0+). This Windows-based application enables comprehensive data management including: user-defined pass/fail tolerances with statistical process control (SPC) charts; batch-level reporting with timestamped audit trails; export to CSV, PDF, or Excel formats; and secure user access levels compliant with 21 CFR Part 11 (electronic records and signatures). Measurement history—including spectral scans, color coordinates, and pass/fail status—is stored locally with date/time stamping and operator ID logging, supporting full GLP/GMP traceability without requiring network infrastructure.

Applications

• Quality control of citrus juice blends during production and blending stages.
• Verification of concentrate strength and consistency prior to dilution or packaging.
• Raw material inspection of incoming fruit lots via peel or segment reflectance.
• Product development of new juice formulations requiring precise hue and chroma targeting.
• Regulatory submission support: generation of documented color data for TTB, USDA, or EU EFSA dossier requirements.
• Cross-functional use for non-citrus applications: dairy products, sauces, syrups, and pharmaceutical suspensions where 45°/0° geometry provides superior repeatability over sphere-based instruments.

FAQ

Is the ColorFlex EZ Citrus suitable for online (in-line) process monitoring?
No—it is a benchtop instrument designed for discrete, laboratory-based QC sampling. For in-line applications, HunterLab recommends the MiniScan EZ or UltraScan VIS with flow cell integration.
Can I measure pasteurized or clarified juice without filtration?
Yes. The 45°/0° geometry is insensitive to minor particulate scatter; however, highly pulpy or unfiltered samples should be centrifuged or filtered per AOAC 967.12 to ensure consistent path length and minimize measurement variance.
Does the instrument require annual recalibration by HunterLab service?
No. Routine verification using the included O.J. standard is sufficient for daily operation. Full recalibration is recommended every 12 months or after physical impact, per ISO/IEC 17025 accreditation guidelines.
What color spaces are calculated internally?
L*a*b*, L*C*h°, Hunter Lab, XYZ, YI (ASTM E313), WI (ASTM E313), and proprietary CN/CR/CY—all computed from raw spectral data without interpolation.
Is EasyMatch QC software included with purchase?
EasyMatch QC is available separately; the instrument ships with basic firmware and RS-232 drivers only. A perpetual license with technical support is required for full SPC and audit-trail functionality.