Pattern Recognition Approach for the Screening of Potential Adulteration of Traditional and Bourbon Barrel-Aged Maple Syrups by Spectral Fingerprinting and Classical Methods

At a Glance

Metadata	Details
Publication Date	2022-07-25
Journal	Foods
Authors	K. J. Zhu, Didem Peren Aykas, Luis Rodriguez‐Saona
Institutions	The Ohio State University, Adnan Menderes University
Citations	6
Analysis	Full AI Review Included

Technical Documentation & Prospectus: Diamond-Enabled Vibrational Spectroscopy for Rapid Food Authentication

Executive Summary

This research validates the use of portable Fourier Transform Infrared (FT-IR) and Raman spectroscopy, underpinned by robust diamond crystal technology, for the rapid, non-destructive authentication of premium food products. The findings are highly relevant to the quality control, authentication, and miniaturization objectives of the food and beverage industry, showcasing the indispensable role of Chemical Vapor Deposition (CVD) diamond materials.

Application Focus: Non-destructive, fast detection of adulteration (ingredient tampering) in high-value traditional and Bourbon Barrel-Aged (BBL) maple syrups.
Enabling Technology: Portable FT-IR using a triple-reflection Diamond ATR crystal and a compact benchtop Raman system (1064 nm laser).
Key Achievement: Successful classification (100% sensitivity/specificity) of authentic syrups from suspicious, adulterated samples (15% incidence in test set) using Soft Independent Modeling of Class Analogy (SIMCA).
Quantifiable Results: Partial Least Squares Regression (PLSR) models demonstrated strong correlations (Rval > 0.95) for predicting crucial quality metrics (°Brix and Sucrose content).
Material Necessity: Diamond was selected for the ATR crystal due to its chemical inertness, high durability, and wide spectral window (4000-700 cm^-1), enabling reliable, real-time analysis of viscous food matrices.
Value Proposition: The method provides a cost-effective, field-deployable alternative to traditional, time-consuming lab methods (HPLC, GC-MS) for quality assurance.

Technical Specifications

The following hard data points detail the instrumentation and performance metrics achieved using the vibrational spectroscopy approach enabled by CVD diamond components.

Parameter	Value	Unit	Context
FT-IR ATR Crystal	Diamond (Triple-Reflection)	Material	Provides chemical robustness for viscous/corrosive samples.
FT-IR Spectral Range	4000 to 700	cm^-1	Mid-infrared analysis range.
FT-IR Resolution	4	cm^-1	Standard spectral resolution utilized.
ATR Penetration Depth	~6	µm	Depth of analysis into the syrup sample.
Raman Excitation Laser	1064	nm	Used to minimize fluorescence interference from colored samples.
Raman Spectral Range	350 to 1500	cm^-1	Fingerprint region analyzed.
Raman Resolution	4	cm^-1	Standard spectral resolution utilized.
FT-IR °Brix Rval	0.98	Dimensionless	External Validation correlation coefficient (Excellent).
Raman °Brix Rval	0.96	Dimensionless	External Validation correlation coefficient (Strong).
FT-IR Sucrose Rval	0.99	Dimensionless	External Validation correlation coefficient (Exceptional).
FT-IR °Brix SEP	0.88	%	Standard Error of Prediction.
Raman °Brix SEP	1.23	%	Standard Error of Prediction.
SIMCA Classification	100	%	Sensitivity/Specificity in identifying adulterants.

Key Methodologies

The experiment successfully leveraged robust spectroscopic analysis, confirming the suitability of diamond-based ATR for non-destructive, rapid testing of complex food matrices.

Sample Preparation: Traditional (n=23) and BBL-aged (n=17) maple syrup samples were stored at 4°C, then equilibrated to room temperature (RT) prior to analysis.
Reference Analysis (Verification): Samples were characterized by standard lab methods: HPLC (for sugar content: sucrose, fructose, glucose), Refractometry (°Brix at 22°C), GC-MS (for volatile compounds like ethanol and isoamyl alcohol), and Folin-Ciocalteu (FC) method (for total phenolics).
FT-IR Acquisition (Diamond ATR):
- A portable FT-IR system equipped with a triple-reflection diamond ATR crystal and a ZnSe beam splitter was used.
- Approximately 0.2 g of syrup was applied directly to the 2 mm diameter sampling surface.
- Spectra were collected from 4000 to 700 cm^-1 at 4 cm^-1 resolution. Sixty-four scans were co-added for signal-to-noise ratio improvement.
Raman Acquisition (Benchtop):
- 3 mL of syrup was placed in a 10 mm path length quartz cuvette.
- A compact benchtop Raman spectrometer utilizing a 1064 nm laser (InGaAs detector) was used to mitigate sample fluorescence.
- Spectra were collected from 350 to 1500 cm^-1 at 4 cm^-1 resolution. Three scans were co-added with a 3-second integration time.
Data Processing: Spectra were preprocessed using mean-centering and the Savitzky-Golay (SG) algorithm (35-point filter) to reduce noise and enhance spectral features.
Chemometric Modeling: Supervised pattern recognition (SIMCA) was used for classification (authentication), and quantitative analysis (PLSR) was used for predicting °Brix and sugar content.

6CCVD Solutions & Capabilities

The successful implementation of this advanced food authentication technique relies directly on the superior material properties and precision engineering of high-purity CVD diamond, the specialty of 6CCVD.

Applicable Materials

The foundation of the high-performance portable FT-IR system is the robust ATR element. Replicating or advancing this research requires high-quality, ultra-low absorption CVD diamond.

6CCVD Material	Specific Requirement from Paper	Relevance & Customization
Optical Grade Single Crystal Diamond (SCD)	Triple-reflection ATR crystal (Section 2.3.1)	Required for maximal transmission efficiency and minimal internal scattering across the mid-IR range (4000-700 cm^-1). Our SCD offers high purity essential for high-resolution spectroscopy.
Polycrystalline Diamond (PCD) Wafers	Durable wafer support structures	High thermal conductivity PCD can be used in detector or beam splitter supports to ensure thermal stability of the portable system during field use, enhancing spectral integrity.
Custom Thickness SCD/PCD	ATR crystal thickness (Substrates up to 10mm)	We provide SCD plates up to 500 µm thickness and substrates up to 10 mm, allowing engineers to design optimal ATR geometries for specific angle-of-incidence and energy transfer requirements.

Customization Potential

The performance of an ATR crystal is highly dependent on its physical geometry, surface quality, and integration tolerances. 6CCVD’s specialized services directly address the precision requirements for high-end vibrational spectroscopy hardware:

Precision Polishing: We offer ultra-smooth SCD surfaces with roughness Ra < 1 nm and large-area PCD polishing with Ra < 5 nm. This surface finish is critical for maximizing light throughput and reducing signal scattering in ATR setups.
Custom Dimensions and Shaping: We can provide diamond wafers and plates in custom dimensions up to 125 mm (PCD), tailored to fit unique sample compartments or instrument designs (e.g., custom sizes for the 2 mm diameter sampling area mentioned in the paper).
Advanced Metalization: While the primary component here is the optical diamond, we offer in-house metalization (Au, Pt, Ti, W, Cu) for electrodes, thermal sinks, or integration into micro-electromechanical systems (MEMS) detectors (like the DTGS detector mentioned).

Engineering Support

6CCVD’s in-house PhD engineering team possesses deep expertise in the physics and application of diamond across extreme environments, including sophisticated optical systems. We can assist researchers and instrument developers looking to:

Optimize ATR Design: Selecting the optimal SCD crystal orientation, thickness, and surface geometry for improving signal-to-noise ratios in challenging mid-infrared food analysis projects.
Develop Integrated Sensors: Providing material selection consultation for miniaturizing portable analytical systems focused on vibrational spectroscopy and chemical authentication.
Ensure Regulatory Compliance: Assisting in material specification required for robust, field-deployable quality control devices in the food, beverage, or pharmaceutical industries.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

This study aims to generate predictive models based on mid-infrared and Raman spectral fingerprints to characterize unique compositional traits of traditional and bourbon barrel (BBL)-aged maple syrups, allowing for fast product authentication and detection of potential ingredient tampering. Traditional (n = 23) and BBL-aged (n = 17) maple syrup samples were provided by a local maple syrup farm, purchased from local grocery stores in Columbus, Ohio, and an online vendor. A portable FT-IR spectrometer with a triple-reflection diamond ATR and a compact benchtop Raman system (1064 nm laser) were used for spectra collection. Samples were characterized by chromatography (HPLC and GC-MS), refractometry, and Folin-Ciocalteu methods. We found the incidence of adulteration in 15% (6 out of 40) of samples that exhibited unusual sugar and/or volatile profiles. The unique spectral patterns combined with soft independent modeling of class analogy (SIMCA) identified all adulterated samples, providing a non-destructive and fast authentication of BBL and regular maple syrups and discriminated potential maple syrup adulterants. Both systems, combined with partial least squares regression (PLSR), showed good predictions for the total °Brix and sucrose contents of all samples.

Tech Support

Original Source

DOI: https://doi.org/10.3390/foods11152211

References

1891 - The Maple amongst the Algonkian Tribes [Crossref]
1996 - The chemical composition of 80 pure maple syrup samples produced in North America [Crossref]
2014 - Comparative analysis of maple syrup to other natural sweeteners and evaluation of their metabolic responses in healthy rats [Crossref]
2019 - Astringency, bitterness and color changes in dry red wines before and during oak barrel aging: An updated phenolic perspective review [Crossref]
2002 - Discrimination and classification of adulterants in maple syrup with the use of infrared spectroscopic techniques [Crossref]
1980 - Detection of Adulterated Maple Products by Stable Carbon Isotope Ratio [Crossref]
1995 - Maple Syrup Authenticity Analysis by Anion-Exchange Liquid Chromatography with Pulsed Amperometric Detection [Crossref]