Skip to content

ASTA Color Value Test — Standard Operating Procedure & Record

1. Purpose & Scope

This document describes the procedure for determining the ASTA (American Spice Trade Association) color value of paprika powder, flakes, and ground whole-pod subsamples using the ASTA 20.1 spectrophotometric method. The ASTA color value is the primary quality parameter for grading paprika and must be measured for every production batch.

Scope: All paprika products (powder, flakes, whole pods tested as ground subsamples) at all grade levels.

2. Equipment & Consumables

Item Specification Notes
UV-Vis Spectrophotometer Wavelength accuracy ±1 nm at 460 nm Recommended: Shimadzu UV-1900, Thermo GENESYS, or equivalent
Cuvettes Quartz or optical glass, 1 cm path length Matched pair recommended; check optical clarity before use
Analytical Balance ±0.001 g precision Calibrated daily
Acetone ACS grade, ≥99.5% purity Store in airtight container; expires 3 months after opening
Volumetric Flasks Class A, 50 mL, 100 mL, 250 mL Clean, dry, acetone-rinsed
Volumetric Pipettes Class A, 1–10 mL range Calibrated annually
Filtration Whatman No. 1 filter paper or 0.45 µm syringe filter For cloudy extracts
Mortar and Pestle Porcelain or agate For grinding whole pods or coarse flakes
Thermometer ±0.5°C accuracy Measure acetone temperature
Vortex Mixer / Shaker Sufficient for 10 min extraction Mechanical shaker or vortex
Timer ±1 second For extraction timing

3. Detailed Procedure — Step by Step

3.1 Sampling

  1. Obtain a representative sample from the batch in accordance with the Incoming Inspection Procedure.
  2. For powder: use as-is. For flakes or whole pods: grind a subsample in mortar and pestle until it passes through a 40 mesh sieve.
  3. Store the prepared sample in an airtight, light-protected container until analysis.

3.2 Sample Preparation

  1. Weigh accurately 0.100 ± 0.010 g of prepared sample into a clean 100 mL volumetric flask. Record weight (m) to 0.001 g.
  2. Add approximately 70 mL of ACS-grade acetone at room temperature (20–25°C).
  3. Secure the stopper and shake vigorously by hand for 1 minute, then place on mechanical shaker for 10 minutes ± 30 seconds at moderate speed.
  4. Remove from shaker and dilute to volume (100 mL) with acetone. Invert to mix thoroughly.
  5. If the solution is cloudy, filter through Whatman No. 1 filter paper, discarding the first 5 mL of filtrate.

3.3 Measurement

  1. Turn on the spectrophotometer and allow to warm up for minimum 15 minutes.
  2. Set wavelength to 460 nm.
  3. Zero the instrument with a cuvette filled with pure acetone (blank).
  4. Rinse the sample cuvette with a small portion of the extract, then fill.
  5. Measure absorbance (A) at 460 nm. Record the reading.
  6. If absorbance exceeds 0.8 AU, dilute the extract with acetone (record dilution factor D) and re-measure.

3.4 Calculation

Formula:
ASTA Color Value = (A × D × V × 16.4) / (m × L × 100)

Where: - A = Absorbance reading at 460 nm - D = Dilution factor (D = 1 if no dilution; D = final volume / aliquot volume if diluted) - V = Volume of extract (mL) — typically 100 mL - 16.4 = ASTA conversion factor (extinction coefficient constant) - m = Sample mass (g) - L = Cuvette path length (cm) — typically 1 cm

Simplified (standard conditions: V = 100 mL, L = 1 cm):
ASTA = (A × D × 1,640) / m

3.5 Replicates

Perform the test in triplicate using three independently prepared extracts from the same sample. Report the mean of the three results.

4. Test Record Form

Lab Information
Sample ID
Product Name
Grade
Batch/Lot Number
Test Date
Operator
Ambient Temperature

4.1 Equipment Verification

Check Pass/Fail Notes
Spectrophotometer warmed ≥15 min
Wavelength set to 460 nm
Blank absorbance ≤0.010 AU
Acetone lot and expiry

4.2 Test Parameters

Parameter Value
Spectrophotometer Model
Wavelength 460 nm
Cuvette Path Length 1 cm
Solvent Acetone (ACS grade)
Sample Weight (g) [Replicate 1] / [Rep 2] / [Rep 3]
Extraction Volume (mL) 100
Absorbance Reading [Rep 1] / [Rep 2] / [Rep 3]
Dilution Factor [Rep 1] / [Rep 2] / [Rep 3]

4.3 Calculation

Parameter Rep 1 Rep 2 Rep 3
A (Absorbance)
D (Dilution factor)
V (Volume, mL) 100 100 100
m (Mass, g)
L (Path length, cm) 1 1 1
ASTA Result
Mean ASTA
Standard Deviation
% RSD

Acceptance: % RSD between replicates must be ≤5%. If exceeded, repeat the entire test.

4.4 Specification Check

Specification Mean ASTA Result Pass / Fail
Grade ASTA minimum [___]: [spec value]

5. Acceptance Criteria & Decision Rules

Condition Action
Mean ASTA ≥ specification minimum PASS — batch meets color specification
Mean ASTA < specification minimum by ≤5% HOLD — review by QC Manager; may reclassify to lower grade
Mean ASTA < specification minimum by >5% FAIL — batch cannot ship as stated grade. Reclassify or reject.
RSD between replicates >5% Repeat entire test; investigate technique or equipment issue

6. Calibration & Verification

Frequency Activity Standard / Reference
Daily Zero/baseline check with acetone blank Absorbance must be <0.010 AU
Weekly Wavelength accuracy check Holmium oxide / didymium standard
Monthly Full photometric accuracy NIST-traceable neutral density filter
Annually Manufacturer calibration service As per spectro. manufacturer SOP
Per new lot Acetone blank check Verify no interfering absorbance at 460 nm

7. Troubleshooting

Symptom Probable Cause Corrective Action
Absorbance >0.8 AU without dilution Sample mass too high Reduce sample mass to ~0.050 g and re-test
Absorbance <0.1 AU Sample mass too low, or very low color Increase sample mass; confirm sample is representative
Cloudy extract after filtration Incomplete grinding or moisture contamination Grind finer; use 0.45 µm syringe filter
Poor replicate precision (RSD >5%) Inconsistent weighing, extraction time, or cuvette handling Re-train operator; ensure 10.0 min shake time; clean cuvettes
Blank absorbance >0.010 AU Dirty cuvette or contaminated acetone Clean cuvette with acetone; use fresh acetone
Negative absorbance reading Cuvette mis-match or dirty reference Use matched cuvettes; clean both cuvettes
ASTA value seems too low vs visual color Possible capsaicin interference or old sample Check SHU; re-sample from fresh, sealed lot

8. Recording Requirements

  • All raw data (weights, absorbance readings, calculations) must be recorded in ink in the QC lab logbook immediately — no loose paper.
  • Digital records: enter results into LIMS within 24 hours.
  • Each entry must be dated and signed by the operator.
  • A second QC technician must review calculations for each COA release.

9. Method References

  • ASTA 20.1 — "Extractable Color in Capsicum Spices" — Official Analytical Methods of the American Spice Trade Association, 5th Edition
  • ISO 7543-2 — Chillies and capsicum oleoresins — Determination of total capsaicinoid content
  • ASTM D7481 — Standard Test Methods for Bulk Density

This document is part of the official technical documentation library for paprikabulk.com operated by Dinweys (Qingdao).Co.,Ltd. All rights reserved. For the latest version, visit paprikabulk.com.