Color Measurement of Wine

and Wine is a traditional, natural product where color variation is expected and accepted. High color comes from high anthocyanin content and high tannins associated with red wines. Color varies with wine processing practices, particularly fermentation temperature. Co-pigmentation in wine and berry colors (related to presence of anthocyanins) enhances the wine color. Continue reading

What is Hunter Whiteness Index?

Hunter Whiteness Index [WIH]

There are at least half a dozen whiteness indices in use today, and a similar number of legacy whiteness indices no longer in use. There are subtleties among them and it is important to know the forms of these whiteness metrics and conditions for which they are derived for. In general, a material will exhibit high whiteness if the material reflectance has high and even reflectance, near 100%, across the visible spectrum.

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Do you have a source for EP Opalescence Standards?

The reference document that defines the visual EP Opalescence scale is:

EP 2.2 Physical and Physico-Chemical Methods for color and opalescence

EP – European Pharmacopoeia, Section 2.2 Physical and Physico-Chemical Methods, Unit European Pharmacopeia, Strasbourg, France (1997: 15-16) http://www.pheur.org

This method describes the visual evaluation of scattering or opalescence in near clear liquids, typically pharmaceutical, relative to distilled water being a perfect clear.

There are two types of physical liquid standards for visual turbidity or opalescence – Formazin solution (with or without stabilizer) and polymer beads (polystyrene micro spheres). The Formazin solution is the historical liquid scattering standard but the polymer beads is considered more stable and homogenous.

Section 2.2.1 Clarity and Degree of Opalescence of Liquids in the EP 4th edition defines a Formazin Primary Opalescent Liquid Suspension (rated at 4000 NTU per EP 5th edition) as a solution of hydrazine sulphate solution and hesamethylenetetramine solution which is stable for 2 months stored in glass.

The EP 4th edition further defines a Formazin Standard of Opalescence (rated at 60 NTU per EP 5th edition) as a dilution of 15.0-ml of the Formazin Primary Opalescent Liquid Suspension (4000 NTU) to 1000.0–ml of water. This suspension must be freshly prepared and stored for no more than 24 hours.

To make the EP Reference suspensions or OP – Opalescence standards, the Formazin Standard of Opalescence (60 NTU) is mixed with distilled water in the following proportions to define 4 levels of liquid EPOP Opalescence Standards. Distilled water is nominally a fifth EPOP standard defining no opalescence or scattering.

Table 2.2.1-1 EPOP Standards 0 I II III IV
 Formazin Standard of Opalescence (60 NTU) 0.0 ml 5.0 ml 10.0 ml 30.0 ml 50.0 ml
Distilled Water (fill to 100.0 ml mark) 100.0 ml 95.0 ml 90.0 ml 70.0 ml 50.0 ml
NTU Rating 0 3 6 18 30

Sources for EPOP Liquid Opalescence standards are:

Hach Company

Loveland, CO 80538 USA

+970-669-3050

www.hach.com

Hach offers the STABLCAL Reference Suspension Set that consists of a range for EP Opalescence Standards per EP is 0 (distilled water >0.1), 3, 6, 18, 30 NTUs. Given the 2-year stability, stabilizers will have been added to these liquid EP standards.

Hach STABLCALC set of EP Opalescence Standards

Hach STABLCALC set of EP Opalescence Standards

Another source for the Formazin Primary Opalescent Liquid Suspension (rated at 4000 NTU) and EPOP Liquid Opalescence standards (rated at 0 – ­30 NTU) is:

RICCA Chemical Company

Arlington, TX 76094 USA

+817-461-5601

www.riccachemical.com

Reporting of EP Opalescence using a HunterLab Sphere Instrument and EasyMatch QC Software

As of EasyMatch QC version 4.82 and higher HunterLab has implemented a correlation method to the EP Opalescence scale based on these standards and is able to report EPOP-10mm (D65/10) for liquid samples measured in a 10 mm path length transmission cell. EPOP values are reported to tenths of a unit, along with NTU values as well.

Is it possible to create ASTM traceable haze standards above 30%?

The current, available ASTM D1003 Haze Standards have nominal Haze% values of 1, 5, 10, 20 and 30 with air (transparent solids) or the transmission cell filled with DI water being 0 (transparent liquids). Here are some thoughts on further options. Continue reading

Can the color of Fresh Spaghetti Sauce be measured with Tomato Scores?

FAQ: “We have another question. Our current Standard for Fresh Spaghetti Sauce is to Run on the TK setting.

It appears as if the Product is Rather orange compared to our Crushed tomato product which is run on the TS setting resulting in a lower color.

What do you believe is the proper setting for Spaghetti Sauce?

The other thing I noticed is That the Calibration record does not have a TK result documented.” Continue reading

SPC Results for Diagnostic Didymium Filter Test

FAQ: “We take the results from the Didymium Filter Test on our HunterLab ColorQuest XT and plot them in an SPC chart over time to look at trends. We are seeing the 430 and 570 nm filters slowly decrease. Can you help us understand what may be occurring?” Continue reading

FAQs on White Tile Replacement for HunterLab sensors

FAQ: “One of our manufacturing departments has a ColorQuest XE that they use to monitor a process at-line. After we saw that their white tile appeared a bit dingy and scuffed, we recommended they get a new one. The new white tile came in, but it comes with a software CD.  My questions? Continue reading