Lab Canada

Colour consistency in peanut butter

Sunland, a maker of peanut products in New Mexico, needed to ensure consistency of colour in its peanut butter. An essential factor in the ultimate determination of the peanut butter’s final grade, colour accounts for twenty percent of the total score when establishing the grade.

For the past 50 years, the United States Department of Agriculture (USDA) has issued standards for grading peanut butter. Factors for defining the different qualities of peanut butter include the specific peanut type, texture and style. The product is also sorted into three different grades, which are established with scientific testing.

The USDA established colour standards to enable the visual establishment of peanut butter that classifies as Grade A or Grade B or substandard. The process involves setting up specific lighting and viewing conditions, and product application and preparation method.

Sunland was formed in 1988 by a group of peanut farmers in New Mexico to market the Valencia peanuts they grew. The company’s market reaches from a retail store in Portales, NM, to around the world. In addition to processing raw, roasted, salted and unsalted peanuts, Sunland manufactures peanut butter.

Like all peanuts, Valencias are legumes, more closely related to peas and beans with one important difference: they grow beneath the ground. Valencias are smaller, sweeter and have more intense flavor than other varieties of peanuts.

Each peanut contains three to five kernels. The peanuts destined for the peanut butter plant are shelled and roasted, and most of the red skins removed. Then the peanuts go through several grinding and mixing areas.

Colour quality control


“The USDA provides four colour chips for peanut butter and we try to match our peanut butter colour to chip number three, with a plus or minus tolerance of .5,” said Samantha Rector, quality control supervisor with Sunland. “The private label peanut butter we make for other companies may require a different colour match. We needed a way to take the subjectivity out of colour matching, which was done visually according to USDA standards. I may see a batch of peanut butter colour as too dark, while someone else may see it as too light.”

“We learned of a new and more reliable method that had been developed by Konica Minolta to speed up the colour evaluation process on peanut butter while at the same time making the process more consistent and less subjective,” she added. The Konica Minolta CR400/410 series of colorimeters have the ability to program the USDA grades and colour-matching data of peanut butter into the instrument.

“Now we can take a measurement of either roasted peanuts or peanut butter in seconds, rather than relying on time-consuming visual evaluation,” she said. “We have eliminated the need for special sample preparation to colour standards and for special lighting and viewing conditions required to evaluate peanut butter visually.”

Consistency is the goal


The colour measurement instrument can be held in just one hand, and is capable of measuring, comparing, and pass/failing up to 100 targets and 1,000 samples. Available in a choice of apertures (8mm or 50mm), the series is suitable for measuring reflected colour and colour difference of ingredients, raw materials, finished products, powders, pastes and opaque liquids.

The CR-410 used by Sunland can accurately and consistently measure peanut butter in a standard attachment and report a single number corresponding to the established USDA peanut butter standard colour chips. The reported colour number will indicate whether the product is USDA grade A, grade B or substandard grade, and, in the case of Sunland, report a variance from the programmed colour requirement for their peanut butter. The peanut butter colour index meter comes with software that stores data from every batch and allows them to keep track of product statistics from batch to batch. A custom output report can be printed for every batch.

Sunland measures the colour of peanuts at the grinding stage and at the final peanut butter stage just before it is put into jars.

“Measuring ground peanuts helps us know where the colour is before processing into peanut butter,” said Samantha Rector.

Samples are put into Petri dishes and placed on top of the colorimeter and measured. Colour is adjusted by controlling the temperature at the roaster, according to the results of the measurement.

“Colourants are never used to adjust colour; it’s all pure Valencia peanuts,” said Rector. “The Konica Minolta CR-410 colorimeter has definitely saved us a lot of time and cost by eliminating trial and error and increased our productivity too.”

For more information, request # 15 online at