Study validates new butanol test to quantify insoluble proanthocyanins

The newly recognised test will enable manufacturers to formulate new cranberry products beyond UTIs and create a higher bar for quality standards

Fruit d’Or is praising news that there is now a validated, published test method for quantifying insoluble proanthocyanins (PACs) found in whole fruit cranberry powder. The newly recognised test will enable manufacturers to conduct reproducible studies and explore new structure/function claims.

The Canadian company anticipates that the use of both whole fruit cranberry and cranberry seed powder to support gut health and overall wellness will be two strong areas of immediate research interest.

The study, published in the Journal of Agricultural and Food Chemistry, was conducted by Complete Phytochemical Solutions and Reed Research Group, Department of Animal Sciences, University of Wisconsin. The research team confirmed that insoluble cranberry PACs can be quantified using the butanol-hydrochloric acid method (BuOH-HCl) and a standardised (c-PAC) reference standard. Fruit d’Or provided the commercial cranberry products for the study.

Insoluble cranberry PACs

Insoluble PACs tend to cling tightly to fibres and proteins, making them difficult to extract and quantify. Although they may represent more of the cranberry by weight than soluble PACs, their importance to our health has not been well scrutinised.

“Historically, most cranberry-related health outcomes were associated with juice and juice-derived products which contained only soluble PACs,” noted Christian Krueger, CEO of Complete Phytochemical Solutions. “Insoluble PACs have been an under-represented/unappreciated component of cranberry fruit. Now that the industry has moved into whole fruit products, insoluble PACs come into the equation. With the butanol test method, we can do a better job of providing formulators, marketers and health researchers with more complete compositional information of their starting material.”

The method means we can do a better job of providing formulators, marketers and health researchers with more complete compositional information of their starting material

Stephen Lukawski, Director of Sales and Business Development for Fruit d’Or. “This newly accepted butanol test method will enable us to get a deeper understanding of cranberry’s health benefits, which will ultimately lead to higher sales of cranberry products.”

There are many benefits to having a recognised test method for quantifying insoluble cranberry PACs.


  • It opens doors to structure/function claims. These new analytics will enable study designs to determine if a unique structure is related to a health and nutrition function. “This can potentially result in structure/function claims related to insoluble PACs found in food, nutritional supplements and dietary ingredients,” noted Krueger.
  • It will enable the cranberry industry to make stronger inroads into the gut health category. Right now, no one knows for certain the role of insoluble PACs in the gut. There is speculation that, during digestion, they increase antioxidant activity in the colon. Now, researchers can look at how whole fruit cranberry consumption relates to a healthy microbiome. “Insoluble PACs could influence gut-level processes,” agreed Krueger. “To examine correlations, you need a good understanding of the composition of your test materials. The need for analytic methods is important.”
  • It will enable studies to be reproduced with more accuracy, building a stronger body of supporting evidence. Consistently using the accepted BuOH-HCl to identify, quantify and standardise the insoluble PACs in the starting raw materials will produce a more accurate understanding of the results, and enable others to replicate and verify those findings.
  • It gives the cranberry industry an entire analytics suite to support the composition, quantity and authenticity of soluble and insoluble cranberry PACs.
    • The 4-(dimethylamino) cinnamaldehyde (DMAC) assay, developed by Krueger, is the preferred method for quantification of soluble (extractable) PACs. This method was included in the 2016 American Herbal Pharmacopeia cranberry monograph, a guidance document for standards of analysis and quality control.
    • MALDI-TOF mass spectrometry is accepted for authentication of specific PAC structural features.
    • BuOH-HCl is now accepted for quantification of insoluble cranberry PACs.
  • It paves the way for higher sales and brand extensions. “Manufacturers will be able to generate more sales through validated claims and new product development,” observed Lukawski. “In addition to gut health, we may now find other cranberry components where insoluble PACs are found – such as the seed powder – that we can link fibre and protein to outcome studies.”

Lukawski says this test method is the final piece of the puzzle. “This is great news for the cranberry industry, especially researchers and formulators. It enables manufacturers to formulate new cranberry products beyond UTIs, generate greater sales and create a higher bar for quality standards.

“Fruit d’Or is in the whole fruit business. We are a zero-waste, sustainable company and believe in what mother nature has given us to work with. We want to understand all the components within the fruit, but we couldn’t do that without an accepted, validated test method for insoluble PACs,” Lukawski added. This is a foundational tool that will enable us to continue our work with researchers and scientists on the efficacy behind the cranberry. Our goal is to take cranberry beyond UTI and make it a lifestyle ingredient. Cranberry every day for everyone.”