Resistant starch: the patent landscape

With the rise in highly processed food products which reduce dietary fibre, the production and application of resistant starch in food have become a necessity. Resistant starch is applied to various food products, including medical foods and dietary supplements, in order to maintain colon health and the integrity of the gut mucosa. In some cases, it may also be used as a medicine. Recent studies have proved that resistant starch is capable of mitigating colon diseases, including cancer, as well as metabolic syndromes, including insulin resistance, hyperglycaemia, excess insulin, dyslipidaemia, abnormal blood fibre dissolution, diabetes, hypertension and cardiovascular disease. Augmenting its capabilities, researchers have introduced new applications for resistant starch, for example in fat replacers for controlling obesity.

Resistant starch
Food products containing carbohydrates – especially cereal-based foods, potato-based foods and the organs of some tropical plants – contain starch that provides the organism with necessary energy. Due to the amylolytic enzymes present in a human’s gastrointestinal system, starch undergoes hydrolysis; this results in rapid and complete digestion and absorption in the small intestine in the form of glucose. Some of the consumed starch is not completely digested and, either intact or in the form of the products of its partial hydrolysis, escapes the small intestine and enters the large intestine. This part of starch is called ‘resistant starch’.

Resistant starch is fermented in the large intestine, producing short chain fatty acids (SCFA) which serve as an energy source for colonic cells. Foods that increase the amount of SCFAs in the colon are thought to help prevent the development of abnormal cells in the gut.

Patent landscape
IP filings in this technology domain have increased at an average rate of 12.8% per year since 2000, with most patents filed in China, followed by the United States and Japan.

Several key factors (eg, a rise in health problems, public awareness and an increasing population) have caused an increase in:

• the demand for products such as cereal bars to contain high fibre and reduced calories to lower the glucose level in the blood;
• new products;
• scientific developments in the resistant starch field;
• new devices and preparation methods; and
• the market for resistant starch, which is expected to reach almost $14 billion by 2024.

The most active players in this domain are:

• National Starch and Chemical Investment Holding;
• Sudzucker;
• MGP Ingredients;
• Tate & Lyle;
• Cargill;
• Danone; and
• Penford.

Overall, the patents in this technology domain focus on:

• improving conventional manufacturing methods for making resistant starch from different sources, such as pressure-heat treatment, enzymatic or acid-release treatment, extruded treatment, microwave bulking treatment method and an ultrasonic method;
• improving the properties of resistant starch (eg, temperature resistance);
• improving the method of measuring resistant starch;
• increasing high dietary fibre;
• reducing the content of chemical substance; and
• reducing manufacturing costs.

Patent filings in this domain indicate that, before 2000, inventions were focused primarily on manufacturing resistant starch and the chemical modification of starch to inhibit its digestibility.

Between 2000 and 2005, the majority of inventions were focused on preparing resistant starch (especially type 3) which contains acid or acid salt. There was a particular focus on resistant starch containing alpha-amylase.

Between 2005 and 2013, research began to centre on modified starch, for example pectin-modified resistant starch that is prepared by cross-linking starch with pectin through a pectinesterase reaction. Research also focused on improving the properties of resistant starch, such as enhanced emulsion stabilities, thermal stability and hot and cold water swelling capacities in water, oil and other aqueous systems. Several patents focusing on improving the methods and techniques for preparing resistant starch (eg, retrograded resistant starch prepared through electrolysis, microwave and ultrasonic methods) were also filed during this period; this is due to the increased emphasis on reducing calories and increasing fibre in food products.

From 2014, research has focused on the production of resistant starch without the use of chemical additives. New applications include the resistant starch in various food products, such as cereal bars, rice jellies and other processed foods.

In 2016, China filed patents that concentrated on using resistant starch in foods such as fish balls and beef balls, and extracting resistant starch from seaweed.

New innovative applications and developments in resistant starch technology were introduced in 2017. Notable developments include the following:

• The use of resistant starch for the wall material of microcapsules, so that when they pass through the stomach and small intestines the core material is protected from harm caused by gastric juice and the small intestines, and probiotics can be released in the large intestines.
• An increase in the content of resistant starch in rice. The activity of the starch branching enzyme IIb (SBEIIb) protein in rice can now be inhibited using the CRISPR-Cas9 technology, in which the SBEIIb genes are edited at fixed points. The SBEIIb genes are knocked off by causing frameshift mutation, creating a new generation of rice germplasm with an increased content of amylase and resistant starch.

The patents in this technology domain mainly focus on resistant starch in rice, bananas, chestnuts, yams and milk for making products such as rice cakes, ice cream and biscuits. Some examples of other patent disclosures are:

• salad dressing containing pea resistant starch;
• lotus seed resistant starch;
• corn resistant starch;
• manihot esculenta resistant starch;
• chestnut resistant starch;
• longan seed resistant starch;
• yam resistant starch;
• xylitol tea oil resistant starch biscuits for diabetes patients;
• gluten-free resistant starch;
• colourless resistant starch;
• a method for extracting resistant starch (eg, from yellow wine lees through ultrahigh pressure and ultrasonic assisted treatment); and
• resistant starch packaging.

Chinese R&D
Chinese research is mainly focused on:

• the manufacturing method of resistant starch by adopting alpha-amylase;
• the preparation method for esterified resistant starch;
• the preparation method and application of a high temperature-resistant starch-based scale inhibitor; and
• preparing resistant starch  by disbranching low amylose starch and high-fibre cookies containing inulin and resistant starch, and other food or drinks using the same method.

Universities and research institutes supply the bulk of patents, with Jiangnan University, Fujian Agriculture and Forestry University and Zhejiang University leading the field.

Among the new entrants that emerged in 2017, most belong to China. The notable ones are:

• Fujian Agriculture and Forestry University;
• Zhengzhou Guoshi Technology;
• Maanshan City Huang Chi Food; and
• Wuhan Healthcare Biotechnology.

Comment
There is a variety of starches available from plants and other sources, of which only a handful have been studied. To realise the full potential of resistant starch, research must be conducted into the effects of these starches on the human body and their effectiveness in the prevention and control of diseases.

With new innovative technologies (such as the CRISPR-Cas9 system which is primarily used for genome engineering to enhance properties of resistant starch) it will be interesting to see how key industries compete with each other and strengthen their portfolios by filing similar patents in response to the questions surrounding this technology – for example:

• How can the properties of resistant starch be further improved?
• Which alternative industries have the potential to penetrate the resistant starch market and how can existing major players collaborate and merge with them?
• What could be the possible applications of resistant starch in the food industry without affecting medication or other food ingredients?