Starch is a versatile and cost-effective material with various industrial applications in both food and non-food sectors. It is widely used in the food and paper industries, with the majority of produced starch going to the food sector. Modified and native starches are the most commonly used hydrocolloids in food systems. Starch is used to make syrup and ready-made meals, sauces, and sweets, among other things.
Worldwide, more than 30 million tons of natural and modified starches are used in the production of dextrin, food ingredients, paper coatings, and adhesives. In Europe, the majority of produced starch is used in sweeteners and hydrolyzed products. In the United States, most of the production is not for native and modified starch but for sweeteners, particularly high fructose corn syrup.
There has been a growing demand for modified starches in recent years, mainly produced in North America and Europe, with Europe being a leading producer. Asian markets demand large amounts of starches used in fermentation, while the United States has focused on starch for biofuel production. Non-food industries are experiencing a faster growth in demand for starch compared to food industries.
Food Applications
Starch is a critical energy source for plants, and it accounts for 70 to 80% of the calories that humans consume. The food industry heavily relies on starch as a key ingredient, as it provides essential functional and nutritional properties to many foods. However, starch is not limited to food production, as it is also utilized in various ways in the food and beverage sectors. Despite the extensive analysis of starch usage in the food industry (Eliasson, 2004; BeMiller, 2007), this article aims to provide a general overview of the main trends in how starch is employed in food products.
Starches and Their Derivatives in the Food Industry
Starches and their derivatives are widely used as ingredients in the food industry to enhance the properties of food products. They are used in small or large amounts to improve the texture, consistency, and overall quality of food. The structure of starch is critical to its function, and as such, various chemical and technological methods are used to modify the structure of starch to achieve specific outcomes.
Choosing the right starch for food applications requires considering several factors, including food processing technology, functional, sensory, and rheological properties of the starch, and other ingredients that will be used. Native and modified starches are commonly used in foods due to their thickening and gelling properties. Native starches can have high viscosity, limiting their use to less than 6% solids in most cases. Additionally, some native starches may exhibit undesirable properties under certain process conditions such as temperature, pH, or pressure.
Modifications of starch structure using chemical, physical, and enzymatic methods can enhance properties like resistance to high shear rates, thermal decomposition, high retrogradation, and syneresis. For instance, physically modified starches like pregelatinized starches are popular in the food industry as they do not require cooking and can maintain rheological properties. They are used in instant dry mixes like instant pudding, baby foods, frozen foods, and convenience products. Other modified starches like oxidized starches are used in products demanding softness and transparency, like gum sweets or Arabic gums.
Acetylated starches are widely used in the food industry to prevent unwanted changes in product texture and appearance caused by retrogradation during food processing and storage. They are used in many baked goods, canned pie fillings, sauces, condensed soups, frozen foods, baby foods, salad dressings, and snack foods. Succinate derivatives are used as binders and thickening agents in soups, snacks, and canned and refrigerated food products. Hydroxypropylated starches improve the shelf life, freeze–thaw stability, cold-storage stability, clarity, and texture properties of starch paste.
Cross-linking of starches is also a common method of modification to improve the product’s texture and resistance to rupture during processing. Cross-linked starches are more resistant to low pH, rupture, and high temperatures, and show high capacity for holding water. However, they may have reduced paste clarity and stability against cold storage. Further modifications like hydroxypropylation and acetylation are used to address undesirable characteristics of cross-linked starch.
In conclusion, starches and their derivatives play a critical role in the food industry, with various modifications to their structure to achieve specific properties. Understanding the functionality and properties of these starches is essential to selecting the right starch for food applications.
Starch Hydrolysis in the Food Industry
Starch hydrolysis is widely used in the food industry to convert starches, starch derivatives, and starch saccharification products into useful ingredients for food processing. These products have many applications and are considered healthy. They can be obtained through acid catalysis or specific enzyme action. In the past, industrial hydrolysis of starch was done using inorganic acids, but this process has been replaced by enzymatic hydrolysis, which is more specific and efficient. Enzymatic hydrolysis also produces more stable products and does not require steps to neutralize them. Additionally, the milder conditions for enzymatic catalysis reduce unwanted side effects and the formation of compounds with a bad taste or color.
The starch-processing industry is the second-largest market for industrial enzymes, with amylases, glucoamylases, and glucose isomerases being the most important enzymes used. These enzymes break down starch into sugar and change the shape of glucose molecules. The products from starch hydrolysis, such as glucose or maltose syrup and maltodextrins and their derivates by isomerization (iso-glucose and fructose), have many applications in the food industry. They are used in candy, sweet, chocolate, cake, dessert, dairy, and pastry products due to their anticrystallizing, sweetening, and water-holding properties.
Sugar syrups and their derivatives are the most popular hydrolyzed starch used in fermentation processes, beverage formulation, dietetic products, ice creams, soft gum, dairy products, desserts, and candies. Maltodextrins also have functional properties and are employed for their thickening properties, prevention of crystallization, control of freezing, and stabilization. Overall, starch hydrolysis is an essential process in the food industry that produces many useful ingredients with various functional properties.
Starch in Health, Nutritional, and Functional Food Products
The food industry is using starch in health, nutrition, and functional products, which has led to research for making new products like frozen, chilled, low-fat, and gluten-free foods. One trend is the use of high amylose starch as a source of resistant starch (RS) due to health nutrition trends emphasizing low glycemic foods with enhanced fiber consumption. RS resists digestion in the small intestines of healthy individuals and stimulates fiber action in the intestinal tract. This type of starch can replace fibers in food without affecting their sensory properties. Another trend is to reduce fat intake by improving the quality and sensory characteristics of low-fat products. Starch derivatives have shown to be promising fat replacements for improving texture, color, palatability, and stability of foods. Hydrolyzed starches, waxy starches, and cassava starch derivatives have been shown to be efficient fat replacers, with acetylated starches improving stability in low-fat systems. However, starches must maintain high moisture content in some systems such as mayonnaise, salad dressings, and low-fat spreads to replace fat effectively.
Development of Edible Films and Coatings for Shelf-Life Extension of Fruits and Vegetables
Edible films and coatings can be made from biopolymers like lipids, proteins, and derivatives of cellulose and starch. These materials have been tested for their ability to extend the shelf life of fruits and vegetables. To achieve this, there has been an increase in interest in the development of films and coatings that are edible. Starch gelatinized with NaOH, glycerol, or sorbitol can serve as plasticizers in these coatings and films. Additionally, a blend of pectin and high amylose corn starch has been suggested as a potential option for creating food coatings and films. Several studies, including Larotonda et al. (2004), Cyras, Zenklusen, and Vazquez (2006), and Dimantov, Kesselman, and Shimoni (2004), have explored these options.
Non-food Applications
Starch is a complex carbohydrate found in plants that has been used in various industries for many years. In the nonfood industry, the paper sector is the largest user of starch, with more than 10 million tons consumed each year. As the cost of cellulose pulp increases, paper makers are exploring cheaper fillers, which often require modified starches to adhere to the pulp. Innovations in modified starches have increased their share in paper coating, improving paper strength and printability. These starches are also used in laundry and textile finishing products.
Biodegradable polymers have gained interest in recent years as a potential solution to fossil resource limitations, recycling issues, and environmental concerns. Starch has emerged as a viable option due to its low cost, abundance, and renewability. Starch-based polymers have been used for packaging applications such as loose-fill containers, transparent films, and biodegradable bags. They are also used in products like cotton buds, toilet paper packaging, and plant pots. However, starch-based plastics have some limitations such as low moisture resistance and brittleness, which limit their use. Modified starches can address these issues by improving viscosity, texture, and stability.
Starch-based and biodegradable polymers have also been used in the production of automotive parts and as a biofiller to improve tire performance, reducing rolling resistance and fuel consumption. In the fuel market, starch crops are a source of bioethanol, but improvements in conversion technology are necessary to increase ethanol yield. The competition for corn in the biofuel market has led China to suspend further production of ethanol and other starch derivatives from corn to protect domestic food and feed consumption.