Abstract
The development of gluten‐free bread innovations is driven by increased public awareness of healthy living, the rising number of individuals with celiac disease and gluten allergies, and efforts to reduce dependence on wheat imports by utilizing local commodities. Xanthan Gum (XG) and hydroxypropyl methylcellulose (HPMC) are commonly used hydrocolloids in gluten‐free bread because they have been proven effective in improving gluten‐free bread quality and mimicking the function of gluten in the bread matrix. This literature review aims to evaluate the roles of XG and HPMC in gluten‐free bread based on physical characteristics (specific volume, organoleptic properties, and color), texture, and nutrition. This study employs the Textual Narrative Synthesis method and PRISMA (Preferred Reporting Items for Systematic Reviews and Meta‐Analyses) technique, resulting in 41 selected studies after a comprehensive literature assessment. The review findings indicate that the addition of XG and HPMC to gluten‐free bread can enhance specific volume, sensory quality, and texture characteristics. The type of hydrocolloid, flour or starch used, water content, and the addition of various ingredients in the formulation influence the physical, textural, and nutritional properties of gluten‐free bread. The use of these hydrocolloids offers a solution for the food industry in producing high‐quality gluten‐free bread.
Introduction
Gluten‐free products are developing along with the increasing number of people with diseases related to gluten, such as wheat allergy, celiac disease, and non‐celiac gluten sensitivity (Brouns et al. 2013; Golley et al. 2014; Reilly 2016). People with celiac disease cannot consume products that contain gluten, as it may cause damage to the intestinal wall and interfere with the absorption of nutrients (Green and Cellier 2007; Harris 2011). Most bakery products are made from wheat flour, which contains gluten protein (Surono et al. 2017). The absence of gluten in bread results in low gluten‐free bread development volume (Muna et al. 2023). Gluten plays a role in protein‐starch interactions that give bread dough certain viscoelastic properties and in the stabilization and retention of gas cells during proofing and baking (Ahlborn et al. 2005). Therefore, it is necessary to use alternative ingredients that can replace the function of gluten in gluten‐free bread products.
Hydrocolloids are the most commonly used ingredient to replace gluten (Mir et al. 2016). Commonly used hydrocolloids in the food industry include agar, glucomannan, xanthan gum (XG), hydroxypropyl methylcellulose (HPMC), and pectin (Achmadi 2022). Their incorporation can modify the viscoelastic and rheological properties of dough, resulting in gluten‐free breads with characteristics that are more similar to those made with wheat flour. For example, certain hydrocolloids improve gas retention, moisture binding, and dough stability, which are crucial for bread structure and texture.
Among these, XG and HPMC are the two most commonly used and recognized hydrocolloids compared to other hydrocolloids (Crockett et al. 2011; Hager and Arendt 2013). This is because XG and HPMC are able to produce gluten‐free bread with superior and preferred characteristics. Their superiority lies in consistently producing bread with higher specific volume, softer crumb structure, and improved sensory acceptance compared to other hydrocolloids (Anton and Artfield 2008; Hager and Arendt 2013; Kang et al. 1997). This advantage has led to XG and HPMC becoming the primary focus of numerous studies, further reinforcing their importance in the food industry.
XG is an anionic polysaccharide that is commercially produced from a fermentation process by the bacterium Xanthomonas campestris . Structurally, XG consists of a cellulose‐like backbone of β‐(1 → 4)‐D‐glucose units with trisaccharide side chains containing mannose and glucuronic acid, which contribute to its high molecular weight and anionic character (Sworn 2009). These structural features give XG unique rheological properties, such as high viscosity at low concentrations, pseudoplastic (shear‐thinning) flow behavior, and stability over a wide range of pH and temperatures (Mohammadi et al. 2014). In general, XG produces bakery products with increased moisture and volume, higher crumb strength, improved texture, and moisture retention in dough and gluten‐free bread (Sworn 2009).
HPMC is the most commonly used type of hydrocolloid in the manufacture of gluten‐free bread (Crockett et al. 2011; Hager and Arendt 2013). This is because HPMC can produce bread with better specific volume characteristics, softer bread crumb, and superior sensory attributes (Barcenas and Rosell 2005; Guarda et al. 2004; Rosell et al. 2001). HPMC is a semi‐synthetic derivative of cellulose, obtained by substituting hydroxyl groups of the cellulose chain with methyl and hydroxypropyl groups (Li et al. 2013; Sarkar and Walker 1995). The cellulose backbone is typically sourced from wood pulp or cotton linters, making HPMC a plant‐derived hydrocolloid. Its physicochemical properties include water solubility, thermo‐gelling behavior (forming a gel upon heating and returning to solution upon cooling), and the ability to form stable films (Crockett et al. 2011; Hager and Arendt 2013). These properties are particularly advantageous in gluten‐free breadmaking, as HPMC provides viscoelasticity to dough, mimics the gas‐holding capacity of gluten, and produces loaves with higher specific volume, softer crumb texture, and superior sensory attributes (Barcenas and Rosell 2005; Guarda et al. 2004; Rosell et al. 2001).
Bread specific volume is one of the most important visual characteristics of bread products and is a key parameter observed when evaluating bread quality (Hager and Arendt 2013). Another important aspect of gluten‐free bread characteristics is texture. Consumers desire a soft and pliable texture, which is associated with low hardness values (Hager and Arendt 2013). Color is an important visual characteristic in food and is one of the aspects that influence consumer preferences and purchasing decisions. Calle et al. (2020) stated that the color parameter of bread is the first characteristic observed by consumers, thus determining consumer choice and preference. In terms of nutritional content, available gluten‐free products generally do not contain the necessary nutrients, both in quality and quantity, to maintain a balanced diet (Alencar et al. 2012).
This literature review synthesizes current evidence on the role of XG and HPMC in determining the physical properties, textural attributes, and nutritional quality of gluten‐free bread. Emphasis is placed on XG and HPMC as the most extensively applied hydrocolloids, whose effectiveness in improving the overall quality of gluten‐free formulations has been consistently demonstrated.
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