Cellulose Derived Hydrocolloids and Microcrystalline Cellulose
Cellulose derivatives cover the range of modified celluloses approved as food additives (Table 7.2). These are methyl cellulose E461 (MC) and hydroxypropyl methylcellulose E464 (HPMC), used for binding and shape retention, film formation and barrier properties, and avoidance of boil-out and bursting at higher temperatures; hydroxypropyl cellulose E463 (HPC), which presents good surface activity exploited in use of lower viscosity grades of toppings for whipping or dispensing from aerosol cans; methyl ethyl cellulose E465 (MEC), and sodium carboxymethyl cellulose E466 (CMC), for viscosity improvement. The raw material for modified celluloses is cellulose pulp, which in turn is produced from wood pulp from specified species or from cotton linters .
Table 7.2. Examples of applications of hydrocolloidal MCC in food products
|Application Functions/Benefits of MCC
||Functions/Benefits of MCC
|Mixes for power bars and candy bars
||Stabilizes the emulsion; suspends the solids; improves creaminess and pulpiness; adds opacity
|Batters and breadings
||Improves cling; reduces drying time; reduces fat absorption during frying; reduces sogginess if finished product is stored under heat lamps
||Adds creaminess; suspends the solids; stable under high temperature processing; adds opacity
||Controls moisture absorption; nonnutritive bulk filler
||Enhances the mouthfeel characteristics; mimics the mouthfeel of oil; stabilizes emulsions; suspends the solids; improves cling; opacifier
||Prevents boil-out during baking/heating (no leakage or rupture); improves texture and flavor release
||Stabilizes microwave sauces; reduces skinning on sauces held on steam table; helps keep fried foods crisp under heat lamps; reduces fat pick up during frying
|High fiber drinks
||Colloidal or powder
||Increases dietary fiber; adds body and creaminess; suspends solids
||Controls flow and moisture migration; imparts stability; increases creaminess
||Shear stability allows pumping without viscosity loss; stabilizes emulsions; improves cling; adds body and creaminess; prevents boil-out— imparts heat stability; adds opacity
|Ice cream, frozen desserts
||Controls the ice crystal growth: leads to smaller ice crystals; enhances the mouthfeel; improves creaminess and meltaway; replaces fat in low-fat recipes
FMC Corporation (2014) (Division formerly “FMC Biopolymer” now FMC Health and Nutrition) Cellulose Gel—product description, application guide, and recipes. http://www.fmcbiopolymer.com/Food/Ingredients/CelluloseGel/Introduction.aspx (accessed on 19 March 2014)
Microcrystalline cellulose (MCC) has been used for over 40 years to provide physical stability and texture modification in a wide variety of food applications. The purification process utilized to manufacture microcrystalline cellulose renders the polymer into a highly functional food ingredient. Refined pulpwood is most commonly used as the starting raw material for manufacturing MCC. The pulping process is utilized to remove lignin, polysaccharides, low molecular weight cellulosic material, and extractives. Strong mineral acid hydrolysis is employed to remove all amorphous cellulose portions of the fiber. Following the steps of neutralization, washing, and filtration, the purified microcrystalline cellulose wetcake is diluted in water, and spray-dried to provide large particulate (noncolloidal) MCC. Noncolloidal MCC products are useful in food as a source of fiber and bulk and may also be used as anticaking agents for oily substances such as shredded cheese. The MCC wetcake can also be subjected to a wet mechanical disintegration step prior to drying. In this process, the cellulose particles are separated to submicron size and co-dried with carboxymethylcellulose (CMC) or other functional hydrocolloids, for example, alginate and pectin. These are often referred to as colloidal grades of microcrystalline cellulose and represent the category of MCC products most commonly used in food applications as stabilizers and texture modifiers.
MCC can be used in virtually all food segments that require unique stabilization solutions or bulk filler properties to develop stable and palatable products. Properly utilized, MCC can provide heat stability in bakery applications and suspension of insoluble particulates in beverages. Other examples include fat and solids substitution in salad dressings and heat shock stability and texture enhancement in frozen desserts. Stabilizers can have a tendency to disrupt flavor release and interfere with processing efficiencies. Microcrystalline cellulose is known to impart clean flavor without masking desirable flavor profiles. Manufacturers also rely on the unique rheological properties of microcrystalline cellulose to assist in processing. The combined attributes of texture modification, physical stability, and processing advantages associated with MCC make it a versatile stabilization ingredient.
MCC products were developed to provide special functional properties for specific end uses. These functional properties include ice crystal control, texture modification, emulsion stabilization, heat and foam stability, suspension of solids, and fat replacement. When MCC/hydrocolloid grades are properly dispersed, the cellulose particulates and soluble hydrocolloid set up a network. It is the formation of this insoluble cellulose structural network that provides the functionality .
The modification of the functional properties of MCC, by coprocessing formulations with other hydrocolloids, has resulted in the discovery of several potentially useful MCC alloys, each offering special properties for specific uses: a colloidal MCC/CMC product (Avicel RT 1133) has the ability to meet the requirements of retort sterilization while minimizing total process time; an ultra fine MCC/CMC/CaCO3 composition, which is an effective suspending agent in calcium fortified milk, has been made by adding CaCO3 during coprocessing; MCC has also been coprocessed with high methoxyl pectin to provide colloidal MCC stabilization in low pH protein-based beverage systems; MCC/CMC formulation exhibits unique structural properties, that is, high degree of elasticity indicative of a well-dispersed and stable system. Because of this property, the MCC/CMC (Avicel BV-1518) provides effective low viscosity suspension in neutral beverages (calcium fortified milk, chocolate beverages). In addition to neutral pH beverages, other market opportunities include nondairy and dairy desserts (texture modification), aerated food systems (foam stability), low pH sauces and dressings (emulsion stability), squeezable mayonnaise (viscosity control), and UHT cooking cream (uniform shelf-life consistency without gelation).
Health and well-being are among the most important drivers of growth in applications of MCCs. A great variety of MCC and coprocessed MCC products (Avicel, Avicel Plus, Gelstar, Microquick, Novagel, Viscarin, Hobart, Kitchenaid, and Kenwood) are available, mainly marketed by FMC Corporation, Premark Feg LLC, Whirlpool Properties, Inc., and Kenwood Manufacturing LLC. In the United States, microcrystalline cellulose has GRAS status and has been used safely in foods for over 30 years. In Europe, microcrystalline cellulose is listed in Annex II of the Regulation (EC) No 1333/2008 of the European Parliament and of the Council of 16 December 2008 on food additives . It is approved as E460(i) in the list of Microcrystalline cellulose permitted emulsifiers, stabilizers, thickening, and gelling agents for use quantum satis, the level required to achieve a given technological benefit  (Table 7.2).