Achieving Nutritional Quality & Functionality in RTD/RTF Formulas [Ingredients]

Originally Published: April 13, 2021
Last Updated: November 29, 2021
Achieving Nutritional Quality & Functionality in RTD/RTF Formulas [Ingredients]

In a webinar titled “Protein Ready-to-Drink Formulation Tips,” presenters focused on the importance of achieving nutritional quality & functionality in RTD/RTF formulas, with a focus on enteral types. Recent developments in reduced-mineral milk protein concentrate (MPC) and reduced-mineral milk protein isolate (MPI) enable enteral product formulators to achieve a high degree of nutritional product quality and functionality. Webinar presenters included David Clark, Ph.D., Owner and Managing Director, Bovina Mountain Consulting, LLC and Chenchaiah Marella, Ph.D., V.P. Research & Product Development, Idaho Milk Products.Ingredient R&D Application logo

Yet, what is an enteral formula? These products encompass part of the medical nutrition market at $14 billion, globally. Enteral formulas are consumed orally or via a nasal-gastric tube. “Enteral Products need to pack a significant nutritional punch in a small volume,” said Clark. Challenges do exist with these formulas including inconsistent regulatory terminology and definitions; determination of whether an infant is defined as a 6- vs a 12-month-old; whether the product is for general nutrition use or disease specific and/or designed for total or supplemental nutrition; and the existence of multiple distribution channels.

In addition to the challenges noted above, different diseases require distinct nutritional and physical properties. For instance, a product developed for dysphagia (difficulty swallowing) must be nutrient dense and low in viscosity. Protein quality and low phosphorous are important for an enteral formula designed for renal disease.

Continuing with the renal disease narrative, Clark provided an example of the dietary requirements of a 70kg man whose DRI of protein per day increased from 56g to 77-105g when on hemodialysis. The nutritional supplement developed for such a condition must prevent a buildup of Na, K, Mg and P. Phosphorous retention poses a serious problem, in particular, with the RDI for hemodialysis patients at 800-1000mg/d. While MPC/MPI provide among the highest quality protein, they are also high in phosphorous.

“High protein requires a tradeoff to control phosphorous levels (for a renal patient),” explained Clark. Previously, high protein enteral formulas required mixing MPC/MPI with caseinate or SPI to reduce phosphorous levels. “That used to be the end of the story until recent developments with reduced-mineral MPC/MPI were introduced to the market,” added Clark.

Formulation & Processing of Enteral Formulas with Reduced-Mineral MPC/MPI

In the production of reduced-mineral MPCs/MPIs, careful control of raw materials is critical, as they impact taste, solubility and shelflife. Ingredient interaction can be a potential pitfall in a complex mixture of ingredients. Sequence of ingredient addition and proper hydration of molecular ingredients (i.e., proteins and polysaccharides) can affect solubility vs insolubility.

Processing factors, such as heat that causes whey protein denaturation, can increase risk of aggregation and gelation. Homogenization is an important step in preventing such aggregation. Also, a stable monodisperse emulsion rather than a polydisperse emulsion will achieve stability, thereby preventing aggregation, noted Clark. A pH drop (controlled by adding buffer salts) and calcium leaching and crosslinking (controlled by adding a Ca-chelator or using reduced-Ca MPC/MPI) can cause sedimentation, gelation and phase separation during distribution and storage.

Achieving Nutritional Quality & Functionality in RTD/RTF Formulas (13:35% protein content RTD formula)

Multiple interacting factors contribute to RTD stability and instability. In most cases the optimum sits at the tip of a bell curve but each formula has a different ‘sweet spots.’ [17: 35% protein content RTD formula]

Formulators should use an MPC/MPI produced from the freshest milk with minimal heat treatment. Idaho Milk Products uses cold nanofiltration rather than evaporation to minimize heat treatment, said Marella. The level of denatured whey is an indicator of the amount of heat the MPC was exposed to during manufacturing, he added. Thermophilic spore content should be minimized to prevent spoilage over time.

Faster dispersion of the MPC/MPI improves solubility, decreases hydration time and has the potential to increase plant throughput during production of the finished formula. Improved heat stability of ready-to-drink (RTD) products reduces fouling of heat exchangers, resulting in fewer plant cleanups, explained Marella. And, MPC should have acceptable sensory profiles, exhibiting sweet aromatic, cooked/milky characteristics, while avoiding intense aromas and aftertastes, as well as grass/hay, tortilla and cardboard notes.

Multiple interacting factors contribute to the stability (or instability) of each enteral formula. In most cases the optimum ‘sweet spot’ sits at the tip of a bell curve, but each formula has different ‘sweet spots,’ noted Clark. ‘Sweet spots’ can be measured for criteria such as pH, Ca-chelator, buffering agents, MPC solubility, free calcium, heat stability and emulsifying properties, among others.

“We have gums, stabilizers, buffering salts, Ca-chelating salts and even calcium that comes from the MPC (in an enteral formulation). All these ingredients will have their own (optimum) functionalities. Also, when they are present together there will be interactions among these ingredients that could change the (best possible outcomes). It’s important to find the ‘sweet spot’ for each individual ingredient as well as when the ingredients are present together. This is possible only by doing testing, testing and more testing,” emphasized Marella.

Analytical tools are available for assessing the ‘sweet spot.’ Instrumentation can measure shelflife stability, gelation, solubility and phase separation. Marella stressed the importance of having a miniature version of a direct steam injection UHT processor to meet the requirement of testing. Another example of analytical testing involves a piece of equipment called a ZetaSizer. Particle size analysis at different time points gives an indication of micellar aggregation leading to gelation or phase separation, explained Marella.

MPCs with new functionality such as calcium-reduced Idaho Milk Products’ IdaPlus 1085 offer new nutritional and enhanced stability opportunities including extended shelf-life possibilities due to Ca reduction; higher total protein content, highest protein quality score & reduced phosphorus for renal formulas; reduction or elimination of chelators for clean label products; and low viscosity in beverages.

Marella cautions that the product developer needs to specify the type of application being developed so that an MPC/MPI with the proper functionality can be recommended. In the end, “finding those ‘sweet spots’ in an enteral formula requires the best and most consistent ingredients and testing, testing and more testing,” added Clark.

Click here to view the webinar “Protein Ready-to-Drink Formulation Tips”:

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