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Infant Formulae: Ingredient Selection, Manufacturing Technology, Innovation, Challenges and Opportunities
Nicolas MALTERRE, Loreto M. ALONSO-MIRAVALLES and James A. O’MAHONY
School of Food and Nutritional Sciences, University College Cork, Ireland
1.1. Introduction
1.1.1. Context for formula-feeding
The Food and Agriculture Organization/World Health Organization (FAO/WHO) give the following definition for infant formula: “Infant formula means a breast-milk substitute specially manufactured to satisfy, by itself, the nutritional requirements of infants during the first months of life, up to the introduction of appropriate complementary feeding” (Joint WHO/FAO/UNU Expert Consultation 2007). In response, infant formulae are primarily designed to mimic the nutritional profile of human milk. While breast-feeding is exclusively recommended for the first six months of life, infant formulae provide a suitable alternative in specific situations where the mother cannot or does not want to breast-feed (Guo 2014). Indeed, the WHO advises that mothers of new-born babies should be informed of the benefits and superiority of breast-feeding. However, formula-feeding presents advantages, such as meeting specific nutritional requirements, convenience and flexibility. If formula-feeding is chosen over breast-feeding, recommendations are given regarding their compositions (section 1.2), based on the composition of human milk.
1.1.2. Human and bovine milk
The raw material most extensively used for decades for the production of infant formulae is bovine milk (Table 1.1; Blanchard et al. 2013). Consequently, a deep understanding of the composition of human milk is essential to most closely match the chemical composition and, increasingly, the nutrition and health outcomes of breast-fed babies (O’Mahony and Fox 2013; Crowley et al. 2016). At a macro level, the composition of human milk and infant formula can be considered as the macronutrients, proteins, lipids, carbohydrates and minor nutrients. The protein content and quality (i.e. digestibility and bioavailability) of infant formula is critical in influencing the growth and development of the infant (Blanchard et al. 2013). Protein in the formula will supply nitrogen and amino acids that are essential for the development of the infant. Bovine milk contains three times more protein than human milk, signifying that bovine milk-derived protein ingredients need to be recombined in ratios that will best match the protein content and profile of human milk, also considering the higher proportion of casein to whey (casein represents 80% of total protein for bovine milk compared to 40% for human milk), making raw bovine milk unsuitable for infants.
Table 1.1. Comparison of the composition of human milk and bovine milk
(data from Blanchard et al. (2013))
| Macro ingredients (per 100 ml) | Human milk | Bovine milk |
| Total protein (g) | 1.55 | 3.5 |
| α-Lactalbumin (g) | 0.35 | 0.2 |
| β-Lactoglobulin (g) | 0 | 0.35 |
| Immunoglobulin (g) | 0.15 | 0.05 |
| Linoleic acid (% fat) | 10 | 3 |
| Total carbohydrates (g) | 7.5 | 4.5 |
| Oligosaccharides (g) | 1.0 | Trace |
Beyond total protein content, another important aspect to consider is the quantity of each essential and semi-essential amino acid. In this regard, the FAO/WHO declare that, for an equal energy value, the formula must contain an available quantity of each essential and semi-essential amino acid at least equal to that contained in the reference protein (human milk, as defined in Table 1.2). Individual free amino acids may be added to infant formula, but only to improve its nutritional value for infants. Essential and semi-essential amino acids may be added to improve protein quality, but only in amounts necessary for that purpose (FAO 1981).
Table 1.2. Amino acid content of human and bovine milk protein
Another major macronutrient to consider in the formulation of infant nutritional products is lipids, which provide 40–50% of the daily energy intake. The lipid fraction of infant formula is usually incorporated in the form of blends of different vegetable oils in order to best match the fatty acid profile of human milk (Blanchard et al. 2013). Concerning carbohydrates, the main constituents of human milk and infant formula are oligosaccharides and lactose, and to best match human milk, significant fortification with lactose is needed in bovine milk-based formulae (for detailed information on the composition of infant formulae and the ingredients used, see section 1.3). It is also important to appreciate that while infant formulae are based on human milk composition, this knowledge base is continually developing and evolving, with new scientific information constantly becoming available (Hemmingway et al. 2020; Caldeo et al. 2021).
1.2. Types of infant formula and respective regulations
Foods for infants and young children collectively represent a wide range of products from birth to three years. These products may be divided into five major categories: first-age infant formula, second-age or follow-on formula, cereal-based and baby foods for infants and young children, young child formulae and formulae for special medical purposes. Each of these nutritional product categories is governed by different regulations, having different protein and amino acid requirements, among other important considerations such as carbohydrates, lipid content and classes, and concentrations of micronutrients such as minerals and vitamins (Table 1.3).
1.2.1. Infant or first-age formula
Infant milk, or first-age infant formula (0–6 months), is an industrially produced, highly formulated, nutritionally complete, human milk substitute, designed for infant consumption during the first months of life through to the introduction of appropriate complementary feeding (Koletzko et al. 2005; O’Callaghan et al. 2011). It is typically based on bovine or caprine milk and other ingredients (e.g. lipids, carbohydrates and minerals), which have been proven to be suitable for infant feeding. Infant formula attempts to mimic the nutritional profile of human breast milk and is the only food, other than human milk, that the medical community considers nutritionally acceptable when a mother cannot breast-feed or chooses not to breast-feed, or when the infant has some type of allergy/intolerance (Nasirpour et al. 2006; Thompkinson and Kharb 2007). Regarding the protein composition of infant formulae, bovine and caprine milk proteins (whey and caseins), soy proteins and their respective hydrolysates are permitted for the production of infant formulations (FAO 1981).
The protein content is typically between 13 and 15 g/l, and varies depending on the type and quality of the protein; for example, a minimum of 1.8 and a maximum of 2.5 g of protein per 100 kcal apply in the case of bovine and caprine milk-based formulae. On the contrary, infant formula manufactured from soy protein isolate...
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