**Abstract**

Originally hailing from Latin America, dulce de leche (DL) is one of the most widely manufactured dairy products in South America, where it is marketed as a paste or bar. Due to DL's low moisture content, the product can be safely stored at room temperature, which facilitates storage and transportation logistics. The primary ingredients used to manufacture DL are milk, sucrose, and an acidity reducer. Needless to say, the raw materials must be of good quality from reliable suppliers in order for the final product to have the desired characteristics. The milk used to make DL must be microbiologically safe, remain stable during thermal processing, and preferably exhibit a high solid content. Dulce de leche is defined as a product made with or without the addition of other food substances that is obtained from milk or reconstituted milk and added sucrose (either partially substituted or not by monosaccharides and/or other disaccharides) via concentration and heat action at normal or reduced pressure. This chapter aims to explore the chemistry, processing technology, and most common industrial practices for manufacturing DL in South America.

**Keywords:** dairy products, Maillard reaction, milk, evaporation, manufacturing technology

### **1. Introduction**

Dulce de leche (DL) is a dairy product that has widespread success and acceptance due to its pleasant sensorial characteristics. Nutritionally, it has a high energetic value and boasts high concentration of proteins, minerals, and carbohydrates.

During the manufacturing process, DL is submitted to high temperatures for long periods. This, along with the types of ingredients used in its formulation, stimulates an acceleration of the Maillard reaction rate and consequently an increase of 5-hydroxymethylfurfural index. The latter corresponds to one of the indicators used to verify the intensity of the heat treatment.

DL is formulated in plants that range from small, artisanal plants to small, medium, and large industrial dairy factories. The quality of the raw material, the type of formulation used, and the technology hurdles related to a lack of standardization of time and temperature during the manufacturing process have made it difficult for brands on the Brazilian market to be standardized.

It is therefore imperative to analyze, study, and prioritize how the different ingredients, manufacturing technologies, and heat treatment intensities influence the quality and uniformity of the product. Moreover, the lack of technical and scientific literature on this product underscores the need for further studies in the domain.
