Protein hydrolysates guard against heat damage

 The worsening of hair sensory attributes and hair breakage increase caused by cuticle and cortex layers degradation, are amongst the long–term damages of heat hairstyling. The aim of the present study was to evaluate the potential use of two Kelisema’s protein hydrolysates derived from sesame seeds (Kelipro Sesame, INCI: Hydrolyzed Sesame Protein) and hemp seeds (Kelihemp, INCI: Hydrolyzed Cannabis Sativa Seed Extract) as hair heat protectants. Simulating a customer hair care practice, virgin hair tresses were pre-treated with protein hydrolysates aqueous solutions and subjected to repetitive thermal stress cycles using a straightening iron. Single-fibre tensile testing was performed to assess hair damage; dry-state hair break stress and hair diameter change were evaluated.

In order to get hairstyling results in line with the ever-evolving fashion trends, the use of heat styling devices such as straightening and curling irons has long become very popular among professionals and customers. These tools make use of high temperatures to create the desired style through a process that temporarily removes water from hair and changes the internal hydrogen bonding structure to anchor a new conformation; the style lasts until hair is re-wetted or when the hair fibre re-adsorbs water from the atmosphere. 

Several publications have studied the various effects of high temperatures on hair keratin thermal denaturation; some of them demonstrated that hair damage can arise at temperatures generally employed in commercial heat styling devices, even though temperatures remains well below hair keratin decomposition temperature.1 The most considerable observed effects are the formation of pores, voids, cracks and air bubbles in the hair cuticle and cortex; these damages involve protein denaturation and can greatly affect hair’s physical and mechanical properties, water absorption and desorption profiles and hair strength.2,3 The degradation of the cuticle and cortex layers leads to rough and fragile hair resulting in an increase of hair breakage when subjected to combing;4 conceivably, damaged hair is also more likely to be prone to the negative effects of certain weather conditions and hair treatments.