HAIR TREATMENT 177
Protein hydrolysates guard against heat damage
S. Mancon, A. Mondelli – Kelisema srl, Italy
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
Abstract
The prolonged use of heat styling devices may lead to cumulative effects on the hair fibre. These involve various physical and chemical changes of hair cuticle and cortex structure that seem significantly linked to a gradual protein thermal denaturation after exposure to high temperatures. 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.
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 Control Kelihemp Kelipro Sesame
20 15 10 5 0
-5
-10 -15 -20
* x500 passes
Figure 1: Hair diameter change. Data are reported as % change respect to virgin – hair. * Statistically significant vs virgin – hair (p < 0.05).
April 2018 * *
also more likely to be prone to the negative effects of certain weather conditions and hair treatments. Heat hairstyling gives hair the desired set and confers a high level of shine and smoothness; these short-term benefits seem to be greatly appreciated by consumers even though the repeated routine of heat-styling can lead to the cumulative effects described above. As a result, an ever-growing customer demand of specific ‘heat protectants’ hair care products has emerged and led manufacturers to an increased necessity of realising such products in order to meet these new requirements. From a scientific point of view, the concept of heat protection implies the moderating of temperatures which is somehow unlikely because heat is necessary for the styling, or the minimising of hair structure damage. Heat-damaged hair can be protected from additional insults and damages by providing an appropriate conditioning in order to reduce friction and eventually breakage; in this case, heat-damaged hair can greatly benefit from the use of specific conditioning products.
Another practicable way is to try ensuring hair surface protection, as far as possible, pre-treating hair with selected actives before thermal stress, in order to maintain cuticle integrity and protect cortex proteins from thermal damage.
PERSONAL CARE EUROPE
% hair diameter change
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