Phycocyanin. Shelf life and use as colorant in skin care

Abstract

Blágræna bakterían Arthrospira platensis eða Spirulina inniheldur blátt litarefni sem nefnist Phycocyanin. Þetta litarefni er mjög verðmætt þar sem náttúruleg blá litarefni sem hægt er að nota í mat og snyrtivörur eru mjög sjaldgæf. Á undanförnum árum hefur krafa frá neytendum aukist um að framleiðendur notist við náttúruleg litarefni bæði í matvæla- og snyrtivöruiðnaðinum. Markmið þessarar rannsóknar er að meta áhrif mismunandi hitastigs og rotvarnarefnisins sodium azid á geymsluþol Phycocyanin í vatnslausn og einnig áhrif mismunandi hitastiga á Phycocyanin í andlitsmaska. Niðurstöður sýndu að fyrstu 5 daga geymsluþolsmælinga voru vatnslausnirnar sem geymdar voru við stofuhita og innihéldu sodium azid stöðugri (k=0.013±0.002 dagar-1, t1/2= 53.6±9.6 dagar. R2=0.89) en lausnirnar sem geymdar voru við 6°C (k=0.029±0.007 dagar-1, t1/2= 25.2 ± 7.1 dagar. R2=0.86). Niðurbrot Phycocyanin var hægari eftir það og lausnin sem geymd var við 6°C var stöðugri (k=0.0015±0.0005 dagar-1, t1/2=502.3±143 dagar. R2=0.92) en lausnin við stofuhita (k=0.0018±0.0004 dagar-1, t1/2 =395.9±108.7 dagar R=0.93). Lausnirnar sem geymdar voru við stofuhita en innihéldu ekki sodium azid lyktuðu illa og voru gruggugar eftir dag 7 og geymsluþolsmælingum var hætt. Notkun rotvarnarefnisins sodium azid hægði á niðurbroti Phycocyanin í vatnslausn. Með tímanum varð litabreyting á öllum vatnssýnum og var hún það mikil að öll sýni fóru yfir þröskuldsgildi deltaE sem er 5.Sýni af andlitsmöskum voru geymd við stofuhita og 6°C. Eitt sýni úr hvorum hóp var myglað eftir 22 daga af geymslu. Liturinn á maskanum var stöðugri við 6°C, en litabreyting var undir þröskuldsgildi deltaE fyrir báða hópa þannig að litabreytingar voru rétt sýnilegar við dag 22. Maskinn hafði lengri geymsluþol en vatnslausnirnar sem ekki innihéldu sodium azid, mögulega vegna lægri vatnsvirkni.

The bluegreen microalgae Arthrospira platensis or Spirulina, contains a blue pigment protein named Phycocyanin. This pigment is highly valuable as natural blue colorants that have the potential to be used in food and skincare products are rare. The aim of this study was to evaluate the effects of different temperatures and the preservative sodium azid on shelf life of Phycocyanin in water solutions and the effect of different temperatures on the shelf life of Phycocyanin in a facial clay. Results showed that for the first 5 days of shelf life evaluations, water solutions that were stored at room temperature with sodium azide were more stable (k=0.013±0.002 days-1, t1/2=53.6±9.6 days. R2=0.89) than solutions at 6°C (k=0.029±0.007 days-1, t1/2=25.2 ± 7.1 days. R2=0.86). Rate of degradation was slower for both solutions after that and solutions stored at 6°C were more stable (k=0.0015±0.0005 days-1, t1/2=502.3±143 days. R2=0.92) than solutions at room temperature (k=0.0018±0.0004 days-1, t1/2=395.9±108.7 days. R=0.93). The solutions stored at room temperature without sodium azid had a foul smell and turbidity on day 7 and shelf life was deemed over. The use of the preservative resulted in a clear delay in the degradation process of Phycocyanin in water solutions. As for change in color, all samples exceeded deltaE threshold of 5 that indicates the onset of instability. Color difference in all samples was considered extremely remarkable.Clay samples were stored at room temperature and 6°C. One sample of each group had signs of mold on day 22 of storage. The color of the clay was more stable at 6°C, but both groups were under deltaE threshold of 5 and changes in color were just noticable on day 22. The clay did have longer shelf life than the water solutions without sodium azide, most likely because of lower water activity.