Evaluation of the Light Deterioration in Hair for Quality

Transcription

1 Evaluation of the Light Deterioration in Hair for Quality Examination of Mink Fur Products Mariko TERASHIMA, Keiji YOSHIMURA, Tetsuo IMAI, Daiki HOZAN, Yasuhiro ISHII1 and Kunio SHIRAI1 Tokyo Metropolitan Leather Technology Center, Sumida-ku, Tokyo , Japan Scleroprotein and Leather Research Institute, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu-shi , Japan (Received July 25, 2000; Accepted October 31, 2000) Abstract Light deterioration of hair in mink fur was evaluated by sensory evaluation, color difference measurement, scanning electron microscope (SEM) observation, fourier transform infrared (FTIR) measurement and chemical analysis of extracted protein, aiming to have an insight into the practical aspect of quality examination by summarizing these evaluation. As a result of the sensory test on the deterioration of hair in irradiated mink fur, deterioration in smoothness and straightness of guard hair was recognized within the irradiation time of 96h. In instrumental examination, a significant deterioration was detected in color difference, SEM picture, FTIR spectrum and analyses of extracted proteins within the irradiation time of 96h. The degree of deterioration detected was generally proportional to the irradiation time. It was recognized that examination items adopted in this study were meaningful for the evaluation of light deterioration of hair in mink fur. Furthermore, the introduction of FTIR measurement and chemical analyses of extracted proteins enabled to detect such a light deterioration that can't be detected by sensory test. Animal Scicence Journal 72 (1): 39-45, 2001 Key words: Mink hair, Xenon arc irradiation, Light deterioration Fur products have become one of the popular clothing materials in recent years. In particular, that from mink cultivated in Japan is one of the representative clothing materials. Although the market circulation of fur product increased, there is no quality standard well agreed socially. Consequently, such a popularization of furs has called a considerable number of consumer complaints involving the quality deterioration of hair. In case of mink fur, the majority of complaints involves light deterioration of hair. Light deterioration of hair has been mainly studied in connection with yellowing of wool, and there has been no report on the general quality deterioration by light exposure. The authors have been investigating on the evaluation method of light deterioration in mink hair. As a Corresponding: Mariko TERASHIMA (fax:+81 (0) ) Anim, Sci. J. 72 (1): 39-45, result, we have proposed deterioration indices of light induced oxidative products including cysteic acid residue in hair protein as estimated by FTIR microspectroscopy4), and of mechanical property and morphological change in the hair surface condition7). Furthermore, we inquired into the composition of distinct species of hair proteins extracted from mink hair by reduction with thiol compound5, 6), and reported that such an extractable protein characterization can provide measures for evaluating the light deterioration of hair keratin. The present study was done to assess the validity of these techniques in practical application to the fur quality examination. Cut specimens of mink fur were irradiated under the condition to mimic the practical use, and the deterioration of specimen was

2 TERASHIMA, YOSHIMURA, IMAI, HOZAN, ISHII and SHIRAI Fig. 1. Sampling portion of sapphire mink fur. evaluated by sensory examination, color difference measurement, SEM observation, FTIR measurement and analyses of extracted proteins to distinguish their characters in view of the practical assay of fur quality. Materials and Methods Mink fur sample Sixteen pieces of tanned sapphire mink (male, 0 size) prepared as a lot of ordinary market product were used. The main part was cut into portions of a Xenon arc irradiation Specimens condition of b-1, b-2, c-1 and c-2 in Fig. 1 were used for the irradiation experiment. A specimen was irradiated in a fade meter (Atlas Electric Devices Co., Ci 3000) pasted on cardboard with hair side up. Xenon arc was applied at a black panel temperature intensity of 1.20kJ/m2 (420nm). The irradiation time was 1, 6, 12, 24, 48, 72 or 96h. For each irradiation time, 4 specimens from 4 different mink furs were used to give a 4 times repeated experiment. Analyses and examinations of irradiated specimen Sensory examination: Three of the examiners having a professional experience for longer than 30 Anim. Sci. J. 72 (1): 39-45, of years examined the quality of irradiated specimens by sensory test. An irradiated specimen was examined in comparison with the unirradiated counter specimen of the opposite position across the back bone, as shown in Fig. 1. The quality was graded 1 (poorer) to 5 (better) in respect with such evaluation items, as smoothness, straightness (no deformation of hair axes like inflection), and stiffness of guard hair, density of underfur coat, handle of underfur and color. These evaluation items are generally adopted in the fur trade business. a*, b*) of hair side between the specimens before and after irradiation was measured on color meter (Suga Inc, MS2 type). The specimen, after adjusting the orientation of hair axis, was put in a transparent polyethylene bag and color difference was measured. The oppositely positioned counter specimen was used as the unirradiated control. For each specimen, the measurement was done at 2 positions near the backbone line and belly part. A mean of 16 measured values was calculated for each irradiation time. SEM observation: Guard hair strings separated from underfur were cut at the root using razor from an irradiated specimen and examined under SEM (Hitachi Inc., S-3500 N). The hair surface condition at the tip portion was evaluated as described in the previous paper7). FTIR measurement: Guard hair string picked from irradiated specimen as described earlier in SEM was used for FTIR examination. An absorbance spectrum was measured by attaching ATR (ATR-VZ, ZnSe prism) to the microsampling FTIR spectrometer (JASCO Corporation, MFT-2000) by reflection mode, as described in the previous paper4). For every irradiation condition, 18 strings of hair were measured. The differential absorbance spectrum between specimens before and after irradiation was taken in a in the previous paper4). Ratios of peak height at 1,194cm-1, peak height at 1,040cm-1 and these peak area against amide III peak height and area were obtained. As the peak wasn't recognized in differential spectrum for one hour-irradiated hair, 10 spectra

3 Evaluation of Deterioration in Mink Hair Extraction of proteins 1. Alkali extraction: Portions of guard hair that grows above the underfur coat were cut with scissors and used for the extraction of protein. A portion of hair was extracted in accordance with DIN ). Thirty mg of hair was stirred with 3ml of O.1N sodium hydroxide aqueous solution in a test tube with min. The quantity of extracted proteins was determined by micro-biuret method2). Two ml of the extract and 1ml of biuret reagent were mixed, and the absorbance at 310nm was measured. The calibration curve was made using a mink hair protein preparation by the S-sulfonation procedure described later. A portion of the extract for intact and 96 h- irradiated hairs, was dialyzed against distilled water at tein. Size exclusion chromatography (SEC) was performed using Waters 650 Protein System. A column set connected in series (Superdex 75 HR 10/ 30 and Superdex Peptide HR 10/30) was used with a flow rate of 0.5ml/min using a buffer containing 0.05 M Tris-HCl at ph 7 at room temperature. The eluate was monitored by the absorbance at 230nm. 2. Extraction by s-sulfonation: Another portion of guard hair was subjected to the extraction by s-sulfonation6). The extracted protein was characterized by sodium dodecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE) as described in the previous paper6). Results and Discussion Evaluation of light deterioration by sensory examination Although the graded value for a specimen of a given irradiation time varied considerably depending on the individual examiner, they revealed, that the longer the irradiation time was the poorer the graded value of specimen. Hence first of all the minimum irradiation time for a given examiner to grade, the irradiated specimen as unambiguously poorer than the unirradiated control, was recorded and then the range of the minimum irradiation time for 3 examiners was reported in Table 1. All the three examiners graded the color of 1 h-irradiated specimen poorer than grade 3. On the other hand, for the density of underfur coat, none of the three examiners detected deterioration after 96h irradiation. However, for other checkpoints a certain deterioration on 1 h- to 96 h- irradiated specimen was detected by all the three examiners with a certain variation among the examiners. Taking into consideration that all the examiners have a professional experience for longer than 30 years, it is reasonable to judge that the irradiation condition adopted in the present experiment is mild and, at least, not unrealistically drastic and hence its Table 1. Irradiation time until detection of deterioration by sensory evaluation Fig. 2. Color difference between before and after irradiation. Bars represent standard deviation of sixteen measurements. Anim. Sci. J. 72 (1): 39-45,

4 TERASHIMA, YOSHIMURA, IMAI, HOZAN, ISHII and SHIRAI Fig. 3. Surface structure of intact and irradiated guard hair by scanning electron microscope (SEM). (a) intact, (b) 12h irradiated, (c) 24h irradiated, (d) 96h irradiated result can have the valid relationship with the market trade criteria. Color change after irradiation As shown in Fig. 2, the color change of hair by E* between intact and 96 h-irradiated specimen was 7.02 (standard deviation 0.89), consisting of a small (=6.76, standard deviation 0.94). This indicates a for 1 h-irradiated specimen means that the detectability of deterioration by the instrumental method is equal to sensory evaluation, as seen in Table 1. Evaluation of deterioration on hair surface by SEM Scanning electron microscope (SEM) on hair from the irradiated fur specimen demonstrated the melting of scale structure for the hair irradiated for not longer than 24h, and the extensive melting of surface structure for that irradiated for 96h (Fig. 3). Consequently, SEM examination is valid to evaluate the Anim. Sci. J. 72 (1): 39-45, Fig. 4. Effect of irradiation time on cysteic acid peak height in fourier transform infrared (FTIR) spectrum. Bars represent standard deviation of ten measurements.

5 Evaluation of Deterioration in Mink Hair Fig. 5. Yield of soluble proteins extracted with 0.1N sodium hydroxide solution against irradiation time. deterioration of hair irradiated for longer than 24h. Such a hair surface deterioration observed by SEM presents a supporting evidence for the sensory examination of smoothness and straightness of hair as reported in Table 1, because a certain deterioration was detected within the irradiation time of 96h by the sensory examination for the both check points. Cysteic acid determination by FTIR With increasing irradiation time, cysteic acid peaks originated from cystine residues appeared to be distinct at 1,194cm-1 and 1,040cm-1 on the difference spectra, same as in the previous paper4). Figure 4 shows plots of 1,040cm-1 peak height ratio against the irradiation time. Peak height ratio at 1,040cm-1 increased clearly in proportion to the irradiation time as in the previous study4). Similar results were obtained for 1,192cm-1 peak height ratio and the summed area ratio of the both peaks at 1,040cm-1 and 1,192cm-1. The present FTIR method therefore can provide a measure for the quantitative evaluation of deterioration on fur product. Furthermore the present FTIR data presents an objective base to the validity of sensory evaluation, since a certain deterioration in the surface structure of 1 to 96 h-irradiated guard hair is also detected by the present sensory test (smoothness and straightness of guard hair). Property of extracted protein Fig. 6. Size exclusion chromatography (SEC) of 0.1N sodium hydroxide extract. (a) intact, (b) 96h irradiated Arrow indicates the elution time of bovine serum albumin (BSA). Fig. 7. Yield of soluble proteins extracted as s-sulfonate derivative against irradiation time. Anim. Sci. J. 72 (1): 39-45,

6 TERASHIMA, YOSHIMURA, IMAI, HOZAN, ISHII and SHIRAI Fig. 8. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of extracted s-sulfonate derivative from intact and irradiated hair. H, L: molecular weight standards 1: intact 5: 24h irradiated 2: 1h irradiated 6: 48h irradiated 3: 6h irradiated 7: 72h irradiated 4: 12h irradiated 8: 96h irradiated The extractability of guard hair protein with 0.1N sodium hydroxide solution rose linearly with increasing irradiation time up to an extracted protein amount of about 9% (Fig. 5). Size exclusion chromatography (SEC) of the extracted protein of 0 h-irradiated hair indicated a minor but distinct peak in a region earlier than BSA (Fig. 6). In contrast to this, 96h irradiated hair indicated a prominent peak at the same position. Proteins with such a large size have been rendered soluble by 96h-irradiation. Consequently, at least a part of hair protein undoubtedly receives a partial fragmentation during irradiation and becomes alkali-soluble protein. Since the increase in alkali extracted protein by irradiation parallels the increase in cysteic acid residue as determined by FTIR, an oxidative breaking of SS crosslinkage of keratin is probably involved in the extractability increase. The relation between the extractability of protein with thiol reduction/s-sulfonation and the irradiation time demonstrated a quite different pattern (Fig. 7). It indicated a sudden decrease in the extractability from 62% to 26% in an irradiation time from one to 6h. In an irradiation time from 48 to 96h, the extractability maintained almost constant. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the extracted protein from intact kda region, assignable to microfibril proteins3). Anim. Sci. J. 72 (1): 39-45, These bands were weakened more and more with increasing irradiation time, and become undetectable cause of the decrease in protein extractability is therefore considered as the conversion of a part of SS crosslinkages in microfibril protein to thiol resistant crosslinkages or the generation of additional crosslinkages resistant to thiol reduction. Summarizing the results of protein extraction experiment, two types of protein degradation occur during the irradiation of hair. One is the generation of thiol resistant intermolecular crosslinkages and the other is the oxidative cleavage of intermolecular crosslinkages. The former type of protein degradation can provide an index of fur quality specifically in the early stage of deterioration whereas the latter can provide a general index of quality deterioration that takes place cumulatively in a long range of time scale. Consequently, the examination items adopted in the present study are considered to be valid in the quality evaluation of light-exposed mink fur product. Furthermore, especially the present methods of FTIR and guard hair protein extraction are even more sensitive to an early stage of deterioration than the conventional sensory evaluation. On the other hand, different instrumental examination detects different phase of quality deterioration of fur. Thus, the yellowing of hair measured by color meter is an index of the earliest phase of light deterioration. The second phase of deterioration can be assessed by the protein insolubilization and its composition change during light exposure. The third phase of deterioration which accumulates for a long time span can be assessed by the oxidative cleavage of SS crosslinkages as estimated from the cysteic acid determination by FTIR or the protein extraction with alkali. SEM technique is suitable for detecting a rather advanced phase of deterioration. References 1) DIN , Bestimmung der AlkalilOslichkeit von Wolle. Deutsches Institut fur Normung. Berlin ) Itzhaki RF, Gill DM. A Micro-biuret method for estimating proteins. Analytical Biochemistry, 9:

7 Evaluation of Deterioration in Mink Hair 3) Kamal AMS, Nomura Y, Ishii Y, Shirai K. Properties of bovine hair keratins solubilized with thioglycolate. The Journal of The American Leather Chemists Association, 93: ) Terashima M, Imai T, Chonan Y, Shirai K. Evaluation of the deterioration in mink hair under xenon arc irradiation by fourier transform infrared (FTIR) microspectroscopy. Sen'i Gakkaishi, 54: ) Terashima M, Imai T, Chonan Y, Shirai K. Effect of xenon arc irradiation on mink hair protein extracted with thioglycolate. Animal Science Journal, 70: ) Terashima M, Yoshimura K, Imai T, Hozan D, Shirai K. Properties of protein extracted as s- sulfonate derivative from irradiated mink hair. Animal Science Journal, 71: ) Terashima M, Yoshimura K, Imai T, Hozan D, Shirai K. Evaluation of the deterioration in mink hair under xenon arc irradiation by mechanical measurement and morphological observation. Sen'i Gakkaishi, 56: Anim. Sci. J. 72 (1): 39-45,