An enzyme treatment process for the pre-tanning of sheepskins has been previously reported by the Leather and Shoe Research Association of New Zealand (LASRA) as an alternative to current industry operations. The newly developed process had marked benefits over conventional processing in terms of a lowered energy usage (73%), processing time (47%) as well as water use (49%), but had been developed as a “proof of principle’’. The objective of this work was to develop the process further to a stage ready for adoption by industry. A process ready for adoption by industry is one that is able to generate good quality products (good quality products are those that has solids removed to industry standards, without visible damages to grain surface, evenly dyed etc.), require minimal changes to plant or operation layout and reduce usage of resources (e.g. water and chemicals). Mass balancing was used to investigate potential modifications for the process based on the understanding developed from a detailed analysis of preliminary design trials. Results showed that a configuration utilising a 2 stage counter-current system for the washing stages and segregation and recycling of enzyme float prior to dilution in the neutralization stage was a significant improvement. Benefits over conventional processing include a reduction of residual TDS by 50% at the washing stages and 70% savings on water use overall. Benefits over the un-optimized LASRA process are reduction of solids in product after enzyme treatment and neutralization stages by 30%, additional water savings of 21%, as well as 10% savings of enzyme usage. The optimized (new) LASRA process uses existing equipment and requires no additional outlay of capital. The process is now developed to a point where it should be trialled at industrial scale.

Content: Sheepskin, a by-product of the meat industry, is then often processed to leather, primarily for the clothing industry. Where the tanneries are distant from the abattoirs and freezing works, the raw skins have to be transported long distances to be processed. In warm weather, there is the potential for putrefaction of the skins which then have to be disposed of at a cost. Depilation, the first step of leather processing, is designed to remove the wool from the skin without damaging it. Conventional depilation involves the use of strong alkali and sulfides, that are harmful to both the environment and the personnel carrying out the process due to the potential production of hydrogen sulfide, a toxic, flammable gas. To solve this problem, scientists have been looking to depilate skins using enzymes as these are environmentally friendly. Various enzymes, such as collagenase, keratinase, protease and lipase have been shown to be able to remove hair from skin, but unfortunately usually damage it. Furthermore, at present, they are not cost effective at an industrial level. We have found a simple solution, a derivative of a dairy by-product, that prevents putrefaction, preserving the skin for days at room temperature. In addition, it allows easy removal of the wool from the skin. Scanning electron microscopy showed there was no obvious damage to the surface of the depilated skin and that the wool is cleanly removed from the hair follicle. To assess any less visible damage that may have occurred as a result of soaking the skin, biochemical analyses were carried out to measure the changes to the amino acid composition, collagen crosslinks and proteoglycan concentrations of the depilated skins. Sheepskin depilated with this method was processed to leather and its physical properties such as tear, and tensile strength analysed. Culture dependent methods were used to isolate the microorganisms present in the solution after depilation, showed that only four main species were consistently found in the depilation fluid and on the skins. Metagenomic analysis, confirmed these findings and was used to follow the changes in the microbiome during the course of depilation. This presentation will describe the progress that has been made to understand the science behind these observations and compare the properties of skins depilated using this method with those depilated using the traditional beamhouse process. Take-Away: We are using a natural product to depilate sheepskin. The sheepskin is also preserved while depilation. Microscopy, chemical analyses, physical tests, and metagenomics analysis were done to understand the process.

This thesis consists of three essays that examine issues on university attendance behavior, factorsof university completion, and the labor market value of a university diploma in Sweden. Essay [I] analyzes how the rapid expansion of higher education that increased the geographicalaccessibility to higher education in the 1990s affected university enrollment decisions amongvarious socioeconomic groups of young adults in Sweden. The empirical findings show that theprobability of enrollment in university education increases with accessibility to universityeducation. The results also indicate that accessibility adds to the likelihood of attending auniversity within the region of residence. Access to higher education more locally seems to havedecreased the social distance to higher education, meaning that the option of attending highereducation, as compared to entering the local labor market after upper secondary school, hasbecome a more common and a more natural alternative for more socioeconomic groups insociety. Essay [II] compares the performance of students in universities built before and after the largedecentralization and expansion of the higher educational system in Sweden, starting in the late1970s. Two outcome measures are used: (i) whether or not the student has obtained a degreewithin seven years after she initiated her studies; and (ii) whether or not she obtained 120 creditpoints (the requirement for most undergraduate degrees) within seven years. Controlling forseveral background variables as well as GPA scores in a binomial probit model, we show thatstudents at old universities are about 5 percentage points more likely to get a degree and about 9percentage points more likely to obtain 120 credit points. However, in an extended bivariatemodel where we consider selection on unobservables into university type, we cannot reject thepossibility of no difference in performance between the two university types. Essay [III] analyzes the labor market value of a university diploma (sheepskin) in Sweden. Incontrast to previous studies, this study only focuses on Swedish university students who havethree years of full time university education or more − where some have obtained a universitydegree, others not. The results show that for male students, the wage premium of possessing adegree, i.e. the sheepskin effect, is roughly 5-8 percent. For women, it is about 6-7 percent forthose who have completed four years of fulltime or more. For students who attended a moreprestigious university in the metropolitan areas in Sweden and majored in the natural sciences, asheepskin effect of roughly 13 percent for men and 22 percent for women is traced. However,this result did not hold among students who attended. Keywords: Higher education, university enrollment; university choice; accessibility; universitycompletion; selection bias; propensity score matching, sheepskin, human capital.