Optimisation of tennis string production from bovine intestine : a thesis presented in partial fulfilment of the requirements for the degree of Master in Technology at Massey University, Palmerston North, New Zealand
The collagen and elastin content of the beef thread samples ranged from between 47-70% and 1.2-2.5% respectively. Amino acid analysis showed that the collagen present was probably collagen Type I while the non-collagenous proteins predominantly were globulins with a small amount of albumins. Putative "strong" and "weak" batches of threads could not be differentiated on the basis of collagen content or mechanical properties such as ductility, ultimate tensile strength or Young's modulus. Treatment of "strong" or "weak" threads with three different processes, sodium carbonate, sodium carbonate/EDTA and sodium hydroxide, gave no significant differences in products The sodium carbonate/EDTA process can remove 31.9% of non-collagenous proteins over the three stages of the process. The shrinkage temperature and ductility were lowered while the ultimate tensile strength. Young's modulus and diameter are increased by the processing. Threads given three successive trypsin treatments had 47.4% (2% trypsin) and 36.2% (0.6% trypsin) of non-collagenous proteins had removed. Properties of the treated threads from this treatment gave similar trends to threads from the sodium carbonate/EDTA process except that enzyme treatment resulted smaller thread diameters. Moreover, when the treated threads from the second and third high concentration trypsin treatments were heated, they stretched rather than shrank. This phenomenon was unexpected and apparently has not been previously reported in the literature. On subjecting threads which had had three successive trypsin treatments to the sodium carbonate/EDTA process, the stretch temperature phenomenon was abolished and the normal shrinkage temperature property of collagen was restored. However, the shrinkage temperature of the thread from the integrated trypsin -sodium carbonate/EDTA process was significantly lower than that from the sodium carbonate/EDTA process alone. This integrated process does not affect the tensile strength properties, but the diameter of the treated threads using the higher trypsin rate is significantly smaller than the starting materials. However, threads from the integrated process using lower trypsin seemed to show a trend toward smaller diameters but this observation could not be shown to be statistically significant. It is suggested that two trypsin treatments integrated into a sodium carbonate/EDTA process could be an optimum process provided the smaller diameter trend of wet thread can translate into smaller diameter in dry string.