Effective preservation of raw goat skins for the reduction of total dissolved solids
Abstract Raw hides and skins serve as the raw material for leather making industries. The main constituent of these raw materials is protein with about 70% of moisture and they are susceptible to microbial attack; it is essential to preserve the protein matrix of skin/hide before converting it into leather. Though the preservation of skin/hide by using common salt to an extent of 40–50% (w/w) is widely practised, this method generates a huge amount of pollution in the form of total dissolved solids (TDS) and chlorides (Cl) during leather processing. Therefore various investigating groups have been involved in alternative curing systems. With this view, an attempt has been made to evolve a less-salt (5% salt with sodium meta-bisulphate) and salt-less (sodium meta-bisulphate only) curing system for pollution abatement. The results obtained are discussed on the basis of TDS reduction, control of microbial population in the raw state during curing, changes in physical, biochemical, microbiological, thermal characteristics of the preserved skin and the mechanical properties of the leather made out of the experimental skins.
Effect of microbial activities on stored raw buffalo hide.
'Keeping qualities' of hides are dependent on the total microbial flora associated with the hides and the biochemical changes brought about by these microorganisms during short-term storage at ambient temperature (28 +/- 2 degrees C). It was evident that within first 24 hr of hide's ambient storage, bacterial load was raised to 8.8 log cfu g(-1) hide from 6.1 log cfu g(-1) hide. Nonlinear parabolic increase in release of hydroxyproline and tyrosine from stored hide was observed starting from 0 hr and confirming proteolytic activities. Continuous release of CO2 from the stored hide suggested its mineralization. Exponential release of free fatty acids during storage indicated simultaneous lipolysis. Thus the process of biodegradation during the course of ambient storage of hide piece was found to progress steadily and seems to be interrelated as well as very complex. During the storage period, the liquefaction of hide piece was also observed visually within 96 hr. Present studies of assessment of bacterial activities on hide with respect to total bacterial load, release of amino acids, free fatty acids and evolved CO2 provide data that can be used to formulate and evaluate hide curing agent(s) other than salt, thus rendering leather industry a platform to design bio-based technologies for efficient and ecofriendly preservation of raw materials.
Temperature effects on lily development rate and morphology from the visible bud stage until anthesis.
Day (DT) and night temperatures (NT) influenced Lilium longiflorum Thunb. 'Nellie White' stem elongation and development rate from the visible bud stage (VB) until anthesis. Plant height increase after VB was a function of the difference (DIF) between DT and NT (DT-NT). Plant height increased 90% as DIF increased from - 16 to 16C. A cubic model described bud development rate as a function of temperature from 14 to 30C. A linear model adequately described bud development rate as a function of average daily temperature from 14 to 21C. Based on the linear model, bud development rate increased 0.05 per day for each 1C increase in average daily temperature. The base temperature for bud development, i.e., the temperature at which bud development rate was 0, was calculated as 3.5C. Greenhouse forcing of vernalized Easter lilies is commonly divided into three phases: I) placement of vernalized bulbs in the greenhouse to flower initiation, II) flower initiation to VB, and III) VB to anthesis (De Hertogh and Wilkins, 1971). Plant morphological development differs during each of the forcing phases (De Hertogh and Wilkins, 1971). Growth during phase I is vegetative and consists of stem elongation and leaf expan- sion. Flower initiation, leaf expansion, and stem elongation oc- cur during phase II. Inflorescence expansion and stem elongation occur during phase III. Lily responses to temperature during phase III differed from those during phases I and II (Wang and Roberts, 1983). Lily development rate, quantified as days to unfold a leaf, is a de- creasing linear function of average daily temperature between 14 and 30C during phases I and II (Karlsson et al., 1988). Lily development rate during phase III is a nonlinear function of temperature (Healy and Wilkins, 1984). The effect of temper- ature on the rate of lily development decreases as DT and/or NT increase during phase III (Rob and Wilkins, 1973; Healy and Wilkins, 1984). Easter lily morphological development is thermomorpho- genie. For instance, internode length increases as the DIF be- tween DT and NT increases (Erwin et al., 1989). In addition, leaf orientation, leaf length, and flower length are also influ- enced by diurnal changes in temperature.