Prevention of Storage Aging in Dried Raw Blue Fox Skins

Abstract

Ninety dried raw blue fox skins having two different dietary backgrounds, saturated fat and fish fat feeding, were submitted to the following experimental treatments: dressing after pelting; control storage at 8 [ddot]C or at -20 [ddot]C; antioxidant diet, storage at 8 [ddot]C or at -20 [ddot]C; butylhydroxytoluene (BHT) drumming, storage at 8 [ddot]C or at -20 [ddot]C; nitrogen gas, storage at 20 [ddot]C; and pickling, storage at 8 [ddot]C. Each storage group contained five skins from both dietary groups. Storage duration for the dried raw skins was approximately one year, during which the changes in their fatty acid compositions were analysed. After the storage period the skins were dressed and the physical characteristics of the leathers were determined.

The dietary background of the animals had a significant influence on the fatty acid profiles of the dried raw skins, but it did not affect their fat peroxidation during storage. Moreover, freezing at a temperature of -20 [ddot]C or the antioxidant treatments employed did not prevent lipid peroxidation in the skins. In the pickle-treated skins the changes in the fatty acid profiles were even more pronounced than in the other groups. The only skins in which the fatty acid composition stayed constant were those stored in nitrogen gas.

The dietary background affected the breaking load and the elongation at break of the leather. Based on the measured physical characteristic of elongation at break, the quality of the leather decreased when the skins were stored in circumstances involving oxygen. The storage period is recommended to be kept to a minimum time, and storage temperatures above ±0 [ddot]C should be avoided, because of water condensation. The results also emphasize the importance of careful conservation and proper handling of the dried raw skins.     

Effect of dietary fat and lighting programme on broiler skin strength and elasticity related to skin tearing

Three trials were conducted to evaluate the influence of dietary fat and light programmes during rearing on skin quality of a total of 7800 broilers to resist plucking stress. Experimental treatments were two light programmes of light:dark hours in trials 1 (24:0 and 16:8) and 2 (21:3 and 16:8), and two dietary fat sources of animal fat (AF) and soy bean oil (SBO) in trial 3. Within each trial the broilers were reared in separate pens of each replicate (n = 4) in two similar houses. The total frequency of skin tears and downgraded skin tears caused by the plucking process were registered by visual examination of 325 broilers from each replicate after plucking, and all carcasses were weighed individually. Broilers with intact skin and with skin tears were removed from the slaughter line and after air chilling, breast skin samples with dermis and hypodermis were cut and used for skin tensile strength and elasticity measurement.

Light programmes with long dark periods during raising of broilers reduced skin tearing at the processing plant. The use of soy bean oil as dietary fat source in comparison with animal fat increased the skin tearing frequency (P = 0.066) and showed slightly reduced skin elasticity. Skin tears were more frequent among female broilers, and they had a lower skin tensile strength (P < 0.001) and elasticity (P < 0.01). An overall positive correlation between broiler weight and skin tears was found and a negative correlation between frequency of skin tears and breast skin elasticity was found for female broilers, whereas skin strength showed less connection to skin tear occurrence.     

Influence of malt roasting on the oxidative stability of sweet wort

Influence of malt roasting on the oxidative stability of sweet wort was evaluated based on radical intensity, volatile profile, content of transition metals (Fe and Cu) and thiols. Malt roasting had a large influence on the oxidative stability of sweet wort. Light sweet worts were more stable with low radical intensity, low Fe content, and ability to retain volatile compounds when heated. At mild roasting, the Fe content in the wort increased but remained close to constant with further roasting. Dark sweet worts were less stable with high radical intensities, high Fe content, and a decreased ability to retain volatiles. Results suggested that the Maillard reaction compounds formed during the roasting of malt are prooxidants in sweet wort. A thiol-removing capacity was observed in sweet wort, and it was gradually inhibited by malt roasting. It is possibly caused by thiol oxidizing enzymes present in the fresh malt.     

Effectiveness of different soil amendments to reduce the Pb and Zn extractability and plant uptake in soils contaminated by anticorrosion paints beneath pylons

Red lead (Pb₃O₄)‐ and ZnO‐containing anticorrosion paints in the past have been extensively applied to high‐voltage steel pylons which has led to heavy metal (HM) soil contaminations in their vicinity. Since pylons are commonly found on agricultural land, there is a potential risk of HM plant uptake. This is promoted by the fact that in contrast to the moderate total Pb contents (several 100 mg kg^–1) in three nutrient‐poor and acidic pylon soils the Pb amounts extractable with NH₄NO₃ were extremely high, reaching almost 20% of total Pb. A 18‐week field pot trial (three harvests in a six‐week interval) using Lolium multiflorum was conducted to study the HM plant uptake and the efficiency of the four soil additives, lime (LI), Novaphos (NP), water‐treatment sludge (WS), and ilmenite residue (IR) in reducing the plant uptake and NH₄NO₃‐extractability of Pb and Zn in the soils. Lead concentrations in L. multiflorum shoots grown in the untreated soils reached maximum values of 128 mg (kg dry weight)^–1. Novaphos was most efficient in decreasing shoot Pb (–90%) followed by LI (–78%) and WS (–73%). For Zn, too, LI (–82%), NP, and WS (both –66%) substantially reduced plant uptake. Ilmenite residue was generally only poorly efficient. The dry‐matter yield in the NP, LI, and WS treatments was significantly increased. While the relationship between Pb‐NH₄NO₃ and Pb‐plant was high when considering the three harvests separately (R > 0.93) a poor relationship (R = 0.63) exists over all harvests together. This was attributed to different transpiration rates affecting the HM flux into the plants, since the temperature regime changed greatly during the cultivation period. For Zn, no such close relationship between the NH₄NO₃‐extractable soil fraction and shoot Zn was found, most likely due to antagonistic effects from Mg which greatly varied in the three soils.     

Harvesting an invasive bivalve in a large natural lake: species recovery and impacts on native benthic macroinvertebrate community structure in Lake Tahoe,USA

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