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The aim of this study was to evaluate the physicochemical composition and gelatin properties of collagen hydrolysates obtained from chicken bones under different heat treatment temperatures (50, 70 and 90°C) and times (30, 60 and 90 min). Results showed that heat temperature can significantly improve the solubility of protein (from 37.8 to 72.1%). Degree of hydrolysis and SDS-PAGE analysis showed that the mean molecular weight of collagen hydrolysates at 50 and 70°C were higher than that of hydrolysates at 90°C, which indicating that the triple-helix structure of protein transmitted to chains and subsequently form protein-protein linkages during heating. FTIR analysis demonstrated that the relative content of β-sheet decreased and random coil increased significantly (P < 0.05), whereas α-helix and β-turn had no significant changes during heating treatment (P > 0.05). Collagen hydrolysates obtained at 90°C for 30 min indicated better gelatin properties (melting temperature, texture profile analysis and microstructure) when compared with that of hydrolysates obtained at 50 and 70°C. Therefore, heat treatment with a relatively higher temperature (90°C) and shorter time (30 min) is necessary to obtain hydrolyzed chicken bones collagen with good gelatin properties.

Hot-pressure extraction was utilized in this study to extract proteins from chicken bones at 130 °C. The obtained extracts were further used to prepare gelatin gels. Results demonstrated that the extraction time can significantly affect the composition of the chicken bone extracts (P 30 KDa was only visible in the extracts collected between 40 and 60 min. The highest contents of hydroxyproline, imino acids, and hydrophobic amino acids were all achieved in the chicken bone extracts after 120 min of extraction, being 3.9, 7.7, and 16.0 mg/g, respectively. The prepared gelatin properties were evaluated in terms of viscosity, storage and loss modulus, stability, gel strength, and their microstructures. Results indicated that gelatins made from chicken bone extracts of 20, 40, and 60 min extraction had better properties compared to that of 90 and 120 min. Significant correlations were identified between gelatin's composition and properties (P < 0.05). The abundance of proteins with MW of

BACKGROUND The cost of peptone is often a major contributor to costs in the fermentation industry. A novel method for preparation of peptone from chicken bone residue by using natural pancreas as catalyst was developed in this study, aiming to provide a way to convert waste into valuable peptone. RESULTS The molecular weight of chicken bone extract (CBE) hydrolyzed with pancreas or its combination with trypsin ranges between 100 and 1000 Da after 4 h of hydrolysis. CBE hydrolyzed with pancreas (5%, w/w) for 4 h shows higher degree of hydrolysis (DH) (23.60%) than that of 0.5% trypsin, and higher polypeptides and free amino acids content than that of 0.5% trypsin and 1% pancreas. Thus, it was selected for yeast, bacteria and fungi incubation, with commercial casein peptone as a control. Saccharomyces cerevisiae shows a similar growth curve in both media during 36 h incubation. Although Bacillus subtilis shows a longer lag phase (14 h) in chicken bone hydrolysate (CBH) than in the control (6 h), significantly higher OD600 in CBH was obtained after 24 h incubation (P

Hot-pressure extraction (HPE), which is regarded as a "green" technology, was applied to extract nutrients (protein, collagen, and minerals) from chicken bone residue (CBR). Amino acids (AA), color, and volatile flavor compounds of chicken bone extract (CBE) were also investigated. Results showed that contents of protein, total soluble solids, minerals, and collagen of CBE were positively correlated with extraction time and temperature. High ratios of protein (83.51%) and collagen (96.81%) were obtained with 135 °C and 120 min. Essential AA accounted for 31.03% to 47.73% of total AA in CBE. The percentage of bitter AA in TAA decreased from 28.94% to 25.02% at 0 min to 20.19% and 21.41% at 120 min, although fresh AA increased from 46.35% to 50.84% (0 min) to 53.14% (120 min) at 130 and 135 °C, respectively, indicating CBE was nutritionally beneficial with good flavor. Color and volatile flavor of CBE improved significantly after extraction, although calcium in CBE (4.2 to 4.8 mg/100 g) was relatively low compared with that of CBR (1078 mg/100 g). It can be concluded that HPE is a promising way to transform CBR into a nutritious flavorant substrate, but it is not an efficient way to extract calcium.

Shanxi Province is located in the east of China′s Loess Plateau.Traditional agriculture is restricted by the poor environmental conditions,water shortages and low soil fertility.The only way to develop agriculture is by adjusting the methods used to the local conditions and the development of animal husbandry.The shortage of browse and forage resources requires us to find appropriate grass species for the local conditions.Panicum virgatum L.and Galega orientalis Lam.cv.xinyin No.1 are two high yield and high quality grasses,so we introduced and cultivated them in the city of Taiyuan,Shanxi Province,China.By observing their phenophases,production,suitability,nutritional content,and so on,we found these two forage species can complete their reproductive cycle in the local climate and environmental conditions and they have many strong points such as better suitability,higher production and better quality than other species.We needed to do further study on them before introducing them as new species for Shanxi Province.We studied the photosynthetic characteristics of these two grasses in detail to determine if they could be introduced and cultivated in the Province.We analyzed the relationships between the diurnal changes of photosynthetic characteristics and environmental factors at different stages of growth.We also studied the characteristics of how leaf gas exchange indicators responded to changes in the natural environment,including especially light intensity.The findings confirm the adaptability of these two grasses and provide theoretical reference for their introduction and cultivation as well as a scientific basis for the establishment of sustainable grassland agriculture in this region. We selected different stages of growth in these two species to measure their photosynthetic and ecophysiological characteristics using a Portable LI-6400 Photosynthesis System(LI-COR,Inc.,Lincoln,NE,USA) on 25 May,6 July and 25 August 2010.The results show there were significant differences in the diurnal variations and light-response curves.(1) Xinyin No.1: The diurnal change of the net photosynthetic rate(Pn) had a bimodal pattern and had a clear midday depression.The daily averages of Pn,light use efficiency(LUE) and water use efficiency(WUE) during the branching stage were higher than in the podding stage.However,the daily averages of leaf temperature(Tl),transpiration rate(Tr),stomatal conductance(Gs) and intercellular CO2 concentration(Ci) in the podding stage were higher than in the branching stage.(2) Panicum virgatum: The diurnal change of Pn had a unimodal pattern.The daily averages of Pn and Tr in the jointing stage were higher than in the heading stage,and were also lowest during the flowering stage.The daily averages of WUE and Ci in the flowering stage were higher than in the jointing stage,which were the lowest during the heading stage.The daily averages of LUE and Tl in the heading stage were higher than in the jointing stage,and were the lowest during the flowering stage.(3) Pn was significantly positively correlated with Tr,Gs,stomatal limiting value(Ls),and photosynthetically active radiation(PAR),but significantly negatively correlated with Ci.Tr was significantly positively correlated with Gs,vapor pressure deficit(Vpdl),air temperature(Ta),Tl and PAR,but was also significantly negatively correlated with air CO2 concentration(Ca).Tl and Gswere significantly positively correlated with PAR.(4) By drawing the light response curves and by taking the relative physiological indexes into account,we could draw the conclusion P.virgatum is a heliophilic plant and Xinyin No.1 is a shade tolerant plant based on relevant evaluation criteria.Also,P.virgatum has greater adaptability to diverse environments than Xinyin No.1.