枸杞果酒发酵工艺优化及营养功能成分分析

该研究以新鲜枸杞为原料制备果酒,并对枸杞果酒营养功能成分进行分析。以初始糖度、酵母接种量、发酵温度和初始pH值为自变量,以感官评分为响应值,通过单因素和响应面试验优化枸杞果酒发酵工艺条件。结果表明,枸杞果酒的最佳发酵工艺条件为初始糖度27 °Bx,酵母接种量0.20%,发酵温度22 ℃,初始pH值5.0。在此优化条件下,枸杞果酒酒精度为12.24%vol,感官评分为91.80分。枸杞果酒中的营养成分总糖、蛋白质、氨基酸的含量分别为（2.27±0.16） g/100 mL、（0.62±0.04） g/100 mL、（588.12±10.23） mg/100 mL;功能成分总多酚、总黄酮、多糖和甜菜碱的含量分别为（1.88±0.06） mg没食子酸当量（GAE）/mL、（1.63±0.03） mg 芦丁当量（RE）/mL、（7.17±0.01） mg/mL和（2.55±0.04） mg/mL。     

Monitoring of firmness evolution of peaches during storage by combining acoustic and impact methods

Firmness is a very important quality property in peach. The storage of peach affects its subsequent softening process and shelf life. The temperature and duration of storage mainly influence the firmness of stored fruit, and monitoring the evolution of fruits enables producers to manage its commercial life. The objective of the present study was to use non-destructive acoustic and impact tests to estimate firmness of peaches and to elucidate the influence of storage temperature and of time on the softening process of peach. Continuous and classification models based on variables obtained from non-destructive methods were developed. Parameters obtained from non-destructive methods were compared to destructive reference tests. The maximum force in ball compression correlated well with the maximum acceleration from impact test (r² = 0.75), and with a band magnitude parameter from acoustic test (r² = −0.71). Combining impact and acoustic parameters, the multiple correlation coefficient increases up to 0.91 (adjusted R² = 0.82) in the prediction of the maximum force in ball compression. Classification models based on both non-destructive parameters and sorting peaches into two classes of firmness, showed scores of well classified higher than 90%.     

Buckling behaviour of imperfect ring-stiffened cone–cylinder intersections under internal pressure

Cone–cylinder intersections are used commonly in pressure vessels and piping. In the case of a cone large end-to-cylinder intersection under internal pressure, the intersection is subject to a large circumferential compressive force. While both the cone and the cylinder may be locally thickened to strengthen the intersection, it is often desirable and convenient to provide an annular plate ring at the cone-to-cylinder joint to supplement local thickening or as an alternative strengthening measure, leading to a ring-stiffened cone–cylinder intersection. Only limited work has been carried out specifically on ring-stiffened cone–cylinder intersections under internal pressure. This paper presents the first experimental study on such intersections. In addition to the presentation of test results including geometric imperfections, failure behaviour and the determination of buckling mode and load based on displacement measurements, results from nonlinear bifurcation analysis using the perfect shape and nonlinear analysis using the measured imperfect shape are presented and compared with the experimental results.     

Amination of ethanolamine over cobalt modified H-ZSM-5 catalysts

The amination of ethanolamine (EA) with ammonia proceeded over a cobalt modified H-ZSM-5 under rather moderate conditions in a fixed-bed reactor. These catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, temperature-programmed reduction, and infra-red spectroscopy. The reaction mechanism was also discussed, and Co⁰ is believed to be the active site of the hydrogenation/dehydrogenation process and the acid sites of H-ZSM-5 is thought to be the active site of the amination process. Thus, the synergetic effect of the cobalt and the acidic sites of H-ZSM-5 is necessary for the amination of ethanolamine.     

Working fluids comparison and thermodynamic analysis of a transcritical power and ejector refrigeration cycle (TPERC)

The combined power and cooling cycles driven by waste heat and renewable energy can provide different kinds of energy forms and achieve a higher thermodynamic efficiency. However, only a few researchers have focused on the improvement of temperature matching between the heat source and working fluid. This paper proposes a transcritical power and ejector refrigeration cycle (TPERC) to improve temperature matching between the heat source and working fluid. Based on the modelling of the TPERC system, a comparison of working fluids and the effects of system parameters on the cooling capacity, work output, thermal efficiency and exergy efficiency are discussed. The results show that of the seven working fluids selected, R1234ze has the largest thermal efficiency and exergy efficiency, principally due to having the highest critical temperature. At the identical turbine back pressure, condensing temperature and evaporation temperature, the turbine inlet temperature and its corresponding generation pressure have little impact on thermal efficiency.     

Disruption and sedimentation of casein micelles and casein micelle isolates under high-pressure homogenization

Native casein micelles were isolated from raw skim milk by ultrafiltration (< 30 kDa) or microfiltration (< 0.2 μm) and subjected to high-pressure homogenization (HPH) at 100, 200, 250, 300, and 350 MPa. Of particular interest was the effect of HPH on casein micelle size in solutions varying in ionic strength (0, 5, 10, and 15 mM CaCl₂) and micelle size populations. Particle size distribution reflected an initial decrease in micelle diameter in all samples at 100 MPa. In samples containing 10 and 15 mM CaCl₂, there was an abrupt increase in particle size and subsequent casein precipitation followed by sedimentation upon centrifugation at elevated pressures (300 and 350 MPa). The amount of sedimentable casein protein increased as CaCl₂ concentration (10 and 15 mM) and pressure (300 and 350 MPa) increased as determined by UV absorbance of sample supernatant. SDS-PAGE indicated extensive micellar disruption at elevated pressures (300 and 350 MPa) and confirmed that the sedimented portion of the samples contained casein proteins and minimal amounts of whey proteins. Results indicated that through HPH treatment casein micelle size can be modified based on CaCl₂ concentration and pressure applied. Based on these findings, HPH in combination with an appropriate suspending medium has the ability to modify micelles to a desired size for a number of potential applications.Industrial relevanceThe modification of structure-function properties of the casein micelle from bovine milk by using high-pressure homogenization is relevant in (1) the development of new ingredients to change rheological/textural properties of dairy based foods, and (2) the discovery of new and/or improved functionalities for protein quaternary structures.     

配粉工艺的常见问题及解决方法

介绍了配粉的功能与工艺,并阐述了配粉工艺中容易发生的一些问题及解决方法。