Membrane processing of grape must for control of the alcohol content in fermented beverages

The great demand of beverages, both alcohol-free and with low alcohol content, is a great challenge for the production of beverages with controlled alcohol content through the use of sustainable enological practices. The present work addresses this challenge with the processing of grape must by reverse osmosis (RO) for must reconstitution with different sugar contents prior to the alcoholic fermentation. The original must came from grapes grown in Quinta do Quinto, in Santarém, collected after destemming and mechanic crushing, and preserved in a refrigerated chamber at -1.6 °C until processing by RO. The RO processing was carried out in Escola Superior Agrária de Santarém, with a pilot plant equipped with RO spiral wound modules, M38RO, from Alfa Laval, Denmark. The total membrane permeation area is 15 m2. The work pressure was 55 bar. The original must had 23.7 oBrix, a density of 1108 g.L-1, 15.2% (v/v) of probable alcohol, and a conductivity of 2.01 mS.cm-1. The must reconstitution was carried out, by mixing the concentrated grape must with the vegetal water produced by RO (permeate) to obtain beverages with a nominal alcohol content of 5%, 7%, 10% and 13% (v/v). The fermentation average temperature was between 18.2 and 19.7 °C, and the final density rounded about 993 g.cm-3. The beverages were analysed by different parameters, including total polyphenols, total anthocyanins, colour intensity and hue, the coordinates CIELab, alcohol content, total acidity, volatile acidity, pH, free SO2 and total SO2. The attributes of the beverage, corresponding to the visual appearance, aroma and taste senses, as well as the overall judgment were evaluated by the tasters. The proposed method can produce beverages with controlled low alcohol content. The decrease of the alcohol content led to lower content of polyphenols compounds which influenced the sensory evaluation.info:eu-repo/semantics/publishedVersio

Exploiting multi-core architectures for reduced-variance estimation with intractable likelihoods

© 2016 International Society for Bayesian Analysis. Many popular statistical models for complex phenomena are intractable, in the sense that the likelihood function cannot easily be evaluated. Bayesian estimation in this setting remains challenging, with a lack of computational methodology to fully exploit modern processing capabilities. In this paper we introduce novel control variates for intractable likelihoods that can dramatically reduce the Monte Carlo variance of Bayesian estimators. We prove that our control variates are well-defined and provide a positive variance reduction. Furthermore, we show how to optimise these control variates for variance reduction. The methodology is highly parallel and offers a route to exploit multi-core processing architectures that complements recent research in this direction. Indeed, our work shows that it may not be necessary to parallelise the sampling process itself in order to harness the potential of massively multi-core architectures. Simulation results presented on the Ising model, exponential random graph models and non-linear stochastic differential equation models support our theoretical findings

Kolonisasi Nyamuk Aedes Aegypti Menggunakan Tehnik Membran Artifisial Di Laboratorium

Latar belakang Kolonisasi nyamuk Aedes aegypti di laboratorium dapat menggunakan AMF (Artificial Membrane Feeding). Membran artifisial yang sering digunakan seperti parafilm M, latek kondom, dan kulit mencit. Penggunaan membran artifisial mempengaruhi kemampuan reproduksi nyamuk Ae. aegypti. Tujuan Mengetahui pengaruh penggunaan membran artifisial parafilm M, latek kondom, dan kulit mencit terhadap persentase nyamuk dewasa yang mampu menghisap darah, rerata jumlah telur dan persentase daya tetas telur nyamuk Ae. aegypti di laboratorium. Metode Penelitian ini merupakan penelitian eksperimental murni. Nyamuk Ae. aegypti sebanyak 30 ekor (8 replikasi) dimasukkan ke dalam gelas rearing yang telah diberi AMF berisi darah dengan membran yang berbeda jenisnya yaitu, parafilm M, latek kondom dan kulit mencit. Blood feeding dilaksanakan selama 60 menit, setelah 60 menit kemudian dihitung jumlah nyamuk yang mampu menghisap darah. Nyamuk yang telah menghisap darah kemudian dimasukkan ke dalam gelas rearing secara individu untuk bertelur. Jumlah telur yang diproduksi dihitung setelah 7 hari paska pemberian umpan darah. Telur kemudian direndam dengan air selama 7 hari untuk pengamatan daya tetas. Hasil dianalisis dengan Uji One way ANNOVA. Hasil Persentase nyamuk Ae. aegypti yang mampu menghisap darah menunjukkan perbedaan signifikan (p=0,000) antara membran parafilm M (88,33%), latek kondom (45,42%), dan kulit mencit (86,66%). Jumlah telur per ekor nyamuk betina juga menunjukkan beda signifikan (p=0,002) antara membran parafilm M (51,63), latek kondom (50,53), dan kulit mencit (53,65), sedangkan persentase daya tetas telur juga menunjukkan perbedaan signifikan (p=0,02) antara membran parafilm M (99,94%), latek kondom (99,91%), dan kulit mencit (99,96%). Kesimpulan Membran artifisial kulit mencit menunjukkan hasil yang lebih baik sehingga lebih direkomendasikan sebagai metode rearing nyamuk Ae. aegypti di laboratorium