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doi: 10.17113/ftb.54.04.16.4553

A Systematic Approach to the Comparison of Cost Efficiency of Endopeptidases for the Hydrolysis of Atlantic Salmon (Salmo salar) By-Products

 

Tone Aspevik*, Henning Egede-Nissen and Åge Oterhals
 

Nofima, Kjerreidviken 16, N-5141 Fyllingsdalen, Norway





Article history:
Received    December 4, 2015
Accepted   June 1, 2016
cc


Key words:
endopeptidase, fish protein hydrolysate, degree of hydrolysis, pH-STAT, protein recovery, cost efficiency


Summary:
The hydrolytic and cost efficiencies of five endopeptidases (Alcalase 2.4L, Corolase 7089, Neutrase 0.8L, Promod 671L and Protex 7L) to hydrolyze Atlantic salmon by-products were compared at standardized activity levels based on a casein assay. The substrate was characterized prior to the hydrolytic experiments (pH=6.5, t=50 °C) to obtain substrate-specific constants for nitrogen to protein mass (in g) ratio, i.e. conversion factor fN=5.23 and total amount of peptide bonds (htot)=9.3 mmol per g of protein. At low enzyme activity to substrate ratio, all enzymes were equally efficient in hydrolyzing the substrate. At highest enzyme activity to substrate ratio, Protex 7L, Alcalase 2.4L and Promod 671L gave higher degree of hydrolysis (DH=14.2–14.6 %) than Corolase 7089 (13.2 %) and Neutrase 0.8L (11.6 %) after 120 min of hydrolysis. No differences were observed in protein recovery (yield of solubilized protein) relative to DH. Determination of DH was followed by the pH-STAT and o-phthaldialdehyde methods. Based on pH-STAT data, response surface regression models were established based on the combined effects of hydrolysis time and enzyme activity to substrate ratio on DH and protein recovery. The modelling approach was combined with enzyme cost to identify the most cost-efficient enzyme (Protex 7L).



 


*Corresponding author:  email3   tone.aspevik@nofima.no
                                      tel3  +47 55 501 244

                                      fax2  +47 55 501 299


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doi: 10.17113/ftb.54.04.16.4623 

Optimization of Pumpkin Oil Recovery by Using Aqueous Enzymatic Extraction and Comparison of the Quality of the Obtained Oil with the Quality of Cold-Pressed Oil

 

Iwona Konopka*, Beata Roszkowska, Sylwester Czaplicki and Małgorzata Tańska
 

Chair of Food Plant Chemistry and Processing, Faculty of Food Sciences, University of Warmia and Mazury in Olsztyn, Pl. Cieszyński 1, PL-10-726 Olsztyn, Poland





Article history:
Received    January 27, 2016
Accepted   July 29, 2016
cc


Key words:
enzymatic maceration, pumpkin oil, recovery optimization, induction period, phytochemicals


Summary:
The study was carried out to optimize pumpkin oil recovery in the process of aqueous extraction preceded by enzymatic maceration of seeds, as well as to compare the quality of the obtained oil to the quality of cold-pressed pumpkin seed oil. Hydrated pulp of hulless pumpkin seeds was macerated using a 2 % (by mass) cocktail of commercial pectinolytic, cellulolytic and proteolytic preparations (Rohapect® UF, Rohament® CL and Colorase®
7089). The optimization procedure utilized response surface methodology based on Box-Behnken plan of experiment. The optimized variables of enzymatic pretreatment were pH, temperature and maceration time. The results showed that the pH value, temperature and maceration time of 4.7, 54 °C and 15.4 h, respectively, were conducive to maximize the oil yield up to 72.64 %. Among these variables, the impact of pH was crucial (above 73 % of determined variation) for oil recovery results. The oil obtained by aqueous enzymatic extraction was richer in sterols, squalene and tocopherols, and only slightly less abundant in carotenoids than the cold-pressed one. However, it had a lower oxidative stability, with induction period shortened by approx. 30 % in relation to the cold-pressed oil.


 


*Corresponding author:  email3  iwona.konopka@uwm.edu.pl
                                      tel3  +48 89 523 3625
                                      fax2  +48 89 523 3466


getpdf  NLM-PubMed-Logo  doi: 10.17113/ftb.54.04.16.4651  

Oxygen Consumption by Postfermentation Wine Yeast Lees: Factors Affecting Its Rate and Extent under Oenological Conditions

 

Volker Schneider1*, Jonas Müller2 and Dominik Schmidt3
 

1Schneider-Oenologie, Rupertusweg 16, DE-55413 Weiler bei Bingen, Germany
2Project Group for System Analysis and Modeling, Hochschule Geisenheim University, von-Lade-Str. 1, DE-65366 Geisenheim, Germany
3Modeling and Simulation Group, Hochschule Geisenheim University, von-Lade-Str. 1, DE-65366 Geisenheim, Germany



Article history:
Received   February 14, 2016
Accepted  June 30, 2016
cc


Key words:
wine, yeast lees, dissolved oxygen, oxidation, sulfur dioxide, oxygen consumption


Summary:
Postfermentation wine yeast lees show antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white and red wines using fluorescence-based oxygen sensors operating in a nondestructive way. In model solution, the oxygen consumption rate of yeast lees was shown to depend on their amount, yeast strain, sulfur dioxide and temperature. It is slightly lower in red than in white wines. It is strongly decreased by current levels of free sulfur dioxide, thus excluding the complementary use of both as antioxidants in wine. However, in 25 randomly sampled white wines produced under commercial conditions, the rate and extent of oxygen consumption during the first six months of postfermentation had no significant correlation with any of these interacting factors, making it diffi cult to predict the actual antioxidant effect of yeast lees. In these wines, yeast lees consumed 0 to 47 % of the dissolved oxygen. Although total oxygen consumption capacity of yeast lees is not a limiting factor under commercial winemaking conditions, their oxygen consumption proceeds at a limited rate that reduces but cannot totally prevent concomitant chemical oxidation of
the wine.


 


*Corresponding author:  email3  Schneider.Oenologie@gmail.com
                                      tel3  +49 6721 34744
                                


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doi: 10.17113/ftb.54.04.16.4440 

Evaluation of Beer Fermentation with a Novel Yeast Williopsis saturnus

 

Shao-Quan Liu1,2* and Althea Ying Hui Quek1
 

1Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 3, 117543 Singapore, Singapore
2National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, 215123 Suzhou, PR China





Article history:
Received    September 22, 2015
Accepted   May 20, 2016
cc

Key words:
fermentation, beer, volatiles, esters, Williopsis sp., yeasts


Summary:
The aim of this study is to evaluate the potential of a novel yeast Williopsis saturnus var. mrakii NCYC 500 to produce fruity beer. Fermentation performance of W. mrakii and beer volatile composition were compared against that fermented with Saccharomyces cerevisiae Safale US-05. oBrix, sugar and pH differed significantly between the two types of beer. A total of 8 alcohols, 11 acids, 41 esters, 9 aldehydes, 8 ketones, 21 terpenes and terpenoids, 5 Maillard reaction products and 2 volatile phenolic compounds were detected. Yeast strain Safale US-05 was more capable of producing a wider range of ethyl and other esters, while yeast strain NCYC 500 produced significantly higher amounts of acetate esters. Strain NCYC 500 retained more terpenes and terpenoids, suggesting that the resultant beer could possess more of the aromatic hint of hops. This study showed that W. saturnus var. mrakii NCYC 500 could ferment wort to produce low-alcohol beer with higher levels of acetate esters, terpenes and terpenoids than yeast S. cerevisiae Safale US-05.


 



*Corresponding author:  email3   chmLsq@nus.edu.sg
                                      tel3  +65 6516 2687
                                      fax2  +65 6775 7895


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doi: 10.17113/ftb.54.04.16.4248 

Biochemistry of Apple Aroma: A Review



Miguel Espino-Díaz1, David Roberto Sepúlveda1, Gustavo González-Aguilar2 and Guadalupe I. Olivas1


1Research Center for Food and Development (CIAD), Rio Conchos S/N, MX-31570 Cuauhtémoc, Mexico
2Research Center for Food and Development (CIAD), Carretera a la Victoria km. 0.6, MX-83000 Hermosillo, Mexico



Article history:
Received    May 7, 2015
Accepted   May 16, 2016
cc


Key words:
apple aroma, volatile compounds, precursor, lipoxygenase (LOX), alcohol dehydrogenase (ADH), alcohol acyltransferase (AAT), pathway


Summary:
Flavour is a key quality attribute of apples defined by volatile aroma compounds. Biosynthesis of aroma compounds involves metabolic pathways in which the main precursors are fatty and amino acids, and the main products are aldehydes, alcohols and esters. Some enzymes are crucial in the production of volatile compounds, such as lipoxygenase, alcohol dehydrogenase, and alcohol acyltransferase. Composition and concentration of volatiles in apples may be altered by pre- and postharvest factors that cause a decline in apple flavour. Addition of biosynthetic precursors of volatile compounds may be a strategy to promote aroma production in apples. The present manuscript compiles information regardingm the biosynthesis of volatile aroma compounds, including metabolic pathways, enzymes and substrates involved, factors that may affect their production and also includes a wide number of studies focused on the addition of biosynthetic precursors in their production.




 


*Corresponding author:  email3  golivas@ciad.mx
                                      tel3  +52 625 581 2920
                                      fax2  +52 625 581 2921

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