Orange processing waste valorisation for the production of bio-based pigments using the fungal strains Monascus purpureus and Penicillium purpurogenum

Orange processing wastes have been evaluated for the production of pigments by the fungal strains Monascus purpureus ATCC 16365 and Penicillium purpurogenum CBS 113139. Solid state fermentations were initially conducted on waste orange peels with the fungal strain M. purpureus aiming to assess various pigment extraction methods, the effect of particle size as well as the effect of nitrogen addition and incubation time. Under the optimum conditions, solid state fermentations were also performed with the strain P. purpuronegum to evaluate pigment production on waste orange peels. M. purpureus was more efficient than P. purpurogenum for the production of pigments during solid state fermentation, yielding 9 absorbance units (AU) per g of dry fermented substrate. Semi-solid state fermentations were subsequently conducted by suspending waste orange peels in liquid media leading to pigment production of up to 0.95 AU mL−1. Submerged fermentations were carried out with both fungal strains using aqueous extracts from either boiled or hydrodistilled orange peel residues as the sole fermentation medium showing that up to 0.58 AU mL−1 of pigment production could be achieved. Each fermentation feedstock and fermentation mode influenced significantly the production of pigments by each fungal strain used

Production of white wine by Saccharomyces cerevisiae immobilized on grape pomace

White wine was produced with Saccharomyces cerevisiae cells immobilized on grape pomace, by natural adsorption. The support, the main solid waste from the wine industry, consisted of the skins, seeds and stems. Immobilization was tested using different media, namely complex culture medium, raw grape must and diluted grape must. Grape pomace was revealed to be an appropriate support for yeast cell immobilization. Moreover, grape must was shown to be the most suitable medium as immobilized cells became adapted to the conditions in the subsequent alcoholic fermentation in the wine-making process. The wines produced, either with immobilized cells or with free cells, were subjected to chemical analysis by HPLC (ethanol,glycerol, sugars and organic acids) and by gas chromatography (major and minor volatile compounds); additionally, colour (CIELab) and sensory analysis were performed. The use of immobilized systems to conduct alcoholic fermentation in white wine production proved to be a more rapid and a more efficient process, especially when large amounts of SO2 were present in the must. Furthermore, the final wines obtained with immobilized cells demonstrated improved sensory properties related to the larger amounts of ethanol and volatile compounds produced. The more intense colour of these wines could be a drawback, which could be hindered by the reutilization of the biocatalyst in successive fermentations.Zlatina Genisheva gratefully acknowledges FCT (contract/grant number: SFRH/BD/48186/2009) for financial support of this work. The authors would like to thank Divisao de Vitivinicultura Direccao Regional de Agricultura e Pescas do Norte for providing the grape pomace for yeast immobilization and the must to conduct alcoholic fermentations. The authors thank also Professor Joao Linhares for help in computing the CIELab coordinates

Extraction of Phenolic Compounds from Palm Oil Processing Residues and Their Application as Antioxidants

Nusproizvodi proizvodnje palminog ulja, i to pogača od palminih sjemenki, palmina vlakna, ljuske palminih sjemenki i prazni grozdovi palminog ploda, upotrijebljeni su za ekstrakciju polifenolnih spojeva. Među tim nusproizvodima je pogača od palminih sjemenki sadržavala najviše ukupnih fenolnih spojeva, i to 5,19 mg u g suhe tvari, izraženih kao ekvivalent galne kiseline, dok je najmanje imao prazni grozd palminog ploda, i to 1,79 mg/g. Radi optimiranja ekstrakcije fenola ispitani su sljedeći parametri: vrijeme ekstrakcije i omjer tekuće i krute tvari. Najveći ukupni udjel fenola od 5,35 mg/g pri omjeru tekuće i krute tvari od 40:1 tijekom ekstrakcije od 20 min imala je pogača od palminih sjemenki. Pomoću HPLC-DAD metode određeni su glavni fenolni spojevi iz nusprodukata proizvodnje palminog ulja. Pogača od palminih sjemenki sadržavala je najviše pirogalola, te 4-hidroksibenzojeve, galne i ferulinske kiseline. Prazni grozdovi palminog ploda i palmina vlakna bili su bogati hidroksibenzojevom kiselinom, dok je pirogalol bio dominantan sastojak ekstrakta ljuski palminih sjemenki. Svi su ekstrakti imali oksidacijsku aktivnost, koja je potvrđena DPPH analizom, te ispitana dodatkom ekstrakta suncokretovom ulju radi produljenja roka trajanja. Dodatkom 0,8 % ekstrakta pogače od palminih sjemenki povećalo se indukcijsko vrijeme suncokretovog ulja za više od 50 %. Rezultati istraživanja potvrđuju da je pogača od palminih sjemenki nusproizvod s dodanom vrijednošću koji se može upotrijebiti kao antioksidans u prehrambenoj industriji.The side streams derived from the palm oil production process, namely palm kernel cake, palm pressed fibre, palm kernel shells and empty fruit bunches, were evaluated as sources of phenolic compounds. Among these streams, kernel cake had the highest total phenolic content (in mg of gallic acid equivalents (GAE) per g of dry sample) with a value of 5.19, whereas the empty fruit bunches had the lowest value (1.79). The extraction time and liquid-to-solid ratio were investigated to optimize the phenolic extraction. Kernel cake exhibited the highest total phenolic content (5.35 mg/g) with a liquid-to-solid ratio of 40:1 during 20 min of extraction. The main phenolic compounds of the extracts deriving from all byproduct streams were also identified and quantified with HPLC-DAD. Pyrogallol, 4-hydroxybenzoic acid, gallic acid and ferulic acid were the main compounds found in kernel cake extracts. Empty fruit bunch and pressed fibre extracts were also rich in 4-hydroxybenzoic acid, while pyrogallol was the predominant compound in kernel shell extracts. All extracts showed antioxidant activity as it was indicated from the results of DPPH analysis and subsequently tested in sunflower oil aiming to prolong its shelf life. The addition of 0.8 % kernel cake extract increased the induction time of sunflower oil more than 50 %. According to the results obtained in this study, kernel cake extracts could be considered as a value-added co-product with a potential application as antioxidants in the food industry

Volatilome of chill-stored European Seabass (Dicentrarchus labrax) fillets and Atlantic Salmon (Salmo salar) slices under modified atmosphere packaging

Fish spoilage occurs due to production of metabolites during storage, from bacterial action and chemical reactions, which leads to sensory rejection. Investigating the volatilome profile can reveal the potential spoilage markers. The evolution of volatile organic molecules during storage of European seabass (Dicentrarchus labrax) fillets and Atlantic salmon (Salmo salar) slices under modified atmosphere packaging at 2 °C was recorded by solid-phase microextraction combined with gas chromatography-mass spectrometry. Total volatile basic nitrogen (TVB-N), microbiological, and sensory changes were also monitored. The shelf life of seabass fillets and salmon slices was 10.5 days. Pseudomonas and H2S-producing bacteria were the dominant microorganisms in both fish. TVB-N increased from the middle of storage, but never reached concentrations higher than the regulatory limit of 30–35 mg N/100 g. The volatilome consisted of a number of aldehydes, ketones, alcohols and esters, common to both fish species. However, different evolution patterns were observed, indicating the effect of fish substrate on microbial growth and eventually the generation of volatiles. The compounds 3-hydroxy-2-butanone, 2,3-butanediol, 2,3-butanedione and acetic acid could be proposed as potential spoilage markers. The identification and quantification of the volatilities of specific fish species via the development of a database with the fingerprint of fish species stored under certain storage conditions can help towards rapid spoilage assessment

Consecutive alcoholic fermentations of white grape musts with yeasts immobilized on grape skins : effect of biocatalyst storage and SO2 concentration on wine characteristics

Abstract Saccharomyces cerevisiae yeasts, immobilized by natural adsorption on grape skins, were used to carry out the alcoholic fermentation step of a winemaking process. The viability of the immobilized cells was evaluated by the implementation of 7 successive fermentations of a white grape must containing 30 mg/L of SO2. The time to complete alcoholic fermentation, the physicochemical characteristics of the produced wines (ethanol, glycerol, organic acids, volatile compounds, color) and sensory properties were evaluated. A traditional fermentation with free cells was used as control. Three other fermentations were conducted after storage of the immobilized biocatalyst (30 d, 4 oC), the first one in the same conditions of the earlier assays, and the other two with higher amounts of SO2 (60 mg/L, 90 mg/L). Wines produced with immobilized cells presented physicochemical and sensory characteristics similar to those traditionally produced with free cells. After three consecutive fermentations, chromatic characteristics became similar to those of traditional wines, but the fermentation time had been reduced from 7 d to 4 d. The fermentative process and the characteristics of the produced wines were not significantly affected by the use of higher amounts of SO2. Immobilized biocatalysts could be stored at least one month without losing its activity.Zlatina Genisheva gratefully acknowledges FCT (Contract/grant number: SFRH/BD/48186/2009) and the Project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF. NORTE-07-0124-FEDER-000028 Co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER, for the financial support of this work

Study of secondary aroma by GS/MS of wines produced by immobilized cells

Repeated batch fermentations of grape must at different temperatures were performed using immobilized cells of Saccharomyces cerevisiae strain AXAZ-1 on delignified cellulosic material (DCM), gluten pellets (GP) and grape skins. The aim of this study was the investigation of the volatile components of the final product (qualitatively and quantitatively) as well as the monitoring of the evolution of some volatiles during the alcoholic fermentation. For comparison reasons, fermentations using free cells were performed under the same conditions. The immobilized biocatalyst on DCM and GP resulted in significant increase of the fermentation rate in comparison with free cells. The produced wines had similar physicochemical characteristics, e.g. alcoholic strength, total and volatile acidity, residual sugar and pH. The GC/MS analysis proved that the cell immobilization and the fermentation temperature did not cause serious changes in the qualitative composition of the wine aroma. Esters, higher alcohols and volatile fatty acids were the major compounds identified in all wines. However, the effect of immobilization and temperature caused signigicant changes on the quantitative profile of the wine aroma. Wines produced by DCM contained higher amounts of esters, at every temperature. The relative percentage of esters on total volatiles remained practically constant with temperature decrease, in the case of immobilized cells, whereas it decreased in the case of free cells. Wines produced by GP-supported biocatalyst contained higher amounts of alcohols. DCM-supported biocatalyst and free cells produced wines with similar contents of alcohols. The decrease of temperature resulted in the decrease of their amount. The same was observed for the concentration of volatile fatty acids. GPsupported biocatalyst produced wines with smaller amounts of acids. Free and immobilized cells on DCM produced wines with similar contents of volatile acids. The kinetics of volatiles’ production were similar for free and immobilized cells on DCM. In all cases, immobilized cells showed a higher rate of volatile production. This was directly connected to sugar consumption. The evolution patterns of acetate esters were different from those of ethyl esters. Generally, ethyl esters reached a maximum earlier than acetates. In most cases, a two-peak profile was observed for ethyl esters. For the first time, grape skins were used as a natural support for S. cerevisiae immobilization. Cell immobilization was confirmed by electron microscopy. In repeated batch fermentations of grape must, the immobilized biocatalyst caused an significant increase in the fermentation rate in comparison with free cells, without any loss of the activity, even at very low temperatures (5oC). The alcohol production and the maximum specific rates on glucose and fructose substrate were much better for cells immobilized on grape skins. They increased exponentially with temperature increase. Qualitative characteristics, such as total acidity, volatile acidity and residual sugars were similar with those of commercial dry wines. Wines produced by immobilized cells had lower volatile acidity than those produced by free cells. They were very clear, especially at low fermentation temperatures. GC/MS analysis showed that the qualitative profile of the produced wines was similar in all cases. The majority of the identified volatile compounds was formed during the alcoholic fermentation and consisted of esters, alcohols and acids. Immobilized cells gave wines with a higher content of esters. The amount of ethyl esters decreased with temperature decrease, whereas the amount of acetate esters increased with temperature decrease (25-15oC), reaching a maximum. The content of volatile alcohols was more pronounced in wines produced by free cells. It decreased dramatically at low fermentation temperatures (10oC). Volatile fatty acids were produced in greater quantities by free cells at higher temperatures (25-20oC). The opposite was observed at low fermentation temperatures (15-10oC). Investigation of the volatiles’ evolution during fermentation, showed that esters were produced shortly after the midpoint of fermentation. For immobilized cells, the formation of esters was continued until the end of the process. Similar kinetics were observed for amyl alcohols and 2-phenylethanol, whereas propanol and isobutanol were formed during the whole alcoholic fermentation period with a constant rate. Acetaldehyde and acetoin were synthesized in the early stages. Afterwards, their amount decreased. Acetic acid was formed throughout alcoholic fermentation with a costant rate, which was greater in the case of free cells at every temperature studied

Gas Chromatography–Mass Spectrometry-Based Metabolite Profiling for the Assessment of Freshness in Gilthead Sea Bream (Sparus aurata)

Gilthead sea bream (Sparus aurata) is one of the most important farmed Mediterranean fish species, and there is considerable interest for the development of suitable methods to assess its freshness. In the present work, gas chromatography–mass spectrometry-based metabolomics was employed to monitor the hydrophilic metabolites of sea bream during storage on ice for 19 days. Additionally, the quality changes were evaluated using two conventional methods: sensory evaluation according to European Union’s grading scheme and K-value, the most widely used chemical index of fish spoilage. With the application of chemometrics, the fish samples were successfully classified in the freshness categories, and a partial least squares regression model was built to predict K-value. A list of differential metabolites were found, which were distinguished according to their evolution profile as potential biomarkers of freshness and spoilage. Therefore, the results support the suitability of the proposed methodology to gain information on seafood quality

Volatile organic compounds of microbial and non-microbial origin produced on model fish substrate un-inoculated and inoculated with gilt-head sea bream spoilage bacteria

Volatile organic compounds (VOCs) origination during fish spoilage is attributed to either decomposition of fish constituents or metabolic activity of spoilage bacteria. To identify microbiological spoilage markers it is essential to know which VOCs are microbial metabolites. VOCs produced in sterile fish juice agar (FJA) model substrate made from gilt-head sea bream (Sparus aurata) flesh juice, inoculated or not with spoilage bacteria isolated from sea bream fillets were detected using SPME/GC-MS technique. Three groups of spoilage bacteria (Pseudomonas, Shewanella and Carnobacterium/Lactobacillus strains) were used to inoculate Petridishes with FJA and stored at 0 and 15 °C under air and commercial Modified Atmosphere Package (MAP CO2: 60%, O2: 10%, N2: 30%). Bacterial growth was also monitored. VOCs that were detected in sterile substrate and their amounts were not higher in inoculated FJA were presumably of non-microbial origin. VOCs that were detected only in inoculated FJA were metabolic products of spoilage bacteria. Some of VOCs were associated with metabolic activity of a particular microbial group, e.g. ethyl esters were associated with Pseudomonas, while 2-, 3-methylbutanal and 3-hydroxy-2-butanone with LAB. Few microbial metabolites increased during storage showing their potential as spoilage markers of gilt-head sea bream and the possible use for rapid freshness assessment. © 2016 Elsevier Lt