Papers by Manuel Malfeito Ferreira
Beverages
Sulfite is a common preservative in wine, but the spoilage yeast Brettanomyces bruxellensis can p... more Sulfite is a common preservative in wine, but the spoilage yeast Brettanomyces bruxellensis can produce volatile phenols even with the recommended sulfite dose. The purpose of this study was to examine how wine components, p-coumaric acid (a precursor of volatile phenols), and micronutrients influence culturability, viability, and volatile phenols production by B. bruxellensis under sulfite stress. In red wine, a high sulfite dose (potassium metabisulfite, 100 mg L−1) led to an immediate death phase followed by growth recovery after two weeks. However, 4-ethylphenol (4-EP) was continuously produced by dead or nonculturable cells. Nonetheless, an event of growth recovery could not be observed in the case of the model wine. However, when the model wine was supplemented with minerals and vitamins, both growth recovery and 4-EP production were noticed, suggesting that the minerals and vitamins played an important role in maintaining the viability of cells under the sulfite stress. The y...
American Journal of Enology and Viticulture
Applied Microbiology
Food poisoning by staphylococcal enterotoxins (SE) is a major cause of foodborne illness, often a... more Food poisoning by staphylococcal enterotoxins (SE) is a major cause of foodborne illness, often associated with coagulase-positive staphylococci (CPS). The increase in the number of methicillin-resistant Staphylococcus aureus (MRSA) strains is another major problem associated with CPS. However, reports of the association of SE and methicillin-resistant Staphylococcus with coagulase-negative staphylococci (CNS) are beginning to re-emerge. In this context, the aim of this study is to investigate the presence of staphylococcal enterotoxin genes and to characterize the phenotypic and genotypic antimicrobial resistance in 66 isolates of Staphylococcus spp. (47 CNS and 19 CPS) recovered from ready-to-eat (RTE) street food sold in Maputo, Mozambique. Seven virulence genes encoding SE (sea, seb, sec, sed and see) and two toxins (hlb and sak) were screened by multiplex PCR (MPCR). Antimicrobial resistance against 12 antibiotics was evaluated by the disk diffusion method. The presence of gene...
Microorganisms
The yeast Brettanomyces bruxellensis is one of the most dangerous wine contaminants due to the pr... more The yeast Brettanomyces bruxellensis is one of the most dangerous wine contaminants due to the production of phenolic off-flavors such as 4-ethylphenol. This microbial hazard is regularly tackled by addition of sulfur dioxide (SO2). Nevertheless, B. bruxellensis is frequently found at low levels (ca 103 cells/mL) in finished wines. Besides, consumers health concerns regarding the use of sulfur dioxide encouraged the search for alternative biocontrol measures. Recently, we found that Saccharomyces cerevisiae secretes a natural biocide (saccharomycin) that inhibits the growth of different B. bruxellensis strains during alcoholic fermentation. Here we investigated the ability of S. cerevisiae CCMI 885 to prevent B. bruxellensis ISA 2211 growth and 4-ethylphenol production in synthetic and true grape must fermentations. Results showed that B. bruxellensis growth and 4-ethylphenol production was significantly inhibited in both media, although the effect was more pronounced in synthetic g...
Ciência e Técnica Vitivinícola, 2021
The present work was aimed at understanding the sensory responses induced by dry white wine modif... more The present work was aimed at understanding the sensory responses induced by dry white wine modified with increasing concentrations of different sensory active molecules. The tasting panel was composed by 34 trained subjects characterized according to gender, smoking habits, 6-n-propylthiouracil (PROP) taster status, and sensitivity to tartaric acid, tannic acid and sucrose. Additional taste/mouthfeel responsiveness was evaluated in a basal white wine added of tartaric acid, tannic acid and sucrose. The addition of a fruity odorant mixture to the base white wine enabled the assessment of orthonasal aroma and taste intensities (sweetness, sourness, saltiness). The diversity of taste/mouthfeel responsiveness in water or wine enabled to group individuals as high or low sensitives. Likewise, the tasting panel showed two groups responding differently to aroma and flavor. Both high and low aroma sensitivity individuals showed equal (p>0.05) and congruent response to in-mouth sweet flav...
Foods, 2020
The conventional method for the sensory evaluation of wine is based on visual, olfactory and gust... more The conventional method for the sensory evaluation of wine is based on visual, olfactory and gustatory perceptions described by a domain-specific language. This is a complex task, requiring extensive training, which is not feasible from a consumer perspective. The objective of this study was to apply a wine tasting sheet, including sensory and emotional responses, to simplify the recognition of fine white wines by consumers. First, a panel of 15 semi-trained judges evaluated eight sensory attributes through Optimized Descriptive Profile (ODP) methodology. Then, a group of 104 consumers evaluated five white wines with different sensory characteristics using an improved emotional wine tasting sheet. The emotions and sensations most frequently associated with white wines were obtained through the Check-All-That-Apply (CATA) approach. The eight sensory attributes were significant (p-value < 0.05) in the distinction of wines by the ODP. Likewise, the distinction of the wines also prov...
Biology, 2021
In the city of Maputo, Mozambique, food and water are often sold on the streets. Street water is ... more In the city of Maputo, Mozambique, food and water are often sold on the streets. Street water is packaged, distributed, and sold not paying attention to good hygienic practices, and its consumption is often associated with the occurrence of diarrheal diseases. Coincidentally, the increase of diarrheal diseases promotes the inappropriate use of antibiotics that might cause the emergence of antibiotic-resistant bacterial strains. In this context, the present study aimed to assess the microbiological quality of water sold on the streets of Maputo, as well as the antibiotic resistance profile of selected Enterobacteriaceae isolates. The 118 water samples analyzed were from street home-bottled water (n = 81), municipal water distribution systems (tap water) (n = 25), and selected supply wells in several neighborhoods (n = 12). The samples were analyzed for total mesophilic microorganisms, fecal enterococci, fecal coliforms, Escherichia coli, and Vibrio spp. The results showed a high leve...
Journal of Food Research, 2013
Aims: This work was aimed at the evaluation of several sanitation procedures on the reduction of ... more Aims: This work was aimed at the evaluation of several sanitation procedures on the reduction of total microbial flora and of D. bruxellensis recovered from the inner layers of the barrique’s wood. Methods: A group of used oak barrels tainted by 4-ethylphenol and contaminated with D. bruxellensis were differently sanitized and, afterwards, were dismantled to analyse samples of shaves taken from wood surfaces at different depths. Microbial counts were obtained by the Most Probable Number Technique using broths of general purpose medium and of Dekkera/Brettanomyces differential medium (DBDM). Results: The least inefficient treatment included barrique steaming at low pressure. Uncontaminated samples were only detected under this treatment and in the upper level (0-2 mm) of the staves. With this treatment complete destruction of the contaminating flora was not achieved in any level of stave side surfaces and in grooves. The presence of D. bruxellensis was detected in depths up to 6-8 mm...
Understanding and Measuring the Shelf-Life of Food, 2004
International Journal of Food Microbiology, 1997
The long-chain fatty acid composition of yeast strains was determined for several species associa... more The long-chain fatty acid composition of yeast strains was determined for several species associated with the wine industry. The Saccharomyces cerevisiae, Zygosaccharomyces bailii, Saccharomycodes ludwigii, Schizosaccharomyces pombe, Brettanomyces /Dekkera spp., Pichia anomala, Pichia membranaefaciens and Lodderomyces elongisporus species presented distinct fatty acid profiles after multivariate statistical analysis. The Zygosaccharomyces rouxii species showed profiles similar to Zygosaccharomyces bailii. The use of fatty acid profiling in wine bottling plants and wines makes it possible to trace the origin of the strains responsible for spoiling the final product. In one case the origin was found at the outlet of the finishing filter and identified as Zygosaccharomyces bailii. In the other case the source of contamination was discovered in the heads of the filling machine and assigned to the Pichia membranaefaciens species. The results point out the discriminating power and the industrial applicability of the technique described in this work to analyse yeast long-chain fatty acid compositions.
International Journal of Food Microbiology, 2000
The evolution of the yeast flora was studied for an artisanal semi-hard ewes' cheese made from ra... more The evolution of the yeast flora was studied for an artisanal semi-hard ewes' cheese made from raw milk. Mean log 10 yeast counts per gram of cheese body ranged from 2.7 to 6.4, with the higher counts observed after a ripening period of 30 days. The yeast population decreased thereafter and, at the end of curing process, reached values similar to those of the beginning. A total of 344 yeasts strains were randomly isolated from the curd and cheese body during the 60 days long ripening period. Esterase activity was common to almost all isolates (98%) while proteolysis was observed in 12% of the total yeast population. The proportion of strains with positive glucose fermentation increased from 21% in the curd to 75% at the end of the ripening period. A total of 150 isolates representative of the physiological characteristics tested were examined with the API ID 32C system showing different degrees of quality of identification. Only 15% of the strains (23 isolates) were excellently identified being assigned to the species Candida zeylanoides. The most frequent species appeared to be Debaryomyces hansenii (anamorph Candida famata) and Candida intermedia. These two species amounted to 9% of the 31 yeasts in the curd increasing to 86% at the end of the ripening period.
International Journal of Food Microbiology, 1997
The inhibition kinetics of fermentation by Z~Rt~.'Lt"~harorn~~~s builii and Srrcchnromyces cerevi... more The inhibition kinetics of fermentation by Z~Rt~.'Lt"~harorn~~~s builii and Srrcchnromyces cerevisine were evaluated fol weak carboxylic acids. Several regression equations were tried to fit the experimental data, most cases being best fitted to exponential curves. The following parameters were determined: i) acid concentration responsible for 50% inhibition of fermentation (C,,,,A); ") 11 area under the regression curve up to that concentration (A,,,,) and iii) exponential inhibition constant (k,). These paramctcrs wcrc compared according to their ability to express the inhibitory effect of each acid. In broad terms, the values of k, in association with minimum inhibitory concentrations (x
Fermentation
Winemaking involves a wide diversity of microorganisms with different roles in the process. The w... more Winemaking involves a wide diversity of microorganisms with different roles in the process. The wine microbial consortium (WMC) includes yeasts, lactic acid bacteria and acetic acid bacteria with different implications regarding wine quality. Despite this technological importance, their origin, prevalence, and routes of dissemination from the environment into the winery have not yet been fully unraveled. Therefore, this study aimed to evaluate the WMC diversity and incidence associated with vineyard environments to understand how wine microorganisms overwinter and enter the winery during harvest. Soils, tree and vine barks, insects, vine leaves, grapes, grape musts, and winery equipment were sampled along four seasons. The isolation protocol included: (a) culture-dependent microbial recovery; (b) phenotypical screening to select fermenting yeasts, lactic acid, and acetic acid bacteria; and (c) molecular identification. The results showed that during all seasons, only 11.4% of the 14...
Heritage, Apr 2, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Fermentation, 2022
The production of wines using ancient techniques is a present trend with commercial interest amon... more The production of wines using ancient techniques is a present trend with commercial interest among consumers valorising their historical background. Therefore, the objective of the present work was to recreate wines and piquettes produced from dehydrated grapes, vinified according to the techniques described in classical Roman agricultural manuals. Muscat of Alexandria grapes were harvested and subjected to greenhouse drying under ambient temperature for 7 days, during the 2020 and 2021 harvests. When weight loss was approximately 30%, grapes were processed according to different protocols, including a rehydration step using saltwater or white wine (2020 harvest). Fermentation was conducted with the addition of commercial yeast without sulphur dioxide supplementation. The piquettes were obtained from the pressed pomaces diluted with water solution (5 g/L tartaric acid). The 2020 wines showed alcoholic content and residual sugar ranging from 14.8 to 17.0% (v/v), and 0.8 g/L to 18 g/L...
Beverages, 2022
The purpose of this review is to provide a general description of ancient winemaking techniques a... more The purpose of this review is to provide a general description of ancient winemaking techniques and wine styles that were most lauded in antiquity, in support of their revival and dissemination today. From the first fully excavated winery, dating from the late fifth to the early fourth millennium BC, the gentle crushing of grapes by foot and the probable absence of maceration indicate that most wines were made with the aim of reducing astringency. The oxidative nature of winemaking would have resulted in rapid browning, so that wines made from red grapes would have had a similar color to those made from white grapes after being aged in clay vats for several years. The difficulty in preventing the wine surface contact with the air would have resulted in biological ageing under the yeast pellicle being a common occurrence. This phenomenon was not considered a flaw, but a characteristic feature of highly prized wines. Dried grapes were used to make sweet wines, which were also highly p...
International Journal of Food Microbiology, 2012
Grapes have a complex microbial ecology including filamentous fungi, yeasts and bacteria with dif... more Grapes have a complex microbial ecology including filamentous fungi, yeasts and bacteria with different physiological characteristics and effects upon wine production. Some species are only found in grapes, such as parasitic fungi and environmental bacteria, while others have the ability to survive and grow in wines, constituting the wine microbial consortium. This consortium covers yeast species, lactic acid bacteria and acetic acid bacteria. The proportion of these microorganisms depends on the grape ripening stage and on the availability of nutrients. Grape berries are susceptible to fungal parasites until véraison after which the microbiota of truly intact berries is similar to that of plant leaves, which is dominated by basidiomycetous yeasts (e.g. Cryptococcus spp., Rhodotorula spp. Sporobolomyces spp.) and the yeast-like fungus Aureobasidium pullulans. The cuticle of visually intact berries may bear microfissures and softens with ripening, increasing nutrient availability and explaining the possible dominance by the oxidative or weakly fermentative ascomycetous populations (e.g. Candida spp., Hanseniaspora spp., Metschnikowia spp., Pichia spp.) approaching harvest time. When grape skin is clearly damaged, the availability of high sugar concentrations on the berry surface favours the increase of ascomycetes with higher fermentative activity like Pichia spp. and Zygoascus hellenicus, including dangerous wine spoilage yeasts (e.g. Zygosaccharomyces spp., Torulaspora spp.), and of acetic acid bacteria (e.g. Gluconobacter spp., Acetobacter spp.). The sugar fermenting species Saccharomyces cerevisiae is rarely found on unblemished berries, being favoured by grape damage. Lactic acid bacteria are minor partners of grape microbiota and while being the typical agent of malolactic fermentation, Oenococcus oeni has been seldom isolated from grapes in the vineyard. Environmental ubiquitous bacteria of the genus Enterobacter spp., Enterococcus spp., Bacillus spp., Burkholderia spp., Serratia spp., Staphylococcus spp., among others, have been isolated from grapes but do not have the ability to grow in wines. Saprophytic moulds, like Botrytis cinerea, causing grey rot, or Aspergillus spp., possibly producing ochratoxin, are only active in the vineyard, although their metabolites may affect wine quality during grape processing. The impact of damaged grapes in yeast ecology has been underestimated mostly because of inaccurate grape sampling. Injured berries hidden in apparently sound bunches explain the recovery of a higher number of species when whole bunches are picked. Grape health status is the main factor affecting the microbial ecology of grapes, increasing both microbial numbers and species diversity. Therefore, the influence of abiotic (e.g. climate, rain, hail), biotic (e.g. insects, birds, phytopathogenic and saprophytic moulds) and viticultural (e.g. fungicides) factors is dependent on their primary damaging effect.
In our work we assessed the possibility of using fatty acid analysis for the distinction of three... more In our work we assessed the possibility of using fatty acid analysis for the distinction of three groups of spoilage wine yeasts, the film-forming (e.g. Candida vini, Pichia membranaefaciens), the fermenting (S. cerevisiae) and those of more difficult control, the spoilage yeasts «sensu stricto» (e.g. Z. bailii, Saccharomyces ludwigii). The methodology of Kock et al. is suitable for this differentiation, but in industrial terms is neither practical nor rapid enough. In order to decrease the response time, and simplify the growth procedures, another technique using solid medium was tried, in which growth takes two days
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Papers by Manuel Malfeito Ferreira
From the Foreword "We read about critics who claim to identify in blind tests the producer and vintage year of wines from a certain region. Therefore, we feel inadequate-do we even have what it takes to appreciate great wine? This new book, written by two highly respected university professors, Manuel Malfeito Ferreira and Virgílio Loureiro, promises to put the fun back into wine tasting. The book is full of historical, scientific, and practical information that will appeal to any wine lover. Most of all, the authors demystify wine tasting and propose a new approach that everyone can follow. This approach shuns the use of numerical metrics or the need to cultivate poetry skills to describe what is in our glass. [...] I find myself going back to this book, always discovering new insights about wine appreciation. Like a great wine, this book improves with time and leaves a lasting impression."