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New World Wine Maker Blog

The Relationship Between Sensory Characteristics and Emotion in Consumer Wine Preferences

Consumer wine preference is an oft-studied topic, as understanding wine preference is paramount in determining how to market and sell any given wine.  It can also help wine marketers not only observe what consumers like, but also how these preferences can change over time and between different segments.

Often, wine preference is determined via the hedonistic scale, or how much a consumer says they like a particular style of wine. However, research in food and other industries have found that the role of emotions may provide an extra level of understanding in regard to consumer preferences and that this type of analysis may be very useful in wine as well. For example, studies have found many associations between certain flavor types and emotions in various foodstuffs: in dark chocolate, studies have linked “powerful” and “energetic” with cocoa flavor; and in beer, studies have linked herbal flavors with “sadness” and citrus flavors with “disappointment.

According to the authors of a new study, available online in late December 2017 and to be published in print in June 2018 in the journal Food Quality and Preference, there have been no studies linking specific wine sensory characteristics with emotional responses, nor is there a dedicated lexicon for such relationships in wine products like there are with food (i.e. the EsSense Profile). In this new study, the researchers aimed to analyze the associations between sensory characteristics of wine and elicited emotional responses of consumers, further subcategorized by gender and age.

Brief Methods

This study had two parts:  a sensory evaluation of the wines by a trained panel (11 total: 5 women, 6 men; faculty and researchers from the School of Agricultural, Food and Biosystems Engineering at the Universidad Politécnica de Madrid in Spain), and a consumer evaluation of the wines with an additional emotional response analysis.

6 commercially-available wines were used in the study: 2 whites, 1 rosé, and 3 reds.

For the sensory evaluation by the trained panel, each wine was scored for various aromatic and sensory attributes using an unstructured 15-cm line scale that had labels “low” and “high” on the ends (with variation throughout the line that could be translated to a specific intensity level of any given attribute).  Wines were presented in random order.

For the consumer evaluation, participants were first asked to complete questionnaires on demographics and wine consumption habits. Next, they participated in a “warm-up” or “practice” tasting session with 7 wines presented [blind] at the same time.  Finally, after the warm-up, they were presented with the sample of 6 test wines briefly mentioned above.

After tasting the wines (which were presented in random order), participants were asked to rate their liking of each wine (using a 9-point hedonic scale), and what emotions were elicited by each wine (using the EsSense 25 software). Emotions were rated using a 10-cm line scale with the labels “very low” and “very high” at the ends (and everything in between).

Participants were recruited from the School of Agricultural, Food and Biosystems Engineering at the Universidad Politécnica de Madrid and were required to consume wine at least once per month. A total of 208 people participated in the study (48.5% male, 51.5% female).  Participants were categorized by three age groups (for studying potential age effects): young adults (18-35 years old; 44.9% of the total); middle-aged adults (36-55 years old; 29.3% of the total); and older adults (55 years old and older; 25.9% of the total) …

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What do I smell?

This has often been slurred after one to many glasses of Chardonnay has been gulped down or heard whilst serving a guest who for the fifth time has not heard you explain that you’ve served them a 2011 Syrah. It may seem like one of those completely obvious questions with the answer simply being: you are smelling wine. It still remains a standing joke in lecture halls when we have our tasting practicals for someone to pipe up that it seems to in fact be white wine in the glass in front of us.

For those who like to dive deeper into the glass and deeper into thought the answer is for more fantastical and complex.

First let’s look at some biology and how the sense of smell works (this is a Crip notes version by an oenology student not a biologist). Flavour molecules slowly evaporate off the exposed area of the wine; these molecules are then inhaled when you sniff the wine. Inside your nose are receptor sites which the molecules are ‘bound’ to. The receptor then sends off an electrical signal that is received by the olfactory bulb and translated and sent off to the olfactory cortex which then interprets the smell of the compounds.

Never be upset when the more advanced taster finds more flavour’s than you in the wine. The more practice you get the more you will be able to differentiate between the different molecules and the more your olfactory cortex will be able to remember that this smell is elderflower rather than just a floral aroma.

The flavours we taste in wine are broken into primary, secondary and tertiary. Primary flavours are derived straight from the grape, some are precursors to flavonoids that evolve during fermentation and others are evident in the final product. These would include your berries and grassy/green notes. Secondary flavours are developed during fermentation; the primary precursors are bound with other ions and evolve into complex aroma characteristics such as volatile thiols and terpenes. These would be the tropical fruit aromas you can identify. Tertiary flavours are developed during maturation in the bottle, on the lees or in the barrel, allowing for smoother wines, cooked fruit, wooden flavours and rising bread.

Let’s go on a journey to illuminate the vastly unknown territory of flavour compounds:

Floral varietals such as Muscat, Gewürztraminer and Riesling contain monoterpenes such as linalool which can be perceived as orange blossom or lavender.

Fruity aromas that can be identified in most young wines are given off by esters. Esters are present in two different forms: Ethyl esters and acetate esters. Ethyl esters are formed during the enzymatic reaction between alcohol and acetic acid. An example of an ethyl ester is ethyl hexonate that gives rise to aroma characteristics such as stone fruit, strawberry, liquorice and green apple. Acetate esters are formed during amino acid metabolism and containing an acid group and a higher alcohol group. South Africa’s very own cultivar Pinotage can sometimes be guilty of having an over baring concentration of the acetate ester: Isoamyl acetate which gives off that infamous banana flavour.

 

Green and grassy aromas that you either love or love to hate in Sauvignon blanc, Cabernet sauvignon, Cabernet franc and many other cultivars. These can be given off by compounds called methoxypyrazines. Methoxypyrazines are secondary products of amino acid metabolism and are nitrogen containing compounds.  There are three major methoxypyrazines that have been identified: Isobutyl-Methoxypyrazines which give off bell pepper and cape goose-berry flavours, Isopropyl-methoxypyrazines which gives some Sauvignon blancs and semillions that cooked/pickled asparagus flavour, and secbutyl-methoxyoyrazines which also gives off green aromas.

 

Mouth-watering tropical fruit that make wines a bit too easy drinking are formed by volatile thiols. The three most predominant and evident in wines are 3-MH, 3-MHA and 4MMP, they are formed during fermentation by binding precursors to sulphur molecules. Aromas such as granadilla, guava, grapefruit, boxwood and gooseberry are given off by these molecules. They are very evident in Sauvignon blanc, Chenin blanc and Chardonnay.

 

Now that we have more of an understanding of what we smell it’s important to remember some simple tips to improve your tasting profile. Firstly, a sip or two is more than enough per wine in order to taste it, judge it and see if you love it. Secondly spitting is not gross, it is necessary in order to be able to taste every wine and remain a good level of sobriety toward the end of the tasting. Thirdly, have a designated tasting notes book, it may be hard to recall a specific wine from that tasting at that place that one time, so it’s great to have a reference. Lastly if you would like to expand your taste buds, don’t simply refer to the red fruit you smell in the pinot noir, elaborate: Is it fresh, cooked or cured? Is it a sour cherry or a sweet strawberry? Try and be as specific and elaborate as possible, it will also make it easier to identify a wine you have tasted before.

Happy tasting!

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Meet Norman Ketelo – Winemaker at De Grendel

Q When and where  were you born ? 

“I was born at Lady Frere in the Eastern Cape on 1st March 1875.”

Q Where did you study ?

“ I have no formal education in winemaking but started in the industry as a cellar hand with Charles Hopkins at the Graham Beck cellar in Franschhoek. While there I did Skop 1,2 and 3 and achieved “Circle of Excellence”. “In 2004 I moved to Meerendal but in 2005 Charles Hopkins invited him to join the new cellar at De Grendel.”

Q. Do you consider your approach to winemaking to be different to others ?

After some careful thought. “I think I am pretty much set in the way I have been taught so I guess what I make is in the cellar style so it is different to others. However, I am always prepared to learn  and put into practice what might improve my winemaking.”

Q. How involved do you get in the vineyard ?

“I suppose not as much as I should but then we have expert viticultural people. However I worked an entire year, 2000 in the vineyard at Bellingham and got to appreciate just how important it is to understand the vineyard.”

Q. Do you have any varieties you prefer to work with ? 

“That is difficult to answer as every variety presents it’s own challenges  and rewards.  I think that Merlot and Sauvignon blanc would be my favourites.”

Q. Have you been influenced by a particular winemaker or region ? 

“Obviously Charles Hopkins has been a huge influence in my understanding of wine. He also took me on a visit to Burgundy which was my first overseas winemaking experience. This will always stand as a major influence in my development.”

Q. What would you consider your greatest achievement as a winemaker ?

“I havn’t got there yet. To me everything is still an on going learning experience.”

Q.  What “secrets” have you “developed” that makes your wines different to others ?

“No, not really but I am a great believer in terroir  and I ensure I am guided by that total concept.

Q. How important is modern winemaking equipment in your winemaking ?

“The equipment is very important and plays a major part in the efficiency but it is the grape that is the most important thing.”

Q. What would your dream be for the future ?

“Wow, my greatest dream would be to be winemaker in my own cellar !”

Q. Any other thoughts ? 

“I find it strange that my Dad worked most of his life with Douglas Green in their security and then I became a winemaker working my way up from a cellar hand.  It goes to show that if you can motivate yourself and develop nothing can stop your progress.”

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Can yeasts be used to prevent protein haze?

Winemakers add bentonite to prevent protein haze in white wines. Although this treatment reaches its goal, it also leads to volume losses and sometimes a decrease in wine quality. The question is: are there alternatives available?

Protein haze – some background information

The removal of proteins is a key step during the production of white and rosé wines to avoid the possible appearance of a harmless, but unsightly haze. Haze formation is an aesthetic problem that consumers usually regard as a fault (e g microbial spoilage) leading to potential economic losses. Proteins that are responsible for haze formation in wine have been identified as pathogenesis-related proteins of grape origin. The most abundant class of haze-forming proteins are chitinases and thaumatin-like proteins and are continuously produced in the grape berry and even more so in response to pathogen attack. Because of their physical structure and properties, these proteins are very resilient and are not or poorly degraded during the course of fermentation. Over time and upon exposure to warm/hot temperatures during storage for instance, these proteins denature and aggregate into light dispersing particles resulting in what is referred to as ‘haze’.

The mechanisms of haze formation has received much attention from researchers over the last decade. It is complex by nature and depends on several factors, one of the most important being the presence of sulphate. The removal of these proteins is usually achieved via bentonite fining, but several issues including volume loss, aroma stripping and sustainability have been identified with the use of this clay. Several strategies have therefore been investigated over the past few years. One of the most attractive alternatives would consist in degrading these haze-forming proteins with enzymes. This is particularly appealing since enzymatic degradation of proteins (protease activity) would not lead to any of the issues mentioned for bentonite and could have the additional benefit of releasing yeast assimilable nitrogen.

Where does one find enzymes capable of degrading haze-forming proteins? …

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An insight to wine making you may not have heard before

You may imagine walking through the vineyards in the early morning light, picking a plump grape off a bunch , looking at its colour, admiring its bloom, pinching it slightly to see how easily the pulp emerges from the skin. The juice crisp and clean to taste and the pip slightly tannic as you bite down on it. The cool atmosphere of the barrel cellar with that earthy wooded smell as you taste a voluptuous shiraz that has been maturing for the last 3 years. The neat promenade of tanks, clean and lined up, awaiting harvest. Yes this may be what you imagine everyday wine making is like, quiet and romanticized.

You may have a more clinical idea, silver labs and weighing boats, refractometers, thermometers and pH meters all in the correct position awaiting calculation. Beakers lined up neatly, reeking of a food safe disinfectant. The store room, tool room and Chemical storage room all fill and perfectly organized, simply awaiting use. All the pipes not in use, simply out of sight until needed. Yes a perfectly sterile environment that never smells of anything but disinfectant and the slight reduction coming of a miss behaving tank. This may be your idea of a working cellar more a laboratory than a cellar.

Well even though some of these elements may appear in the everyday habits of a winemaker, this is not the only part to it. No one seems to talk about the scrub work that needs to be done every day so that you can sit on your easy chair and enjoy that lovely Chardonnay.

Firstly winemakers cannot sleep in, the early mornings are the best time to taste the grapes and take accurate samples. The sample grapes need to be randomly selected and collected which requires a lot of walking, don’t think you can just take 10 bunches from one vine!  Those grapes then need to be crushed, the juice settled and then tested for acid, sugar and pH. The juice should also be tasted to see aroma expression. These results all have to be recorded, nothing can be forgotten or left out. This process is repeated twice a week for 4 weeks before the grapes come in.

Speaking of the grapes coming in, all machinery that comes into contact with the grapes must be washed and disinfected, all the nuts and bolts need to be greased with food grade grease, the wires need to be checked and the mechanism must be running smoothly.

The whole cellar should be cleaned (sustainable farming), from top to bottom to ensure no weird flora or yeast are hanging around to contaminate the grapes coming in. Scrubbed from the ceiling to the floor – including the outsides of the tanks and barrels.

The barrels needed for the new vintage need to be emptied into tank,  that wine then needs to be filtered and bottled which is an ordeal. The Barrels then need to be checked, marked, rinsed and transported to a facility where they burn sulphur inside the barrel to sterilize it. All transport of barrels needs to be done with a forklift because even an empty barrel is pretty heavy. The barrel cellar then needs to be rearranged with the wines still maturing moved to the back with the new barrels in front.

The pipes that are so neatly tucked away need to be washed thoroughly inside using a foam ball and a closed system of water. Even though the pipes are hollow, they are really heavy! A team of 3 is needed to move a 20m long pipe.

All aerators and pressure releasers need to be cleaned out and checked for rust. Any equipment that comes into contact with the grapes, juice or wine should be sterile!

The chemical store that’s so neat and accessible?  A stock take needs to be done and every batch number and expiry date has to be checked and new products ordered and packed. The tool store needs to be cleaned out, broken things thrown away, miscellaneous clutter disposed of and replacements bought.

This described a mere two days of the build up to harvest, its brutal and hectic and invigorating. When you step into a cellar again, remember all the nitty gritty things that need to be done before the grapes can be bought in or the wine can be made. There are the romantic parts, the scientific parts, and the other work that just has to be done. It all intertwines into this beautiful tapestry that is the art of winemaking. Being actively involved in this industry means you have to do each part, and I wouldn’t have it any other way.

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TAKE A BIG WHIFF!

One of the most important parameters for the measurement of quality is the aroma/flavour profile of a wine (1). Up till now, more than 1000 compounds have been identified in grapes and wine. To add to the complexity of the wine matrix, the individual concentrations of these compounds may vary considerably (2). The aroma profile will also be influenced by production processes, be it in the vineyard or cellar and with an infinite number of variations possible in the production process, the final aroma profile of a wine is a complex matter to say the least (3).

There are various influencing factors that play a role in determining wine aroma composition. These include, amongst many more, climatic conditions (e.g. altitude above sea level), viticultural practices (e.g. canopy management) and enological practices, e.g. fermentation conditions, on which this article will focus (1).

Even though some aroma impact compounds exist for some varieties, seldom can the sensory perception of wine aroma be attributed to a single compound (1). The aroma attributes of a specific compound depends not only on its concentration or the specific odour threshold value (lowest concentration at which it can be detected), but also its interaction with other aroma compounds, be it the enhancement (even compounds present below their odour threshold) or suppression of another compound (1). Because of the complexity of the wine matrix it is almost impossible to predict the interaction between aroma compounds, but certain actions, like the selection of a specific yeast strain, could aid in driving the aroma profile to a certain extent (2). This is an important tool as it has been shown that a difference in flavour profile solely as a result of the choice of yeast strain, can be detected not only by trained panels and wine professionals, but more importantly, wine consumers (6). This implies that besides choice of viticultural practices and grape selection, selecting a specific yeast strain (usually Saccharomyces cerevisiae) for fermentation, as well as a bacteria strain for MLF, can greatly modify the aroma, flavour, mouthfeel, colour and chemical complexity of a wine, making this a tool to create a specific flavour profile according to market specifications (3).

The compounds that play a role in wine appearance, aroma, flavour and mouthfeel can be derived from three sources: the grapes, microbial modification during fermentation and then maturation, be it bottle ageing or wood maturation (3).

Grape-derived compounds do not only provide the basic wine structure, but also results in distinct varietal characteristics (3). The main grape-derived aroma compounds belong to the groups of monoterpenes, norisoprenoids and methoxypyrazines. Some examples of these include rose-like geraniol in Chardonnay, spicy eugenol and guaiacol in Gewürztraminer and floral, fruity and berry-like β-damascenone and violet-like β-ionone in Cabernet Sauvignon, Shiraz and Pinotage (6). While monoterpenes and norisoprenoids are very important in Muscat and aroma-rich varieties, fermentation-derived aroma compounds play a larger role in ‘neutral’ cultivars. The following section will focus on yeast-derived fermentation aroma compounds, although MLF also makes a significant contribution towards the final wine aroma profile.

While the main purpose of yeast is to metabolise sugar in order to produce ethanol and carbon dioxide, this microbial culture also produces a myriad other metabolites that, despite being present in small amounts, significantly alters the wine aroma profile and have a significant sensorial impact (3). Yeast strains are able to modify the wine aroma via three mechanisms (3):

1) via the extraction of compounds from solids in the grape must;
2) modification of grape-derived aroma compounds and
3) producing flavour-active metabolites.

The biosynthetic pathways responsible for aroma production via these mechanisms are influenced by various factors, to name a few (3):

  1. a) viticultural factors;
  2. b) composition and pH of grape must;
  3. c) nature and prevailing temperature of grape must and
  4. d) technological aspects and vinification methods.

As previously mentioned, the yeast can modify grape-derived aroma compounds for e.g. esters, higher alcohols and lactones in Chenin blanc contributes to varietal aroma; mercapto components formed during fermentation in Sauvignon blanc adds to passion fruit, guava and other tropical aromas and iso-amyl acetate adds to banana aromas in Pinotage (6). The table below also lists some of the most important yeast-derived aroma compounds important in determining the final wine aroma profile that serves as an important quality parameter (5).

Major aroma impact compounds produced and modified by yeast during fermentation

Volatile Acids
  • produce 0.2-0.7 g/L acetic acid during fermentation
Alcohols
  • ethanol: influence volatility of other aroma compounds
  • higher alcohols: positive or negative effect on wine aroma
  • involves degradation of amino acids
Carbonyl Compounds
  • acetaldehyde: 10-75 mg/L produced (bruised apple; oxidation)
  • diacetyl: small amount (0.2-0.3 mg/L) produced by yeast (butter )
Volatile Phenols
  • off-odours: medicinal, barnyard
  • vinyl-phenols: stabilise colour in red wine
  • Brettanomyces: ethyl-phenol (negative sensory impact)
Esters
  • influence fruity and floral aromas
  • dependant on: yeast strain, fermentation temp., precursors
  • acetate esters: ethyl acetate (fruity); iso-amyl acetate (banana, pear); 2-phenylethyl acetate (honey, rose, flower)
  • ethyl esters: ethyl hexanoate and ethyl octanoate (apple
Volatile Sulphur Compounds
  • low sensory threshold (generally negative to wine quality)
  • positive: thiols (grape-derived compounds modified by yeast)
  • guava, passion fruit, grapefruit, gooseberry (Sauvignon blanc)
  • release and modification is yeast strain dependant
Monoterpenes
  • grape-derived: aromatic (free) and non-aromatic glucose-bound
  • free form: fruity and floral
  • yeast release bound form via β-glucosidase activity; add to aroma

 

It has also been shown that chemical changes that occur as a result of ageing, either bottle or wood, may also alter the wine composition and quality (1). During the ageing period, compounds are extracted from wood (oak lactones) and these add to aroma complexity. Certain compounds are also transformed and/or liberated from bound forms, which mean they can then play a role in the aroma perception of the wine.

Due to the fierce competition in the wine industry, wine producers are being forced to investigate and understand consumer preferences and expectations and produce wine accordingly. This has become a market-driven industry whereby winemakers are challenged with responding to consumer sentiments and preferences (3). One of the tools in a winemaker’s arsenal that is available to address this challenge is the selection of the microbial populations that will be responsible for fermentation. Therefore the yeast and bacteria strain(s) can be seen as a flavour-impact tool to produce a certain style of wine. This will only be possible with an understanding of the impact aroma compounds and the role the selection of the correct yeast and bacteria can play in the production and or modification of these compounds. This is the reason for the extensive and careful research that goes into the development of all Anchor yeast and bacteria cultures. This way we ensure not only optimal fermentation, but also optimal contributions to the final aroma profile.

So take a big whiff…

References:
1. Wine aroma-important aspect of wine quality. www.newworldwinemaker.com
2. Sensory perception. www.newworldwinemaker.com
3. Swiegers J.H., Bartowsky E.J., Henschke P.A. & Pretorius I.S., 2005. Yeast and bacterial modulation of wine aroma and flavour. The Australian Journal of Grape and Wine Research, 11, 139-173.
4. The complete A-G understanding to waking up your wine. www.newworldwinemaker.com
5. The impact of yeast on the sensory quality of wine. www.newworldwinemaker.com
6: Cordente A.G., Curtin C.D., Varela C. & Pretorius I.S., 2012. Flavour-active wine yeasts. Applied Microbiology and Biotechnology. DOI 10.1007/s00253-012-4370-z

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