Sensory methodology 1 Descriptive analysis (DA)

Training

Heymann, 2010). A total of 10 sessions of two hours each with a 10-minute break after an hour was used for training. The panel attended three training sessions per week over four weeks. During the first two sessions all the wines of the specific product set were presented. The judges were instructed to generate as many attributes as they wanted to describe the sensory space highlighting similarities and differences between the samples. Reference standards were prepared from the consensus list of attributes obtained during the first two sessions. The wines and reference standards were presented to the panel. They could evaluate the reference standards and make new suggestions to better describe the attributes where necessary. During the next three sessions consensus on the attributes was achieved and the list of attributes was reduced and finalised (Table 2). The order in which the panel preferred to rate the attributes and the anchors of the scale were established. Rating of the attributes on an unstructured 10 cm line scale anchored at “none” to “intense” were practised and consensus were reached after three sessions.

55 TABLE 2.

Aroma reference standards presented during DA training representing the final attribute lists.

Descriptor Reference standard Amount

Chenin Blanc wines

Pineapple Pineapple (fresh) 2 - 4 cm2 _piece

Peach / apricot Peach (fresh) 4 - 4 cm2 _piece

Citrus Lemon, orange and grapefruit peel 2 - 2 cm2 _{piece of each}

Paw-paw Paw-paw (fresh) 3 - 4 cm2 _piece

Passion fruit Passion fruit (fresh) 4 pips and a 1cm2 _{piece of skin}

Stewed dried fruit Cooked dried fruit (Safari) 1 dried apple, ½ prune, ½ dried peach, 1 dried pear

Honey Acacia honey (Lune de Miel) 15 mL

Orange marmalade Seville marmalade (Rhodes) 5 mL

Caramel / burnt sugar

Caramel syrup (St. Dalfour) 20 mL

Buttery toffee Soft toffees (Toff-o-lux) 1 toffee in boiling water

Oaky Medium toasted French oak chips (NT Bois,

RX South Africa)

2 g

Cooked veg Canned vegetable brine 10 mL canned bean brine (Rhodes), 10 mL

canned asparagus brine (Goldcrest), 10 mL artichoke brine (Goldcrest)

Flinty / mineral Flint stone 2 flintstones struck against each other

Floral Honeysuckle essence (Ferminich) 5 drops on cotton wool

Green pepper Green pepper (fresh) 2 cm2

Litchi Litchi (canned, KOO) 1 litchi and 10 mL syrup

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the unstructured 10 cm line scale provided that was anchored at “none” to “intense”. The attributes were listed on the tasting ballot in the order presented in Table 2. The panel evaluated the entire sample set three times on one day. Ten-minute breaks were enforced between the replicates. A monadic sample presentation procedure, presenting one sample at a time was followed.

3.2.3.2 Check-all-that-apply (CATA)

A pre-determined list of terms compiled from data obtained in previous studies (Campo et al., 2008; Campo et al., 2010; Bester, 2011; Hanekom, 2012; Van Antwerpen, 2012) and the help of industry professionals, were provided. The list was constructed to span the sensory space of South African Chenin Blanc wines. Only sensory attributes were used, no quantifiers, e.g. “high”, “medium”, “very”, hedonic or emotional terms or phrases were used. Sensory judges were asked to choose the three to five attributes from the list that best described the sensory characteristics of that specific sample. They were given the option to provide terms that were not on the list if they found the list insufficient. Samples were presented according to a monadic serving protocol, one at a time. This list was used for RATA, and during the verbalisation steps of the free sorting task and the PM exercise.

3.2.3.3 Rate-all-that-apply (RATA)

RATA was performed by first performing CATA followed by a second step where the intensities of the attributes selected were rated on an unstructured 10 cm line scale anchored at “none” to “intense”. Samples were presented according to a monadic serving procedure, one at a time.

3.2.3.4 Free sorting

During the free sorting task all the samples were presented simultaneously. The judges were asked to group samples with similar sensory characteristics together according to their own criteria. They could group as many samples together as they deemed necessary, creating at least two groups and grouping at least two samples together in one of the groups. In other words, each sample could not be in its own group and all the samples could not be in the same group (Chollet et al., 2011).

To explain the categorisation/grouping of the samples a “labelling” (Bécue-Bertaut & Lê, 2011) or “verbalisation” (Chollet et al., 2011) step followed where judges had to provide three to five terms per group. These descriptors had to be chosen from the provided list of attributes to simplify the task of the sensory judges, the data analysis (Lelièvre et al., 2008) and achieve uniformity between the procedures used for the different sensory methods. No quantifiers such as “very”, “medium” or “high” were provided or allowed.

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3.2.3.5 Napping

The specific restricted version of projective mapping (Risvik et al., 1994, 1997; Pagès, 2003, 2005) called Napping was carried out using 60 x 40 cm white paper sheets in the “landscape” orientation. Sensory judges received all of the samples simultaneously.

Judges had to place similar samples close to each other and different samples far apart marking the desired positions of the samples with the sample’s three-digit code and an X on the white paper sheets. Sticky “Post-it” paper notes were provided to judges to make notes on and stick to the wine glasses to reduce the difficulty of the task of remembering the sensory characteristics of each sample during the positioning process.

Judges could move around the samples as many times as they wanted and take as much time as they deemed necessary to complete the task. Once a judge decided on the final configuration of the samples, three to five words from the provided list had to be provided. This verbalisation step was named ultra flash profiling (UFP) by Perrin et al. (2008).