Sensory quality of gonads from the green sea urchin, Strongylocentrotus droebachiensis, fed different diets.

ABSTRACT Dietary protein (<12% to 22%) and carbohydrate (9% to >25%) influences on the sensory characteristics of green sea urchin (Strongylocentrotus droebachiensis) gonads were examined in two feeding experiments, both lasting for 60 days. Gonad indices and sensory quality were evaluated, and were compared with those of gonads from wild sea urchins. Gonad growth was not significantly affected by dietary protein:carbohydrate ratio. Bitter taste was significantly affected by diet in both experiments, sweet taste was significantly affected by diet in only one experiment, whereas the taste attributes old/stale, metal/sour and aftertaste were not significantly affected by diet in either experiment. There was increased intensity of bitter taste with increased dietary protein, and the diet with the lowest protein concentration produced gonads not significantly different in taste from those of wild sea urchins. All sensory attributes related to texture (granularity, firmness, and melting) were affected by diet. Gonads from urchins given the diet with the lowest protein content did not differ significantly from those of wild sea urchins, but there was no consistent relationship between dietary protein and texture attributes.

KEY WORDS: gonad, protein, carbohydrate, formulated feed, diet, sensory quality, sea urchin, Strongylocentrotus droebachiensis

INTRODUCTION

Sea urchins are fished for their roe (gonads), but increasing demand over the past decade has resulted in over-fishing of natural populations (Keesing & Hall 1998, Andrew et al. 2002). This has led to a focus on sea urchin culture as a means to supply the roe market, and several cultivation approaches have been adopted. These include seeding natural habitats with farmed juveniles (Gomez et al. 1995), artificial rearing and feeding of adult urchins harvested from the wild (Fernandez & Caltagirone 1994, Kelly et al., 1998) and land-based, closed-system echiniculture (Le Gall, 1990, Grosjean et al. 1998). The last two approaches require feeds and feeding regimes that give yields of high quality roe at an acceptable cost (Caltagirone et al. 1992, Fernandez 1996, Lawrence et al. 2001). Several formulated feeds have been developed, and effects on roe production (de Jong-Westman et al. 1995, McBride et al. 1997, Pearce et al. 2002a, 2002b) and somatic growth (Cook et al. 1998, Klinger et al. 1998, Spirlet et al. 2001) have been examined. For a number of species, roe production is greater in urchins fed formulated feeds than in those given natural food sources, such as algae (Lawrence et al. 2001).

Less effort has been directed towards the study of how feeds influence other gonad characteristics, but recent studies have demonstrated that roe color (Goebel & Barker 1998, Watts et al. 1998, McLaughlin & Kelly 2001, Robinson et al. 2002), texture and taste (Pearce et al. 2003), may be manipulated via dietary means. Because the marketability and price of sea urchin roe is influenced by color, texture, and taste, gonad quality is at least as important as yield in the commercial roe industry (Pearce et al. 2002a, 2002b). With the aim of developing formulated feeds containing biochemical components that produce high quality roe, the present study was carried out to examine the effects of dietary protein and carbohydrate content on the sensory quality of the roe.

MATERIALS AND METHODS

Origin of Sea Urchins and General Experimental Conditions

Green sea urchins, Strongylocentrotus droebachiensis (test diameter 50-60 mm, wet weight 50-80 g), collected by scubadiving in Kvalsundet (69[degrees]52'N, 18[degrees]51'E), were brought to Tromso Aquaculture Research Station, northern Norway (69[degrees]50'N, 18[degrees]55'E). The sampling area was a barren ground, densely populated with sea urchins considered to have gonads of low quality. Prior to the start of experiments, the sea urchins were held for two weeks in 4001 fiberglass tanks supplied with running flow through seawater. The urchins were fed fresh kelp (Laminaria hyperborea) during the holding period. The wild sea urchins used for sensory analyses were collected outside Sommaroy (69[degrees]38'N, 17[degrees]56'E), in an area where urchins are harvested for export to Japan. These urchins are considered to have gonads of good quality.

The experiments were carried out in 755 1 plastic tanks (length: 1550, width: 1080, height: 690 ram) divided into eight chambers by vertical fiberglass lamellae that prevented urchins from moving from one chamber to another (Fig. 1). The tanks were fitted with a perforated false bottom and drain underneath to facilitate rapid removal of feces and waste feed debris. The tanks were drained and cleaned once a week. The tanks were supplied with 40 1 rain l flow through filtered ambient seawater (-34) through a sprinkler pipe (Fig. 1), and urchins were exposed to simulated natural photoperiod corresponding to Tromso latitude (~70[degrees] N). Maximum light intensity at the water surface was ca 150 lux. Temperature, recorded in the inflow water (EBI-125A temperature logger, Ebro electronics, Ingolstadt, Germany), decreased during both experiments (Expt I max: 7.2[degrees]C, min: 6.2[degrees]C, mean ([+ or -]SD) 6.8 [+ or -] 0.6[degrees]C. Expt II max: 6.2[degrees]C, min: Y5[degrees]C, mean ([+ or -]SD) 5.0 [+ or -] 0.7[degrees]C).

Diets and Diet Preparation

Two formulated wet feeds were prepared (Table 1). The first was the NIFAR (Norwegian Institute of Fisheries and Aquaculture Research) feed described previously (Raa 1998, Mortensen et al. 2004). The NIFAR Feed will hereafter abbreviated to N. N has ca. 59% protein and 24% carbohydrate (% dry weight). The second feed, NIFAR HighCarb (hereafter abbreviated to NHC) was formulated to contain a higher proportion of kelp meal than N, and NHC contained ca. 23% protein and 46% carbohydrate (% dry weight). In both feeds gelatine strengthened by the enzyme transglutaminase, was used as a binder.

[FIGURE 1 OMITTED]

Experimental Protocols

Two experiments, both lasting 60 days, were carried out. Expt I was run from October 13 to December 11, 2001 and Expt II from December 12, 2001 to February 6, 2002. In Expt I two feeds (N and NHC) were used. Each treatment was conducted in four replicate tank chambers with 50 urchins in each treatment chamber (Table 2). In Expt II, four feeding treatments were used: N and NHC as in Expt I, feeding N for 30 d then NHC for 30 d, and feeding NHC for 30 d followed by kelp for 30 d (Table 2). As in Expt I, there were four replicate chambers, each with 50 urchins, for every treatment.

Once a week the urchins were provided with 10 g feed [ind.sup.-1] [week.sup.-1] (ca. 2.6% body weight [d.sup.-1]). Residual feed was removed before new feed was added. Dead urchins were recorded and removed each day; dead animals were not replaced.

Initial samples of urchins (34 in Expt I and 25 in Expt II) were taken for analysis. Urchins were measured (test diameter and wet weight), then the tests were cracked open, gonads scooped out using a uni-spoon and then blotted dry on a paper towel. Gonad weight ([+ or -]0.1g) was measured and gonad color was assessed (only in Expt. I). Color assessment was done by the CIE 1976 (L*a*b) method using a Minolta Chroma Meter CR-200 (Minolta Camera Co., Osaka, Japan). Gonad index was calculated as follows:

Gonad index

= [wet gonad weight (g)/whole urchin weight (g)] x 100 (1)

At the end of the experiments, weight and gonad weight of all individuals were measured as described above, and color was assessed (only in Expt I). Gonad samples were taken for sensory analyses. The gonad of a single individual provided insufficient material for both sensory analyses, so analyses were carried out using gonads pooled from 3-5 individuals from each treatment.

Sensory Analyses

Prior to sensory evaluation of urchin roe, the procedures were as follows: Urchins were starved for 1 wk to allow gut evacuation, and were then stored dry at 4[degrees]C for 12 h. The test was cracked open, gonads scooped out and the gonads were placed in a container with brine (3.1% NaCl) for 5 min. Gonads were then transferred to a second container of brine (2.8% NaCl) for 30 rain, and then to a container with alum (2.5% NaCl/2.5% alum) for 30 rain. The gonads were then removed and dried on paper towel for 1 h and then transferred to wooden trays. The processing procedure was similar to that used commercially in Norway. The gonads were stored overnight at 4[degrees]C in covered, coded plastic beakers before being used for sensory assessment.

Sensory analyses were performed by six (Expt I) or nine (Expt II) trained panelists, using a descriptive test and conventional profiling in two replicates. During training, panel members agreed upon a profile of 10 attributes: total smell, granularity, firmness, melting of roe, sweet taste, bitter taste, fresh taste, old/stale taste, metallic/sour taste and aftertaste (Table 3). A continuous line scale from low (0) to high (10) intensity was used. The roe samples were served to each panelist in a randomized order. The assessments were performed in a laboratory specifically designed and equipped for sensory analysis (ISO 8589), and data were registered electronically using a Senstec system (Tecator AB, Hoganas, Sweden).

Data Analysis

The effects of diet on gonad growth and gonad color (Expt I) were analyzed using Kruskal-Wallis and Mann-Whitney tests. The sensory data were analyzed by an ANOVA followed by Tukey multiple comparisons test. In all analyses, significance was assumed when P < 0.05. Statistical tests were carried out using the Statistical Analysis System SAS, windows version 6.12, and StatView-98 (SAS Institute Inc, Cary NC, USA).

RESULTS

Gonad Yield

There was a significant increase in gonad index during the experimental period in both experiments (Fig. 2). Gonad index increased from 6.4% (median) at the beginning of Expt I to 12.8% (median) at the end, and in Expt II the gonad index increased from 6.3% (median) at the start to 15.0% (median) by the end. There were no significant differences in gonad index among feed treatments in either experiment (Fig. 2).

Gonad Color

There were no significant changes in either brightness (L*), redness (a*) or yellowness (b*) during Expt I, and no significant effect of diet on gonad color was observed (Fig. 3). Color measurements were not repeated in Expt II.

Sensory Analysis

In Expt I the sensory analysis revealed significant differences in 6 out of 10 sensory attributes. These were granularity, firmness, melting, sweet taste, bitter taste, and fresh taste (Table 4). Gonads from wild sea urchins had higher intensity in all these attributes except bitter taste and melting. This means that the sensory panel evaluated the gonads from wild sea urchins to have a higher degree of granularity, it was firmer, sweeter and fresher compared with gonads from sea urchins fed experimental diets. The gonads from wild sea urchins were evaluated as less bitter and less melting than gonads from counterparts fed experimental diets. In addition to the sensory score, the panel was asked to give qualitative comments to the sensory attribute aftertaste. The wild sea urchins were described as "predominately sweet and fresh," with an "association to carrot and cucumber,'" and "touch of bitterness." Sea urchins fed experimental diet had an aftertaste described as "predominately bitter" somewhat "sour and metallic." There was no significant difference between the experimental diets in any sensory attribute.

In Experiment II the sensory panel revealed significant differences in 5 out of 10 sensory attributes. These were total smell, granularity, firmness, melting and bitter taste (Table 5). The panelists were unable to discriminate between gonads from wild sea urchins and gonads from sea urchins fed the diet with the lowest protein content, the NHC-Kelp, which was not significantly different from wild in any sensory attribute. For the sensory attribute bitter taste, the diet with the second lowest protein content, NHC, was not significantly different from wild, whereas the sensory panel evaluated the diets with higher protein:carbohydrate ratios (N and N-NHC) as significantly more bitter that wild. For the remaining four sensory attributes, no clear relationship between protein:carbohydrate ratio in the diet and sensory score was evident (Table 5).

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

DISCUSSION

Gonad growth

Gonad index increased from about 6% to above 12 and 15% in Expt I and II respectively. In the present study, no comparisons were made to sea urchins fed kelp or other natural diets. However, several previous experiments have shown that gonad growth of Strongylocentrotus droebachiensis fed the NIFAR feed significantly exceeds that of S. droebachiensis fed kelp (Laminaria hyperborea) (Raa 1998, Siikavuopio et al. 1999, Mortensen et al. 2004). This in accordance with an ever growing body of literature showing that, for a number of sea urchin species, gonad production with formulated feed is greater than with natural food sources, such as algae (Loxeschinus albus e.g., Lawrence et al. 1997, Olave et al. 2001, Paracentrotus lividus e.g., Fernandez & Pergent 1998, Spirlet et al. 2000, S. droebachiensis de Jong-Westman et al. 1995, Klinger et al. 1998, Walker & Lesser 1998, Pearce et al. 2002b, Pearce et al. 2003).

The diets used in the present experiments differed in protein and carbohydrate content. However. the differences in protein:carbohydrate ratio did not influence the gonad growth significantly. The two formulated feeds, N and NHC had a protein content of 59 and 23% respectively. The diet N-NHC is assumed to have had a protein content between that of N and NHC. The protein content of the last experimental diet, NHC-Kelp, is uncertain because no measurements of the proximate composition of Laminaria hyperborea were carried out. The protein content of kelp varies through season and between habitats, but is estimated to be within the range of 5% to 15% of dry weight in Laminaria sp. from Northern Norway (Haug & Jensen 1954) Thus the protein content of the NHC-Kelp diet was probably significantly below 23%. de Jong-Westman et al. (1995) reported significantly higher gonad yields in S. droebachiensis fed prepared diets containing 20% protein compared with similar diets containing only 10% protein. According to, Pearce et al. (2003), no significant difference in gonad yield was observed in S. droebachiensis fed prepared diets with 19 %, 24 %, and 29% protein. The authors concluded that gonad enhancement is most likely maximized a dietary protein content in the range of 10% to 19%, whereas little is gained by a further increase protein content (Pearce et al., 2003). Parallel results are obtained for other species. Akiyama et al. (2001) fed young Paracentrotus depressus prepared diets containing 10%, 20%, 30%, 40%, and 50% protein. There appeared to be a trend of increased gonad index (although not statistically significant) with increasing diet protein content up to 30%, followed by a decrease in gonad index with a further increase in dietary protein content (40% and 50% protein) (Akiyama et al. 2001). Our results suggest that with the presented feed formulations, protein levels may be reduced to at least 23% percent without any reduction in gonad yield in adult S. droebachiensis.

Gonad Color

There was no effect of diet (protein:carbohydrate ratio) on gonad color in Expt I, and the color of gonads from sea urchins fed experimental diets did not differ from the start sample of wild sea urchins. In the study of Pearce et al. (2002b) gonad color was affected by protein concentration, where diets containing 19 and 24% protein produced better gonad color than a 29% protein diet. They found, however, no significant difference between the two lowest protein concentrations. However, caution should be taken comparing results obtained with different feed formulations, as both pigment source (Robinson et al., 2002) and binder type (Pearce et al., 2002a) used in the feed are shown to affect gonad color. Furthermore, McBride et al. (2004) showed that even when the same feed is used, seasonal differences in gonad color occur. The authors suggested that the ability for uptake of carotenoids is affected by the reproductive stage of the gonads.

Gonad Taste

The sensory attribute bitter taste was affected by diet in both experiments, whereas the relationship between diets and both sweet taste and fresh taste was less clear (only significantly affected by diet in Expt I). The sensory attributes old/stale taste, metal/sour taste and aftertaste were not significantly affected by diet in either experiment, and gonads from sea urchins fed experimental diets could not be discriminated from wild sea urchins on these attributes. The gonads of S.droebachiensis (both wild individuals and individuals fed artificial diets) had a low intensity of old/stale taste and metal/sour taste, whereas aftertaste was evaluated as medium strong.

Previous studies have shown a relationship between protein content in the diet and bitter taste of the gonad (Hoshikawa et al. 1998, Pearce et al. 2003), and a possible relationship to specific free amino acids (FAAs) was suggested (Pearce et al. 2003). The characteristic taste of many kinds of seafood is elicited by FAAs (Kato et al. 1989, Fuke & Konosu, 1991, Fuke 1994). To our knowledge, the taste active FAAs in S.droebachiensis have not been identified. However, in other sea urchin species (S. nudus, S. pulcherrimus), omission tests on extracts have identified glutamic acid, glycine, alanine, valine, methionine, arginine, lysine, and serine as taste active amino acids. Glycine and alanine are known as sweet amino acids (Fuke & Konosu 1991), and when omitted, strong bitterness and deterioration of characteristic flavor occur. Valine (Fuke et al. 1989, Fuke & Konosu 1991), and a recently described amino acid, pulcherrimine (Murata et al. 2001), are known to produce bitter taste in sea urchins. Specific peptides are also known to produce bitter taste in seafood (Kato et al. 1989). We did an analysis of FAA content in frozen gonad samples from the present study, but the sample available was too small to carry out replicate measurements and the results are therefore not included. The data did, however, indicate a relationship between bitter taste and high concentrations of the bitter amino acid valine and/or low concentration of the sweet amino acid glycine.

Gonad Texture (Granularity, Firmness and Melting)

The sensory attributes connected to texture were affected by diet in both experiments. In Expt I, gonads from wild sea urchins were significantly different from that of sea urchins fed experimental diets. For the attributes granularity and firmness, gonads from NHC tended to have a score most similar to that of wild sea urchins, whereas the opposite was the case for melting. However, this tendency was not significant. In Expt II, we could not identify any clear relationship between the protein:carbohydrate ratio in the diet and sensory score on the attributes granularity, firmness and melting. The diet with the lowest protein:carbohydrate ratio, NHC-Kelp, was not significantly different from wild sea urchins. Interestingly, neither was the diet with the highest protein:carbohydrate ratio, N. Differences between the remaining diets did not follow any systematic pattern. Studies addressing the effect of diet on gonad texture are not unambiguous. Pearce et al. (2002b) found no significant difference in texture among wild sea urchins, kelp-fed sea urchins and sea urchins fed prepared diets. In a recent study, we observed differences in texture between wild sea urchins and laboratory reared sea urchins fed different formulated feeds (Dale et al. 2006). McBride et al. (2004) compared the texture of wild animals to that of laboratory reared animals fed two different prepared feeds and one algal diet. There were no differences in texture between the laboratory reared animals, but the texture in wild animals was significantly better than animals fed both the algal diet and the prepared feeds (McBride et al. 2004). According to Hammer et al. (2006), the protein content in the diet influenced the volume of nutritive phagocytes and gametes, where the high protein -low carbohydrate diet resulted in lower volume of the nutritive phagocytes and a promotion of gamete growth. Texture was not addressed in the study of Hammer et al. (2006), but the texture of gonads filled with gametes are generally soft and less appealing compared with the firmer texture of gonads filled with nutritive phagocytes (Unuma 2002). Thus, the study of Hammer et al. (2006) suggests that gonad texture is negatively affected by high levels of protein in the diet.

Studies addressing the effects of dietary protein on biochemical composition and reproductive status are not unambiguous (Hammer et al. 2006). The authors emphasized that the variation of dietary protein levels using practical ingredients, as done in most studies, results in a concomitant variation in other nutrients. Thus potential effects may be caused by the variation in other nutrients. These concerns are valid in the present study as well.

ACKNOWLEDGMENTS

This project was funded by the MABIT program. The authors thank Arnes Batsfjord Ltd for producing the formulated feed, Atle Mortensen, Malcolm Jobling, and one anonymous referee for providing valuable comments on earlier drafts of this manuscript.

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Walker, C. W. & M. P. Lesser. 1998. Manipulation of food and photoperiod promotes out-of-season gametogenesis in green sea urchin, Strongylocentrotus droebachiensis: implication for aquaculture. Mar. Biol. 132:663-676.

Watts, S. A., A. Boettger, J. B. McClintok & J. M. Lawrence. 1998. Gonad production in the sea urchin Lytechinus variegatus (Lamarck) fed prepared diets. J. Shellfish Res. 17:1591-1595.

STEN. I. SIIKAVUOPIO, (1) TRINE DALE (2) * AND MATS CARLEHOG (1)

(1) Norwegian Institute of Fisheries and Aquaculture Research, Tromso N-9291, Norway; (2) Norwegian Institute for Water Research, Oslo N-0349, Norway

* Corresponding author. E-mail: [e-mail]

TABLE 1.
List of ingredients (above the dotted line) expressed as a
percentage of wet weight, and the resulting proximate composition
of the formulated feeds (below the dotted line) presented as a
percentage of dry weight. * Determined by difference.

                                                    NIFAR
                                                   Highcarb
Ingredient/constituent               NIFAR Feed      Feed

Fish skin (Pollachius virens)
  (wet weight)                         89.05        81.77
Kelp meal (Luminaria hyperborea)        8.90        16.35
Starch (potato meal)                    1.78         1.64
Glucose                                 0.09         0.08
[beta]-carotene
  ([beta]-carotene 10% CWS. Roche)      0.02         0.02
Ascorbic acid                           0.02         0.02
Transglutaminase                        0.13         0.12
Moisture                                62.6         46.0
Ash                                     15.7         29.6
Protein                                 59.1         23.9
Lipid                                    0.5          0.4
Carbohydrate *                          24.6         46.1

TABLE 2.
Feeds and feeding regimes used in experiment I and II. N = NIFAR
feed, NHC = NIFAR Highcarb Feed and K = kelp (Laminaria hyperborea).
Wild sea urchins (W) were used as reference for sensory and biochemical
analyses.

                                    Experiment I

                                  Feeds and feeding
Treatment   No. of sea urchins         regimen         Days

    1              200                   N              60
    2              200                   NHC            60
    3
    4
Reference                                W               0

                                    Experiment II

                                  Feeds and feeding
Treatment   No. of sea urchins         regimen         Days

    1              200           N                     60
    2              200           NHC                   60
    3              200           N [right arrow] NHC   30:30
    4              200           NHC [right arrow] K   30:30
Reference          200           W                      0

TABLE 3.
Sensory panel guide, with list of sensory attributes and their
evaluation criteria. The sensory attributes were evaluated
on a scale from 0-10 points (from none to high intensity of the
given attribute).

Sensory Attribute   Evaluation Criteria

Total smell         Evaluate the intensity of all kinds of smell.
                      Qualitative comments given.
Granularity         Evaluate how well the "granules" can be discerned.
                      Scale: not possible to discern single "granules"
                      (slimy) to easily discerned "granules" (with
                      reference to capelin roe).
Firmness            Evaluate the robustness of the gonad when handled
                      with a spoon. Scale: very soft (slimy) to very
                      firm (elastic; the gonad segments return to
                      original shape after handling).
Melting             Evaluate the tendency of melting by pressing the
                      sample between tongue and palate before chewing.
                      Scale: not melting (the gonad sample keeps its
                      shape in the mouth) to melting (melts like butter
                      in the mouth).
Sweet taste         Evaluate the intensity of sweet taste.
Bitter taste        Evaluate the intensity of bitter taste.
Fresh taste         Evaluate the intensity of taste associated with
                      sea, seagrass and seashore.
Old/stale taste     Evaluate the intensity of taste perceived as old,
                      stale and nauseating.
Metal/sour taste    Evaluate the intensity of metallic/sour taste.
Aftertaste          Evaluate the intensity of aftertaste after the
                      sample has been spitted out. Qualitative
                      comments given.

TABLE 4.
Sensory comparison between gonads from wild
Strongylocentrotus droebachiensis and S. droebachiensis fed
two different experimental diets. N = NIFAR feed and
NHC = NIFAR High Carb Feed. Results are given as means
(n = 6). Means with similar letter suffix are not significantly
different at a 5% level. Symbols; *** = P < 0.001, ** = p < 0.01,
* = p < 0.05, and ns = not significant (P > 0.05).

                                                  Wild Sea
Sensory Attribute   Significance    N      NHC    Urchins

Total smell              ns        1.6a   2.2a      1.6a
Granularity              **        4.Ob   4.9ab     5.8a
Firmness                ***        3.8b   4.6b      5.6a
Melting                  **        5.8a   6.4a      4.76
Bitter taste            ***        5.9a   5.4a      3.Ob
Sweet taste              *         3.2b   2.9b      4.7a
Fresh taste              **        3.2b   3.8b      5.Oa
Old, stale taste         ns        1.4a   1.0a      0.9a
Metal; sour taste        ns        4.1a   3.6a      2.7a
Aftertaste               ns        4.9a   4.9a      4.9a

TABLE 5.
Sensory comparison between gonads from wild Strongylocentrotus
droebachiensis and S. droebachiensis fed four different
experimental diets. N = NIFAR feed, NHC = NIFAR High Carb Feed.
Results are given as means (n = 9). Means with similar letter
suffix are not significantly different at a 5% level. Symbols;
*** = P < 0.001, ** = p < 0.01, * = p < 0.05, and ns = not
significant (P > 0.05).

Sensory Attribute   Significance     N     N-NHC

Total smell              *         1.7b    2.2ab
Granularity             ***        5.0ab   3.5c
Firmness                 **        4.5ab   3.6b
Melting                 ***        6.0ab   6.7a
Bitter taste             *         4.4a    4.4a
Sweet taste              ns        3.5a    3.7a
Fresh taste              ns        4.0a    4.2a
Old/stale taste          ns        0.9a    0.9a
Metal/sour taste         ns        3.0a    2.9a
Aftertaste               ns        4.6a    4.4a

                                       Wild Sea
Sensory Attribute    NHC    NHC-Kelp   Urchins

Total smell         2.3ab    2.3ab      2.4a
Granularity         4.3be    5.1ab      5.7a
Firmness            4.2ab    5.0a       5.2a
Melting             6.3a     5.3b       5.2b
Bitter taste        3.7ab    3.6ab      3.2b
Sweet taste         3.8a     3.5a       4.1a
Fresh taste         4.4a     4.2a       3.9a
Old/stale taste     1.3a     1.0a       1.8a
Metal/sour taste    2.7a     2.6a       2.5a
Aftertaste          4.4a     4.4a       4.6a