Tilapia sensory analysis

2007b). Compared with the result above, 10% KHPL has similar effect on n-3/n-6 ratio as linseed oil and weaker than fish oil. In another human-related experiment, linseed oil

decreased n-6/n-3 ration in plasma of carnivorous consumers down to a relative higher value, 3.8 (Weill et al., 2002).

4.4 Tilapia sensory analysis

The effect of KHPL on sensory analysis of tilapia is focused on in this experiment. The sensory panel could identify difference in smell and taste.

4.4.1 Effect of KHPL on sensory analysis

KHPL used in this experiment was rich in phospholipids. KHPL gave tilapia a special olfactory response compared to feed with plant resource. Phospholipids contain much more unsaturated fatty acids than triglyceride. In cooking process, high level of unsaturated fatty acids presents a desirable smell by being oxidized and increases total amount of volatile compounds (Salter et al., 1988). The phospholipids in tilapia is believed put forth a quenching effect on the sum of heterocyclic Maillard compounds during food preparing (Whitfield et al., 1988). Olfactory difference is the result of diverse lipid composition and polar extent, also lipid interaction in the Maillard reaction plays a vital role in flavor formulation (Whitfield et al., 1988). Deficiency of phospholipids affected aroma of roast beef greatly (Mottram and Edwards, 1983; Mottram, 1998). Also, a hypothesis that lipid optimized level of sulfur compounds which gave food sulfurous odors affirmed the role of phospholipids in cooked meat (Mottram, 1998).

In respect of taste modification, up to 1.5 mg/g long-chain polyunsaturated fatty acid worsened the salmon flavor with metal taste and bitterness according to Refsgaard et al.

(Refsgaard et al., 2000). Also, total phospholipids as well as fatty acid content among phospholipids were highly linked to flavor uniqueness of beef (Larick and Turner, 1990).

Igene and Pearson demonstrated that phospholipids donated much more than triglyceride did

24 on warmed-over flavor (Igene and Pearson, 1979). In current research, content of long-chain polyunsaturated fatty acid in phospholipids is up to 0.01mg/g fillet, so the adverse effect could be neglected.

4.4.2 Effect of gender on sensory analysis

In aspect of smell, female has a gift of detecting odor, compared to male. This may be attributed to hormones, memory to smells and other causes. The gonad hormones are one of the reasons that lead to difference between odors detective ability of genders. They works directly on relevant organs or affect stimulations of central nerve system (Gandelman, 1983).

The rehydrolysateive hormones impact electronic connection between brain and olfactory cues (Simerly, 1990). For example, the excretion of estrogen increased performance of odor identification during ovulation and pregnancy (Good et al., 1976; Caruso et al., 2004). Date back to 1899, the perception of female to camphor solution was 0.001 ‰, higher than that of male to the same solution, 0.009‰ (Toulouse and Vaschide, 1899). In a later test, woman proved more sensitive than man on artificial chemical (Le. Magen, 1952). The perceptivity of women’s olfactory is 8 times accurate than that of men’s (Doty and Cameron, 2009). . Females also have advantage of naming and remembering odors. According to Lehrner, women performed outweighed men on smell identification test which had up-to-21-day retention interval (Lehrner, 1993). Women has better performance on smell verbal

processing, i.e. memory for naming memorable odor and classification. However, man and woman perform equally on primarily sensory acuity (Öberg et al., 2002). But in some studies, sexual variation was found in childhood when gonad hormones were not secreted in high level (Koelega and Köster, 1974). In addition, Larsson et al. claimed that based on result of an experiment in Sweden, gender has nothing to deal with odor detection nor identification (Larsson et al., 2000). In current sensory analysis, the gender ratio was balanced. In female group, no one was pregnant, so odor identification ability was not affected by estrogen.

25 4.4.3 Effect of ethnicity on sensory analysis

More than an identification of one’s birth, the word “ethnicity” presents a group of people having the same ancestry. Apart from anthropology, ethnicity includes the culture they were raised up and lifestyle they had, to be specific, food they got used to eat. In the current sensory analysis, ethnicity plays a role of great vitality in smell/taste distinguish. The sensory panelists were divided into 2 groups: Caucasian and Chinese.

Chinese have a 3000-year history of freshwater aquaculture since Yin dynasty. Freshwater fish, such as common carp, silver carp and so on, has become an unchangeable part in Chinese diet, so Chinese can bear high level of the smell/taste of mud and other smell/taste of which most were generated from on living environment of freshwater fish or the diet they have. In Chinese sensory panelists, 6 of them were from south coastal area of China, by whom the mean level of fishy taste/smell tolerance was increased. The reason was that marine fish take a higher portion on diet of Chinese living in the coastal area, compared to inland Chinese. A prove is the usage of marine algae: due to the availability and price, coastal dwellers consume higher portion of algae as vegetable or its substitution than inland dwellers (Bangmei and Abbott, 1987). However, fishy taste/smell endurance of Chinese was still lower than that of Caucasian. In contrast to Chinese, Caucasians are familiar with oil-rich marine fish, so they are not sensitive to fishy smell/taste. But due to unpopularity of freshwater fish in Europe, Caucasians have a strong response to freshwater fish, mainly on muddy smell/taste. It was the first time that 10 Caucasian judges eat Tilapia, so they would experience and classify odors from samples into olfactory memory that they have had.

In general, judgments of consumers to food and the originality of consumers are connected (Guerrero et al., 2009). It was believed that odor judgment associated with mother’s diet started can begin at even in pregnancy period (Hudson and Distel, 1999). Like language learning, odor/taste adaption depends on environments and ethnicity strongly: people will accept food with odors/tastes they are familiar and attempt to conclude all odors into their sensory memory. In Italy, children has developed a habit of drinking hot coffee which has become a part of their family and social life (Rozin and Cines, 1982). Children intake of

26 vegetable and fruit was also in the same habit formation: amount of vegetable and fruit parents ate, traditional family mealtime and intake-start age matters in a positive correlation (Cooke et al., 2003). A consumer-acceptance research showed that ethnicity had a great influence on snack choice of Americans and Asians: significant difference on fish snack choice while no difference on peanut snack. Asian consumers had a higher evaluations on fish snack than Americans did, due to the fish-eating habit of Asian (Suknark et al., 1998).

Familiarity is one of key roles in taste acceptance and can explain the alterations in cross-cultural food evaluation (Chung et al., 2012).