Consumption and physico‐chemical characteristics of smoked and smoked‐dried fish commonly produced in South Benin and contribution to recommended nutrient intakes

Abstract The work aims to assess the consumption and the physico‐chemical characteristics of smoked fish and smoked‐dried fish commonly produced and consumed in the South Benin. The consumption data were obtained from a survey involving 250 consumers, conducted in selected production localities of the Southern part of Benin, where 36 samples of smoked fish and smoked‐dried fish were collected. The highest protein contents (dry matter) were recorded in Cypselurus cyanopterus (85.1 ± 2.3%) and Sphyraena barracuda (84.5 ± 4.2%), while the highest lipid contents were recorded in Scomber scombrus (39.0 ± 9.2%) and Ethmalosa fimbriata (22.1 ± 6.3%). Smoked and smoked‐dried fish produced in South Benin contained 0.1%–12.5% (of total fatty acids) eicosapentaenoic acid and 0.1%–33.2% docosahexaenoic acid, which are the most abundant omega 3 polyunsaturated acids in these fish products. The median consumption of smoked fish (60.2 g/day) and smoked‐dried fish (18.2 g/day) contributed for 112% (281.1 mg) and 72% (180.4 mg), respectively, to the adult daily recommended intake of sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (250 mg/day). The daily protein intake related to the consumption of smoked fish and smoked‐dried fish corresponded to 36% and 24%, respectively, of the recommended intake suggested by European Food Safety Authority (0.8 g/kg.bw/day).

DP/MAEP, 2014). Among fish preservation methods, smoking is one of the most used (Alhassan, Boateng, & Ndaigo, 2012;Chabi et al., 2014;Kpodekon et al., 2014;Kumolu-Johnson, Aladetohun, & Ndimele, 2010;Yakubu & Ngueku, 2015). According to Berkel, Boogaard, and Heijnen (2005), smoking is carried out according to three methods which are cold smoking (30°C), hot smoking (65-100°C) resulting in cooked but not dried product, and smoke drying at 45-85°C resulting in hot smoking followed by drying. In Benin, traditional hot smoking and smoke drying are the smoking methods frequently performed by female processors and used to preserve fish . Smoked fish products are consumed all over the world as protein source (Alhassan et al., 2012;Desiere, Hung, Verbeke, & D'Haese, 2018;Kiczorowska, Samolinska, Grela, & Bik-Małodzinska, 2019). Smoked fish has good nutritional quality including protein, lipid, and fatty acids (Kiczorowska et al., 2019;Nunoo, Tornyeviadzi, Asamoah, & Addo, 2019;Tiwo, Tchoumbougnang, Nganou, Kumar, & Nayak, 2019). Adeyeye, Fayemi, and Adebayo-Oyetoro, (2018) and Amoussou et al. (2019) reported amino acids, vitamins, and oligoelements in raw and smoked fish. Fish products are also a good source of unsaturated fatty acids mainly the two essential fatty acids, namely alpha-linolenic acid and linoleic acid (omega 3 and omega 6) and semi-essential fatty acids, known as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Amoussou et al., 2019;Superior Health Council (SHC), 2016). Due to their nutritional quality, fish consumption results in important nutritional intake necessary for human health (Amoussou et al., 2019). Indeed, fish consumption is associated with reduction of death from coronary heart disease and reduction of colorectal cancer (Aglago et al., 2020;Clifton & Keogh, 2017). Although several studies were carried out on smoked fish and smoked-dried fish (Adeyeye, Oyewole, Obadina, & Omemu, 2015;Amos & Paulina, 2017;Anihouvi et al., 2019;Assogba et al., 2019;Olayemi, Raji, & Adedayo, 2012), to our best knowledge, none of them provided relevant information on the quality of some of their nutrients, mostly the fatty acids, and their contribution to nutrients intake in the Beninese context. This study aims to assess the consumption of smoked fish and smoked-dried fish produced in South Benin and to estimate the protein, lipid, and fatty acid daily intakes for adult in the study area.

| Study area, consumers, and data collection
Five municipalities of South Benin (Abomey-Calavi, Aguégués, Aplahoué, Comè, and Cotonou) recognized as main localities in which fishery activities were intensively carried out, were chosen to conduct this study. Fifty (50) adult (≥18 years old) consumers were randomly selected per municipality and interviewed when they came for buying fish in market or on processing sites, based on the assumption that fish buyers are potential fish consumers. The consumer survey was conducted as individual face to face interview using semistructured questionnaire administrated in French or Benin local languages (Goun, Fon, Mina, and Adja). The questionnaire was composed of two sections. The first section was composed of questions related to name, age, body weight, gender, sociocultural group, educational level, religion, household size, and marital status.
The second section was composed of questions related to the meal prepared out of smoked fish and smoked-dried fish, the methods of cooking fish as consumed, other grilled or smoked products consumed, frequency and quantity, number of people who will eat the purchased fish, time of the day when smoked fish and smoked-dried fish were consumed (breakfast, lunch, and dinner), places where smoked fish and smoked-dried fish were consumed.
About fifteen (15) markets and twenty-five fish smoking sites were visited during fifteen (15) days of survey. During this survey, the body weight of each interviewed consumer was taken using a balance (Seca LK N° 5,158). To calculate the quantity of smoked fish and smoked-dried fish consumed by each consumer, questions were asked about the cost of smoked fish or smoked-dried fish purchased and the number of people eating the quantity purchased. Similar quantity of smoked fish and smoked-dried fish at the same cost was then purchased and weighed using calibrated balance and this value was used to estimate the individual amount of daily consumed smoked fish or smoked-dried fish on the basis of the quantity consumed per meal and the consumption frequency recorded from the interviews. The daily consumption of smoked or smoked-dried fish was estimated by dividing the quantity of fish purchased for daily consumption by the number of people at the household level.

| Sampling and physico-chemical analysis
Thirty-six (36) samples of processed fish from three main fish species (Scomber scombrus, Merluccius polli, and Oreochromis niloticus) used to produce smoked fish and three main fish species (Cypselurus cyanopterus, Sphyraena barracuda, and Ethmalosa fimbriata) used to produce smoked-dried fish were randomly sampled. For each species, six samples (03 on smoking sites and 03 on markets) were collected in the municipalities where consumption survey was conducted.

| Daily intake estimation of macronutrients
One hundred and eighty-six (186) consumers eating smoked fish or/ and smoked-dried fish with a minimum frequency of once per month were selected among the 250 interviewed fish consumers for the estimation of the protein, lipid, and fatty acids daily intakes. The average content of each macronutrient (expressed in % of wet weight) recorded for smoked fish and smoked-dried fish was used to achieve this estimation. The calculated daily intake of protein (g/kg of body weight/day), lipid, and fatty acids (g/day) was then compared with a

| Statistical analysis
Descriptive statistics were performed on the collected survey data using Sphinx survey plus2 (version 4.5) software and Microsoft Excel (2013) for laboratory data. The proportions of smoked fish and smoked-dried fish consumers were compared using confidence intervals (CI) at 95%.
Kruskal-Wallis test was realized to show difference among the fish species composition, and significance was accepted at probability p < .05 using Statistica 7.1 (Statsoft France, 2006). Table 1 presents socio-demographic characteristics of the interviewed consumers of smoked fish and smoked-dried fish. The majority of the 250 surveyed consumers were aged ≤40 years (80.4%) and Christians (82.4 ± 4.7%). Most (74.4%) belonged to Goun, Adja, Fon, Pedah, and Mina sociocultural groups. They were from both genders with a higher proportion represented by women (61.2 ± 6.0%).

| Characteristics of consumers and factors associated with the consumption of smoked fish and smoked-dried fish
The higher proportion of female consumers is explained by the fact that in Benin, women are the ones in charge of purchasing food from TA B L E 1 Socio-demographic characteristics of the 250 surveyed consumers in the study area "akassa," "come," and "lio" (72.4%; 1.2% and 0.8% of consumers, respectively); cooked rice (53.6%); a cooked rice and bean product named "atassi," (2.4%); cooked wheat products (11.6%) and pounded yam (3.6%) (Data S1). Many cassava-based foods like "agbéli," "lafun," gari, and klaklou are also often consumed with smoked fish and smoked-dried fish (Data S1).
Smoked fish and smoked-dried fish are consumed daily by 21.6% of surveyed consumers. The respondents claimed to consume smoked fish or smoked-dried fish at home (100%), during lunchtime (89.2%) and during dinner (99.2%) ( Table 2).

| Physico-chemical characteristics of smoked fish and smoked-dried fish
The physico-chemical characteristics of the fish products are presented in Table 3. The moisture content recorded in the fish species studied varied between 18.9 ± 7.6% (E. fimbriata) and 67.2 ± 5.0% (M. polli) with the lowest moisture content recorded in the smokeddried fish species. The moisture content of S. scombrus is significantly higher (p < .05) than that of C. cyanopterus and E. fimbriata while the moisture content of M. polli is significantly higher than that of the three species of smoked-dried fish. The lower moisture content recorded in smoked-dried fishes when compared to the smoked fishes is due to the drying step which follows smoking process during smoked-dried fish production, leading to an important water loss from the products. Regarding the moisture content of E. fimbriata (18.9 ± 7.6%), similar value was reported by Ojimelukwe, Ekong, and Akachukwu (2017) in smoked E. fimbriata (18.7 ± 0.02%).
The pH values recorded on the fish products ranged between 6 and 7. The pH value recorded on M. polli was significantly higher (p < .05) than the values recorded on S. scombrus and C. cyanopterus.
Additionally, the pH value recorded on O. niloticus was also significantly higher (p < .05) than the value recorded on S. scombrus. This variability of pH between the fish products could depend on the species, but also on the postcapture preservation treatment. The pH value (6.4) recorded in smoked S. scombrus in this study is similar to the pH (6.1) reported by Kiczorowska et al. (2019) in the same specie smoked in Poland.
The average protein content of the six fish species is over 50% (dry matter) ( Table 3). The protein content of smoked S. scombrus (59.0 ± 9.2%) in this study is similar to the one (63.7 ± 4.7%) recorded in the same species by Aremu, Namo, Oko, Adelagun, and Yebpella The lipid content (% of dry matter) of the six fish species (Table 3) ranged between 11.0 ± 5.2% (for C. cyanopterus) and 39.0 ± 9.2% (for S. scombrus). The lipid content of S. scombrus was significantly higher (p < .05) than that of C. cyanopterus and S. barracuda. The lipid content of smoked E. fimbriata in this study (22.1%) is similar to the value reported by Ojimelukwe et al. (2017) in smoked E. fimbriata (20.2%).
The variability of the lipid content of the fish sample might be due to the fish species and the lipid loss during processing. Moreover, the use of vegetable oil by processors to make fish bright and attractive to buyers  might also influence the lipid content of these fishes. No significant difference was recorded in the lipid and protein contents inside fish species undergoing the same treatment (smoked or smoked-dried fish).

| Fatty acids composition of smoked fish and smoked-dried fish
The fatty acids composition varied widely among the 36 samples of smoked and smoked-dried fish (Data S3). According to species, palmitic acid (C16:0) and stearic acid (C18:0) are the predominant saturated fatty acids (SFA), ranging between 25.0% and 41.3%, and between 5.0% and 13.4% of total fatty acids, respectively (Data S3).
Specifically, the sum of the SFA in the smoked fishes (Table 4 and Data S3) ranged between 28.5% and 63.9% of the total fatty acids while the sum of the MUFA ranged between 17.8% and 43.4% of the total fatty acids and the sum of the PUFA between 4.2% and 53.6% of the total fatty acids. Regarding the smoked-dried fishes (Table 4 and Data S3), the sum of the SFA ranged between 39.0% and 70.8% of the total fatty acids while the sum of the MUFA ranged between 12.6% and 39.0% of the total fatty acids and the sum of the PUFA between 2.8% and 46.5% of the total fatty acids.

| Macronutrients intake from smoked fish and smoked-dried fish consumption
The consumption of smoked fish among the interviewed consumers ranged between 2.4 and 539.5 g/day/person with a median of 60.2 g/day/person. Regarding the smoked-dried fish, its consumption ranged between 0.5 and 592.1 g/day with a median of 18.2 g/ day. The protein, lipid, and fatty acids contents of individual samples of smoked fish and smoked-dried fish used to estimate the daily intake of these nutrients are presented as Data S4 and Data S5, respectively. The daily intake of protein, lipid, SFA, MUFA, PUFA, omega 6, omega 3 and sum of EPA and DHA through the consumption of both smoked fish and smoked-dried fish are summarized in Table 5.
The daily protein intake related to smoked fish ranged between 0.01 g/kg.bw/day and 3.1 g/kg.bw/day with a median of 0.3 g/ kg.bw/day while in the case of smoked-dried fish, it ranged between 0.005 g/kg.bw/day and 6.6 g/kg.bw/day with a median of 0.2 g/kg.bw/day. The third quartile (Percentile 75) of the daily protein intake (0.5 g/kg.bw/day) related to the consumption of both TA B L E 2 Moment and place of smoked fish and smoked-dried consumption fish (n = 250)

Percentage of consumers (%)
Frequency of consumption  The daily lipid intake ranged between 0.2 g/day and 51.7 g/day with a median of 5.8 g/day when considering the minimum and maximum daily consumption of smoked fish (2.4 g/day and 539.5 g/day).
In the case of the smoked-dried fish (0.5 g/day and 592.1 g/day), the daily lipid intake ranged between 0.1 and 72.0 g/day with a median of 2.2 g/day. The lipid requirement for adults should range between 55 and 83 g/day for men, and between 44 and 66 g/day for women, according to Superior Health Council (SHC), (2016).
The daily SFA intake through smoked fish consumption ranged between 0.1 g/day and 18.1 g/day while the daily SFA intake through smoked-dried fish consumption ranged between 0.03 g/day and 32.1 g/day. These ranges of daily SFA intake agreed with the recommended threshold of <22 g/day (for women) and <28 g/day (for men) (Superior Health Council (SHC), (2016)).
The daily MUFA intake related to the consumption of smoked fish ranged between 0.1 g/day and 12.4 g/day while it ranged between 0.01 g/day and 14.8 g/day when consuming smoked-dried fish. The daily MUFA intake for the maximum consumption of smoked fish (539.5 g/day) and the maximum consumption of smoked-dried fish (592.1 g/day) contributed to about 50% of adult recommended intake of MUFA, which ranges between 28 and 55 g/day (for men) and between 22 and 44 g/day (for women) (Superior Health Council (SHC), (2016)).
The daily PUFA intake through smoked fish consumption ranged between 0.02 g/day and 5.4 g/day while the daily PUFA intake through smoked-dried fish consumption ranged between 0.01 g/ day and 10.1 g/day. According to Superior Health Council (SHC), , adult PUFA recommended intake is 14-28 g/day for men and 11-22 g/day for women.
The daily omega-6 fatty acids intake through the consumption of smoked fish ranged between 0.01 g/day and 1.8 g/day while the daily omega-6 fatty acids intake through the consumption of smoked-dried fish ranged between 0.002 g/day and 2.8 g/day. The highest omega-6 fatty acids intakes through the consumption of smoked or smokeddried fish contribute to about 20% of adult recommended intake of omega-6 fatty acids which are 11-22 g/day for men and 8.8-18 g/day for women (Superior Health Council (SHC) (2016)).