[4-1330-C-02] Functional/Wellness Foods &Nutrition (1) Colour
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CIGR VI 2019 Oral Session | Food Function/Nutrition [4-1330-C] Functional/Wellness Foods &Nutrition (1) Wed. Sep 4, 2019 1:30 PM - 2:30 PM Room C (3rd room) [4-1330-C-02] Colour and Chemical Composition of Karasumi-like Chinook salmon (O. tshawytscha) Roe Relevant to its Quality *Senni Bunga1,3, John Birch1, Alan Carne2, Alaa El-Din A Bekhit1 (1. Departement of Food Science, University of Otago, New Zealand(New Zealand), 2. Department of Biochemistry, University of Otago, New Zealand(New Zealand), 3. Indonesia Endowment for Education (LPDP), Indonesia(Indonesia)) Keywords: Salmon roe, fermentation, colour, chemical composition Salt drying of fish products has been used as a food preservation method since ancient times for the production of shelf-stable products. Chinook salmon (O. tshawytscha) fish roe was used to produce a salted- dried (Karasumi-like) roe product. The changes in colour properties and chemical compositions (proximate, pH, water activity, salt content, and acidity value) were studied over 20 days of salt-drying at 4°C. Results showed that redness (a*) and yellowness (b*) were decreased gradually in value from 15.76 (at day 0) to 23.88 (at day 20) and from 24.88 (at day 0) to 3.44 (at day 20), respectively. Protein, lipid, ash, carbohydrate, salt content, and acidity value were higher (P <0.05) after salted-drying. The water activity decreased from 0.98 (at day 0) to 0.82 (at day 20). The pH value fluctuated but was overall lower at the end of the processing step. This study highlighted the potential for converting raw or frozen salmon roe into a salted-dried product with added value, that may have beneficial effects on the nutritional and functional characteristics of the processed product. ©International Joint Conference on JSAM and SASJ, and CIGR VI Technical Symposium joining FWFNWG and FSWG Workshops 2019 International Joint Conference (Sapporo, JAPAN) Colour and chemical composition of karasumi-like Chinook salmon (O. tshawytscha) Roe Relevant to its Quality Senni Bunga1,3*, John Birch1, Alan Carne2, Alaa El-Din A. Bekhit 1*, 1Department of Food Science, University of Otago, Dunedin, New Zealand 2Department of Biochemistry. University of Otago, Dunedin, New Zealand 3Indonesia Endowment for Education (LPDP), Indonesia *[email protected]; [email protected] ABSTRACT Salt drying of fish products has been used as a food preservation method since ancient times for the production of shelf-stable products. Chinook salmon (O. tshawytscha) fish roe was used to produce a salted- dried (Karasumi-like) roe product. The changes in colour properties and chemical compositions (proximate, pH, water activity, salt content, and acidity value) were studied over 20 days of salt-drying at 4°C. Results showed that redness (a*) and yellowness (b*) were decreased gradually in value from 24.49 (at day 0) to 5.18 (at day 20) and from 24.88 (at day 0) to 3.44 (at day 20), respectively. Protein, lipid, ash, carbohydrate, salt content, and acidity value were higher (P < 0.05) after salted-drying. The water activity decreased from 0.98 (at day 0) to 0.82 (at day 20). The pH value fluctuated, but was overall lower at the end of the processing step. This study highlighted the potential for converting raw or frozen salmon roe into a salted- dried product with added value that may have beneficial effects on the nutritional and functional characteristics of the processed product. Key words: Salmon roe, fermentation, colour, chemical composition. CIGR VI 2019 1. INTRODUCTION Fish roe refers to the eggs of fish is widely consumed throughout the world as delicacy food. Chinook salmon (also known as king salmon) is the most important fish species farmed commercially in New Zealand. According to the New Zealand Aquaculture Industry (2018) reported harvests of approximately 8,000 metric tonnes of salmon and contributed more than 50% of the world’s total king salmon supply. Large scale of the production leads to the utilization of the seafood by-product such as fish viscera, skin, head, and dark meat into new products such as food, nutraceuticals, pharmaceuticals and biotechnological applications (Kim & Mendis, 2006). The mature roe of Chinook salmon accounts for approximately 200 – 400 g of the total body weight and is considered a low-value by-product of the seafood industry. Fish roe is rich in proteins, vitamins, minerals and ɷ-3 polyunsaturated fatty acids, but the content of these nutrients vary amongst fish species (Bledsoe et al., 2003). Information on the nutrition values of fresh or frozen fish roe has been reported widely in previous studies (Al-Sayed Mahmoud et al., 2008; Bah et al., 2016; Bekhit et al., 2009b; Heu et al., 2006; Intarasirisawat et al., 2011; Mol & Turan, 2008), however, little information about changes in their composition upon processing. Processing may play an important role to improve the nutritional values of fish roe or it may degrade some components that might be beneficial for human health. Fish roe products are available in different forms. Salted, salted-dried, and salted- fermented roe are some of the roe products that are consumed in certain countries. In Asian countries, such as in Japan, South Korea and Taiwan, fish roe from salmon, pollock, flying fish, and herring are salted and known as Ikura, Tarako, Tobiko, and Kazunuko, respectively. Mullet fish species have also been the main roe used in a salted-dried product, which is known in Japan as Karasumi; Avgotaraho in Greece; Bottargo in Italy and Batarekh in Egypt. Salted-fermented fish roe is known as Karashi-mentaiko in Japan and Jeotgal in Korea. In this study, Chinook salmon roes were used to produce a salted-dried roe product similar to Karasumi. Changes in colour and physicochemical properties (roe skein size, proximate composition, pH, acidity, salt content, water activity, and weight loss) during the salted-drying process are important, as these factors will influence the quality and consumer’s perceptions of the fish roe. 2. Material and Methods 2.1. Fish roe sample and processing Fresh grade 1 Chinook salmon (O. tshawytscha) roe was used in this current study. The weight, length, and width of the roes were measured before processing. The surface of the roe skein then was covered with sea salt (7% of the wet weight). The drying process was conducted at 4°C in a chiller room for 20 days at fixed relative humidity of 80%. For optimal air circulation, stainless steel wire racks were CIGR VI 2019 used for the drying of the roe samples. Sampling of the roe was carried out every 4 days. Each sampling day, three whole fish roes were randomly chosen for further analysis. Schematic overview of the roe processing is shown in Figure 1. Raw salmon roe - Physical analysis - Chemical analysis Roe skein measurement (Weight, length, and width) Colour measurement Salting process Sampling every 4 (7% of the wet weight) days interval Process of fermentation - Salt drying; incubated over 20 days at 4oC Figure 1. Diagram process of salted-dried product from raw roe salmon 2.2. Measurement of roe colour The surface colour of the roes was measured using a Hunterlab MiniScan XE Plus Model 45/0-L (Hunter Associates Laboratory, Inc., Reston, VA, USA). The colour parameters L*, a*, b*, representing lightness, redness/greenness, and yellowness/ blueness, respectively, were measured at each sampling time. The instrument was calibrated using a standard black glass and a white tile according to the manufacture CIGR VI 2019 guidelines. The sample was placed on the tray and covered with a polyvinyl film (AEP FilmPac, Ltd, New Zealand). Three replicate readings from random positions were taken from each skein and the average value was used for statistical analysis. Chroma and hue angle were calculated based on the following formula: C= [a*2 + b*2]1/2 and HA=tan-1 b*/a*, respectively. 2.3. Chemical analysis 2.3.1. Weight loss Weight loss was measured every 4 days over the 20 days of salt-drying by removing the individual roe from the chiller room and were weighed using a Sartorius Type Universal U 4600 P scale. 2.3.2. Proximate compositions Moisture content was determined using a gravimetric measurement of water content by freeze-drying of 5 g of roe sample until a constant weight was achieved. Total lipid was extracted from 3 g of freeze- dried roe using Soxhlet extraction according to the official method (AOAC, 1995). Crude protein content was determined by Kjeldahl-Nitrogen method (% N*6.25) according to the AOAC Official method 981.10 using a Tecator Kjeltec Auto Sampler System 1035 apparatus. Ash content was determined on 2 g of freeze- dried samples, carried out in duplicates from three separated skeins. Carbohydrate content was calculated by subtracting the sum of lipid, protein, ash and moisture content from the total weight of samples. Energy value was determined using the following formula as described by Falch et al. (2010): [Energy (kcal/100g) = (lipid * 9) + (protein * 4) + ((carbohydrate * 4)] 2.3.3. pH and total acidity The pH value was measured using a pH meter (HANNA Instrument model PH209, USA) in a 10 g of sample homogenized with 100 mL of deionized water at 6000 rpm using a homogenizer (IKA® T25 Digital Ultra Turrax, TLS, Total Lab-System, Ltd) and the mixture was filtered. For titratable acidity, using the same homogenates, 1 ml of the roe filtrate mixed with 99 ml of deionized water then was determined by titrating against 0.1N standard sodium hydroxide (NaOH) solution. Complete titration was achieved when the colour turned to pink against three drops of phenolphthalein indicator. The % (v/v) acid in the sample was calculated as lactic acid using the following formula: 0.009 0.1 100 = ( ) 2.3.4.