Natural source of carotenoids for salmonids and shrimps

Dominique Corlay, Aquaculture Natural Solutions

Color intensity for salmon and shrimp represent major quality criteria affecting consumer preferences (Parisenti et al., 2011) and giving a significant added value to the products. Carotenoids such as astaxanthin are also key nutrients in various physiological functions such as reproduction and can help to sustain the animal health status. On the other side, demands from customers lean towards more natural and sustainable products, free of any synthetic additives. Natural carotenoids such as Panaferd-AX are available on the aquafeed market and provide efficient nutritional solutions for both farmed salmonids and shrimps.

Sources of carotenoids

In nature, wild salmon and shrimp get carotenoids from various primary producers such as microalgae, bacteria or yeast and then by live food. In aquaculture, dry feed is by far the only source. For shrimps, in some low-density production systems (<15 PL/m²) with good environmental conditions, farmed shrimp may find in the benthos sufficient quantities of carotenoids (Fig. 1). But in most intensive farming cases for shrimp, salmon and trout, the addition of carotenoids in the feed is fully needed.

Various feed additives containing carotenoids such as astaxanthin are available from two major origins.

Synthetic astaxanthin is chemically engineered through complex reactions from crude oil-based components. But this synthetic form only contains astaxanthin under various isomeric forms, not existing in nature. Considered as a “chemical dye” by some, it tends to be less used by premium farms in the salmon and trout industry and even ban by some food stores.

Natural carotenoids can be extracted from various organisms and have the advantage to contain various carotenoids such as astaxanthin, adonirubin, canthaxanthin and adonixanthin. These sources also have a nutritional value (protein content) when not synthetically formed. Three major sources of natural astaxanthin are available on the market: the microalgae Haematococcus pluviatilis, the yeast Phaffia rhodozyma and the bacterial micro-organism Paracoccus carotinifaciens, better known under the brand name Panaferd-AX®. Table 1 compares the main specifications between Panaferd-AX and synthetic astaxanthin.

Benefits for salmon: Color and health

Natural carotenoid source is well known and used by part of the salmon industry for many years. In a study conducted in Scotland (ENEOS Corporation data), the efficacy of Panaferd pigment at different standard pigment rates (40 and 70 ppm) in Atlantic salmon (Salmo salar) was compared to synthetic astaxanthin. A stability study was also performed to evaluate the carotenoid stability of salmon fillets under freezing

Credit: Kvarøy Artic, Norway

conditions (-25°C) for 6 months. Atlantic salmon smolts from the same genetic strain, were sourced from a Scottish hatchery and raised to market size. Pigmented diets contained the same astaxanthin level: 40 or 70 ppm (PF1 and PF2, respectively) and either from Panaferd-AX or synthetic form (SA1 and S2).

At the end of the trial (triplicates), no significant differences in growth, SGR and FCR were observed either during the growing period demonstrating there was no relationship between pigment source (synthetic versus Panaferd-AX) or carotenoid concentration.

Regarding the results on the flesh quality, all Panaferd groups performed very well and after 17 months reached a color level on the Roche SalmoFan® in accordance with the market expectations (Fig. 2).

The test stability results at freezing temperature (-25°C) confirm the excellent stability of carotenoids of Panaferd-AX salmon (Table 2) without any difference between natural and synthetic astaxanthin. In the smoking process, similar results were found by Lerfall et al. in 2016 and largely confirmed by the smoked Scottish salmons found in most food stores around the world. Significant quantities of other carotenoids such as adonirubin in the salmon flesh are very typical of Panaferd®-AX use, where synthetic-based pigment contains only one form of carotenoid. Recent studies have proven the strong anti-oxidative, anti-tumorpromoting and anti-carcinogenic activities of adonirubin (Maoka et al., 2013). Panaferd®-AX carotenoids such

Figure 1. Total carotenoid content in shrimp P. vannamei according to their farming density (low density at 15 PL/m²; high density at 400 PL/m²). Adapted from Quintana-Lopez et al., 2019.

Table 1. Comparative table between PANAFERD-AX and synthetic astaxanthin.

Origin Source

Product name/Brand name Production method Product form

Chemical form

Size of the organism Astaxanthin concentration Presence of other carotenoids Nutritional value

(as is)

Color enhancing efficiency and stability Market and certifications

Natural carotenoids

Bacterial micro-organism Paracoccus carofinifaciens

Panaferd-AX™

Fermentation Powder Free form Isomer 3S-3’S, same as wild salmon 0.2 µ 2% mini Adonirubin, canthaxanthin, adonixanthin …

Synthetic astaxanthin

Synthetic product Crude oil derived origin Various suppliers: DSM, BASF… Chemical reactions process Powder Free form Mixture of enantiomers: 3S,3S' 3R,3R 3S3R; not found in nature N/A 8 to 10% No other carotenoids

Crude protein: >50% Crude fat: 1.9% No value

Good bioavailability for all species. Good stability Good efficiency and stability

Authorized worldwide and Authorized worldwide

by all food retailers

Fully ban by the organic standards Authorized in the EU organic standards Not authorized by some food retailers

Table 2. Carotenoids in the salmon flesh (mg/kg) during the test stability at freezing temperature (-25°C).

At starting point (in mg/kg) PF1 PF2 SA1 SA2

Canthaxanthin (coefficient 0.92) 0,57 0,42 0,10 0,07 Adonirubin 1,54 1,23 0,00 0,04

Astaxanthin 3,30 2,96 3,97 3,92

Total carotenoids 5,63 4,77 4,26 4,31

After 6 month at -25°C

PF1 PF2 SA1 SA2

Canthaxanthin (coefficient 0.92) 0,53 0,35 0,07 0,06 Adonirubin 1,43 1,06 0,05 0,05

Astaxanthin 2,97 2,54 3,57 3,43

Total carotenoids 5,12 4,06 3,69 3,55

Figure 2. Roche Color score after 17 month growing period.

Figure 3. Redness a* value on head and body in shrimp. as astaxanthin are present as free and the same isomeric forms (3S3’S) as in wild salmon. In synthetic astaxanthin, astaxanthin is a mixture of enantiomers, not existing in nature. This difference can be used to distinguish between farmed and wild salmon through an approved method by the FDA (Turujman, 1997).

Benefits for shrimp: Color and health

Carotenoids can also be considered as essential nutrients for shrimp. Various studies have confirmed their implications in many physiological functions and health benefits such as survival, growth, reproduction, stress and disease resistance (Wade et al., 2015). In a study conducted at Songkhla University in Thailand (ENEOS data), juveniles (1.5 g) of P. vannamei were fed for 4 weeks with 3 diets: Control (no carotenoid addition), Panaferd-AX® at 0.5 kg and 1.25 kg/ton respectively. Color parameters such as redness (a* value) were obtained with a Hunterlab® ColorFlex on cooked shrimp (5 min boiling; Fig. 3). Shrimps fed with Panaferd-AX feature significant better red color compared to control.

During a farm-scale evaluation in Panama (8 ponds 1.75 ha each; 4 control and 4 with Panaferd; same PL origin and stocking density), in the Panaferd ponds, shrimps were fed with natural carotenoids at 2.5 kg/ton, during 30 days before the final harvest. A color evaluation was conducted after cooking, using the color chart commonly used in Latin America (chart A1 to A4). Figure 4 details the significant difference in color variation between the

Figure 4. Color evaluation of shrimp at harvest after 30 days feeding with Panaferd-AX at 2.5 kg/ton feed and control (no carotenoids).

Figure 5. Antioxidant enzyme activities of P. vannamei fed with Panaferd for 4 weeks.

two diets and confirm the significant effect of natural carotenoids on color.

The health benefits of carotenoids from Panaferd-AX® for shrimps have been also evaluated. After 30 days of feeding with the natural carotenoids, shrimps feature significant additional activities of the major antioxidant enzymes (SOD: SuperOxide Dismutase; and CAT: Catalase). Catalase is a major antioxidant enzyme, which is responsible for scavenging reactive oxygen species (ROS) and protecting tissue against damage. Shrimp fed with Panaferd-AX featured significantly higher CAT and SOD activities than the control (Fig. 5).

Conclusion

Natural pigment Panaferd®- AX confirms it represents a reliable and stable pigment for salmon and shrimp. Natural carotenoids also prove to be valuable nutriments enhancing the animal health status in intensive farming conditions. On the market side, consumer expectations for more food free of synthetic additives are now more prevalent around the world. As color is the symbol of salmon and shrimp, consumers expect clear statements on the pigment source.

More information: Dominique Corlay

Consultant Aquaculture Natural Solutions, France E: ansaqua.dc@gmail.com E: panaferd.sales@jxanci.com