Evaluation of growth rate and semi‐refined carrageenan properties of tissue‐cultured Kappaphycus alvarezii (Rhodophyta,Gigartinales)

This study aimed to evaluate and compare the quality of κ‐carrageenan obtained from tissue‐cultured and field‐cultured Kappaphycus alvarezii. Carrageenan properties including yield, viscosity, gel strength and sulfate content were studied. After 60 days of cultivation, tissue‐cultured K. alvarezii showed a higher growth rate (6.3 ± 0.01% day^?1) than field‐cultured seedlings (3.4 ± 0.3% day^?1). The obtained carrageenan yield from tissue‐cultured (67.3 ± 16.4%) was higher than field‐cultured K. alvarezii (51.5 ± 21.0%). Gel viscosity of carrageenans from tissue‐cultured K. alvarezii (1280.0 ± 25.0 cP) was found significantly higher than field‐cultured samples (87.8 ± 20.9 cP). The 1.5% gel solution of tissue‐cultured and field‐cultured K. alvarezii exhibited gel strengths of 703.5 ± 14.1 and 288.3 ± 19.3 g cm^?2, respectively. The average sulfate content of carrageenans was found to be significantly different between tissue‐cultured and field‐cultured K. alvarezii with 34.2 ± 10.9 and 7.5 ± 6.7%, respectively. Tissue culture is recommended to produce high quality seedlings by providing optimized culture conditions to the seaweed. This approach can serve as an alternative way to solve the seedling shortage problems currently faced by the seaweed industry.     

Effect of epiphyte infection on physical and chemical properties of carrageenan produced by Kappaphycus alvarezii Doty (Soliericeae,Gigartinales, Rhodophyta)

Epiphytism of filamentous red algae is a serious problem in Kappaphycus farms in the Philippines, Indonesia, Malaysia, and Tanzania. The causative organism of epiphyte outbreak has been identified as Neosiphonia apiculata (Hollenberg) Masuda and Kogame, but its actual effect on carrageenan quality has not yet been established. Therefore, yield and quality of carrageenan from healthy and infected specimens were examined. Infected specimens showed 20.5?±?2.5 % DW lower carrageenan yield compared with the healthy seaweed (65.5?±?4.2 % DW). Infected specimens also had a higher phenolic and fatty acid content, compared with healthy specimens. The carrageenan from the infected seaweed showed 74.5?±?2.8 % lower viscosity, 52.6?±?3.6 % lower gel strength, 22.9?±?1.5 % higher syneresis, and 5 °C higher melting temperature as compared with carrageenan from healthy specimens. FTIR and ¹³C-NMR analysis of carrageenan from infected seaweed did not show any differences in their functionality or carbon atom chemical shift as compared with healthy and standard k-carrageenan. However, size exclusion chromatography showed the infected carrageenan molecular size to be 80 kDa as compared with 800 kDa for the healthy and standard k-carrageenan. These findings prove that infection of Kappaphycus by the filamentous red algae epiphyte, N. apiculata, reduces carrageenan molecular size and affects the physical properties of the carrageenan.     

Effects of improved post-harvest handling on the chemical constituents and quality of carrageenan in red alga,Kappaphycus alvarezii Doty

Red alga Kappaphycus alvarezii Doty is an important commercial species widely cultivated in southeast Asian countries for its polysaccharide, kappa-carrageenan. Common post-harvest handling technique involves sun-drying of harvested seaweed on platforms at the farms. Quantity and quality of carrageenan varies depending on the duration and care taken during the post-harvest handling of the raw seaweed. In this study, dynamics of moisture content, water activity index (aw), carrageenan yield, and carrageenan quality were investigated by subjecting the seaweed to three post-harvest methods: (1) freeze-drying (FD), (2) shade-drying (SD), and (3) direct sun-drying (DSD). Seaweed dried under FD and SD produced high yield (56–58 %), superior gel strength (1,454–1,424 g cm^?2), high viscosity (57–58 cPs), and low syneresis (15–17 %). But, carrageenan extracted from DSD seaweed gave 28 % lower yield, 38 % lower gel strength, 27 % lower viscosity, and 8–9 % higher syneresis. In addition, gelling temperature and melting temperature of the DSD carrageenan were lower by 4 and 9 °C, respectively. Molecular size analyses of carrageenan extracted from seaweed dried under FD and SD contained carrageenan of 700 KDa (80 %) and 200 KDa (4–10 %). However, carrageenan extracted from DSD seaweed contained smaller carrageenan molecules, 460 KDa (55 %), 210 KDa (25 %), and <100 KDa (20 %). Further, scanning electron microscope images illustrated the severe effects of DSD on the morphology of seaweed cells. Therefore, SD technique was found to be the best post-harvest processing technique that gave quality carrageenan in a high quantity. Due to its simplicity and low cost, it is a practical approach to be practiced in southeast Asian countries.     

Nutritional study of Kapparazii powderTM as a food ingredient

Kappaphycus alvarezii is one of the most important commercial sources of carrageenan. Red seaweeds are found in tropical areas, and K. alvarezii is famous for its high growth rate among other tropical red seaweeds. This study was conducted to produce Kapparazii powder^TM, a product comprised of high amount of carrageenan with valuable nutrients from K. alvarezii found in Sabah, Malaysia. Spray drying and an environmentally friendly process without using chemicals were employed to produce Kapparazii powder^TM. Physicochemical properties of Kapparazii powder^TM such as proximate composition (moisture, protein, lipid, ash, and crude fiber), mineral content, heavy metals, vitamins, amino acid, color, viscosity, gel strength, swelling capacity, and water and oil holding capacity were evaluated. Kapparazii powder^TM contained moisture (4.69?±?0.03 %), protein (5.11?±?0.02 %), lipid (1.00?±?0.02 %), ash (14.52?±?0.01 %), and crude fiber (0.93?±?0.02 %). Color analysis of Kapparazii powder^TM showed that lightness (L ^*)?=?89.51?±?0.02, redness (a ^*)?=??1.27?±?0.03, and yellowness (b^*)?=?5.49?±?0.02. The value of viscosity, gel strength, swelling capacity, and water and oil holding capacity of the Kapparazii powder^TM were 0.06?±?0.00 Pa.s, 82.77?±?3.66 gf, 100?±?0.00 mL.g^?1, 4.67?±?0.58 g.g^?1, and 5.11?±?0.36 g.g^?1, respectively. Moreover, Kapparazii powder^TM did not inhibit proliferation of L929 cells after 24 h of exposure at the highest concentration (2 mg.mL^?1). In conclusion, the Kapparazii powder^TM as a source of high nutrient hydrocolloid suggested on the point of healthy ingredient for food industry application.     

Seasonal variation of carrageenan yield,gel strength and viscosity in Sarcopeltis (ex Gigartina) skottsbergii from Southern Chile

Chile is one of the top carrageenan producers worldwide, and Sarcopeltis (ex Gigartina) skottsbergii one of the topmost exploited carrageenophytes from the wild in the world. Total yield, gel strength and viscosity from two contrasting environments Calbuco and Ancud (Inner and Outer Sea, Chile) were estimated monthly in approximately 2 years for this species. While carrageenan yields did not show differences between localities, gametophytes in spring–summer had 15% higher, compared to tetrasporophytes. Sizes (frond surface) normally did not affect carrageenan yields. Gametophytes showed clear differences in gel strength between seasons, but not between localities, with maximum peaks during winter–spring months in Calbuco and autumn-winter months in Ancud. Seasonal variations in viscosity were also significant. While gametophyte viscosity did not exceed 120 cPs, tetrasporophytes reached 1400 cPs in Calbuco and 1000 cPs in Ancud. More remarkably, a positive correlation between viscosity and gel strength was found in S. skottsbergii gametophytes, which is significantly different between both localities. These results suggest that selective harvesting in spring–summer should be preferred to optimize cost–benefit of harvesting activities and subsequent carrageenan productivity.     

Carrageenan of <Emphasis Type="Italic">Eucheuma isiforme</Emphasis> (Solieriaceae,Rhodophyta) from Nicaragua

The yield and physicochemical properties of native and alkali treated carrageenan from Eucheuma isiforme harvested from the Nicaraguan coast were investigated. The native carrageenan yield was 57.2% of dry weight and decreased to 43.5% when the alga was alkali treated. Native carrageenan viscosities showed significant differences between native (144.6 ± 3.3 cPs) and treated carrageenan (113.9 ± 2.6 cPs) (p < 0.01). Alkali treatment reduced carrageenan sulphate content by 19.3% and increased 3,6 AG content by 13%. Alkali-treated carrageenan formed very weak gels in 1.5% solutions (<50 g cm⁻²). Chemical analysis and FTIR spectra revealed that Eucheuma isiforme from Nicaragua is a good source of relatively pure iota-carrageenan with sufficient quality to serve as a substitute for traditional iota-carrageenan sources.     

Optimization of agar extraction from local seaweed species,Gracilaria salicornia in Tanzania

This study aimed to develop agar extraction protocols for Gracilaria salicornia from Tanzania and investigate its physico‐chemical characteristics. A 3³ factorial experimental design was used in the extraction of agar whereby three independent variables of NaOH concentration (10, 20 and 30% w/v), alkali pre‐treatment duration (0.5, 1 and 2 h) and extraction temperatures (115, 120 and 125°C) were used to determine the optimum conditions for production of high‐quality agar. Agar yield, gel strength, sulfate content, gelling and melting temperatures were evaluated as dependent variables. The optimal condition was observed at 30% NaOH concentration, 2 h alkali pre‐treatment duration and 120°C extraction temperature. The yield, gel strength, sulfate content, gelling and melting temperatures of the agar obtained under these conditions were 26.9 ± 0.7%, 510.3 ± 16.2 g cm^?2, 0.29 ± 0.04%, 39.3°C and 88.4°C, respectively. These properties are very close to that of imported commercial agar. It was concluded that the local agar is capable of replacing imported agar for most general purposes. This offers a new possibility of using quality local agar in place of commercial agar.     

Effects of a commercial extract of the brown alga Ascophyllum nodosum on the biomass production of Kappaphycus alvarezii (Doty) Doty ex P. C. Silva and its carrageenan yield and gel quality cultivated in Brazil

Despite of its success, the carrageenan industry has had to cope with difficulties due to epiphyte infestations and diseases known as ice-ice. Some promising results in respect of biomass production, carrageenan yield, and protection epiphytes were obtained using a powdered extract of the brown alga Ascophyllum nodosum in Kappaphycus alvarezii seedling production. This study focused on the effects of the A. nodosum extract on the treatment of K. alvarezii cultivated on commercial floating rafts not only to evaluate improvements demonstrated in vitro but also the effects on the quality of the carrageenan. The seedlings were treated in an A. nodosum extract solution and placed alongside their controls on commercial floating rafts using the tubular net technique. Daily growth rate, carrageenan yield, gel strength, and gel viscosity were obtained over 20 and/or 40 days. After 20 days, daily growth rates showed no significant difference (p?=?0.44), while the carrageenan yield was higher in samples that were treated with the A. nodosum solution (p?<?0.001). After 40 days, both daily growth rate (p?=?000.7) and carrageenan yield (p?=?0.009) were higher in treated samples; however, gel strength was higher in control samples (p?=?0.03) as viscosity was also highest in the samples which had not been treated (p?<?0.001). The use of the A. nodosum extract treatment on the cultivation in situ of K. alvarezii was positive since after 40 days when the daily growth rate and carrageenan yield increased. In spite of the negative effect on the quality of the semi-refined carrageenan, the values were within commercial standards.     

Spatial and temporal variations of Chondrus crispus (Gigartinaceae, Rhodophyta) carrageenan content in natural populations from Galicia (NW Spain)

Qualitative and quantitative differences in carrageenan composition of gametophytes and tetrasporophytes of Chondrus crispus were observed in this study. Carrageenans in gametophytes belong to the kappa family (κ-, ι-, ν- and μ-carrageenan). The dominant fractions were κ- and ι-carrageenan (more than 50% of the total carrageenans). In tetrasporophytes, the presence of λ-carrageenan was confirmed. Carrageenan content in gametophytes (37.4?±?1.68% DW) was higher than in tetrasporophytes (29.13?±?0.76% DW). Spatial and temporal variation in carrageenan content in both life cycle phases appears to be related mainly to seawater and air temperatures, insolation, water movement and desiccation. The highest values of carrageenan content were recorded in those localities where higher values of precipitation, wind speed or water movement occurred. A bimodal temporal pattern on carrageenan content was observed. Fronds showed a high carrageenan content in spring and autumn. During these seasons, the content was over 40% in gametophytes and 30% in the tetrasporophytes. In summer and winter, these values down in both life cycle phases below 30%. In general the highest carrageenan contents were related to highest seawater temperatures. On the contrary, high air temperature and high insolation appeared to be unfavourable for carrageenan production. GLM models were obtained to predict carrageenan production from natural C. crispus populations, along Galician coast.     

Latitudinal variations of the yield and quality of agar from <Emphasis Type="Italic">Gelidium robustum</Emphasis> (Gelidiales,Rhodophyta) from the main commercial harvest beds along the western coast of the Baja California Peninsula,Mexico

The yield and quality of agar from Gelidium robustum from the main commercial harvest beds along the western coast of the Baja California Peninsula (Mexico) were evaluated within a latitudinal range of about 800 km (31°47′N to 27°05′N). Samples from six locations, Bahía Todos Santos, El Rosario, Isla de Cedros, Islas San Benito, Punta Eugenia, and Bahía Asunción, were analyzed. Bryozoan, protein, and agar content in the seaweed were estimated. The agar quality was determined by the content of 3,6-anhydrogalactose, sulfate, gel strength, and gelling and melting temperature. All the values of these variables were correlated and then with the satellite-derived data of the sea surface temperature (SST), net primary production (NPP), and photosynthetic active radiation (PAR) measured at each harvest bed during the summer months (June, July, and August) of 2000. In the northern and central region, the agar yield was 35% to 37% (Bahía Todos Santos, El Rosario, Isla de Cedros, and Islas San Benito), whereas lower yields were obtained from the southern beds (Punta Eugenia and Bahía Asunción). In contrast, the agar quality increased from the northern to the southern beds. A lower gel strength was obtained from Bahía Todos Santos and El Rosario (268 ± 16 and 205 ± 5 gcm⁻²) with a higher gel strength obtained from Isla de Cedros, Islas San Benito, and Bahía Asunción (384 to 444 ± 25 gcm⁻²). Yield was not correlated with the bryozoan content but was inversely correlated with the protein content in the seaweed. The sulfate content in the agar was inversely correlated with the gel strength and with the melting temperature. The 3,6-anhydrogalactose content showed slight variations among harvested beds. Analysis of satellite-derived data showed an equatorward increase of the SST, NPP, and PAR. The agar content correlated inversely with the equatorward increase of the NPP, whereas agar quality, i.e., gel strength, correlated positively with the NPP and PAR. No significant effects were observed on the yield and quality of agar with the latitudinal change of the SST.     

Characterization of Carrageenan Extracted from <Emphasis Type="Italic">Hypnea bryoides</Emphasis> in Oman

Carrageenophyte red seaweed from Oman, Hypnea bryoides, extracted using three different processes: an aqueous, a mild alkaline, and a more vigorous alkaline extraction was investigated. The resulting extract precipitated by alcohol was subject to chemical and rheological measurements. The total carbohydrate [ranged from 36.78 to 41.65 g/100 g], and ash [39.04 to 43.11 g/100 g] were the most abundant components in H. bryoides and contrary to the two, lipid content was found at a minimum [ranging from 2.95 to 3.38 g/100 g]. Alkali treatment with NaOH allowed complete conversion of kappa (κ) carrageenan form as detected by FTIR analysis. Total yield by alkali treatments gave higher yields (33%) compared with aqueous treatments (12%). However, subsequent aqueous treatment produced mixed carrageenan (μ and κ) with higher molecular weight compared with the alkali treatments which produced single carrageenan form (κ) with molecular weight of 4.1 × 10⁵ Da. The effects of thermal history on gel–sol and sol–gel transition were investigated by differential scanning calorimeter (DSC) and rheology on a pure sample and 1.5% κ-carrageenan mixture added with 30 mM KCl. Transition temperatures from DSC and rheology showed comparable results and were in good agreement with those previously reported.     

The farmed Eucheuma species (Gigartinales,Rhodophyta) in Danajon Reef,Philippines: carrageenan properties

Six cultured strains of Eucheuma denticulatum and E. alvarezii, from which stocks can be selected for the development of a Eucheuma seedling bank, were tested for their carrageenan quality from June to November 1988. Percent yield of all the varieties taken together was apparently higher in June, becoming lower in November (regression, r –0.785, probability, p 0.001). Stepwise regression analysis was done to determine the existence of any relationship between any of the following parameters: gel strength, viscosity, sulfate content, month of sampling, and yield, whether taken individually or in combination. Results show variations of the yield with the month of sampling. ANOVA was performed to test whether there are differences in sulfate levels, gel strength, and viscosity between the Eucheuma alvarezii morphotypes. There was no significant difference between the green and the brown types.     

Purification,Crystallization and Some Properties of Intracellular Pullulanase from Aerobacter aerogenes

Intracellular pullulanase was entirely extracted with sodium dodecylsulfate from the cells and was purified by means of ammonium sulfate fractionation and DEAE-cellulose and Sephadex chromatography. Crystalline pullulanase was precipitated with saturated ammonium sulfate solution. Intracellular pullulanase was purified over 150 fold in 17% yield to a final specific activity of 7000 per mg protein from the enzyme solution obtained by SDS-extraction. On ultracentrifugation analysis, the enzyme showed a symmetrical peak. The sedimentation coefficient, s_{20, w} was 6.29 S. Polyacrylamide disc electrophoresis gave a main band and a sub-band, and both showed activity. Molecular weight of intracellular pullulanase was estimated to be (8±1) × 10,000 from gel filtration with Sephadex G-200 and to be (9±1) × 10,000 from sedimentation equilibrium. These values were higher than that (6~7 × 10,000) of extracellular pullulanase. Both enzymes differed slightly in thermal- and pH-stabilities.     

Effect of the commercial extract of the brown alga Ascophyllum nodosum Mont. on Kappaphycus alvarezii (Doty) Doty ex P.C. Silva in situ submitted to lethal temperatures

Kappaphycus alvarezii is being introduced in several countries and in some of them there is a need to adapt this cultivation to periods with lethal temperatures, such as the 16–18 °C that occurs in the winter in southern Brazil. Moreover, there is the need to maintain the seedlings during this lethal temperature period. Considering the promising results obtained with the commercial powder extract of Ascophyllum nodosum (Acadian marine plant extract powder—AMPEP) treatment in the cultivation of K. alvarezii in vitro and in the sea allowing more resistance to epiphytes and increasing the growth rate and carrageenan yield, it was hypothesized that seedlings previously subjected to an AMPEP treatment could be more resilient to lethal temperatures. The daily growth rate and carrageenan yield and gel quality (gel strength and gel viscosity) of K. alvarezii in vitro previously treated with AMPEP were analyzed under temperature stress. The daily growth rates and the gel strengths of the AMPEP-treated samples were increased. In spite of the lower carrageenan yield and lower gel viscosity, the values were within the ones accepted by the carrageenan industry. Thus, the treatment of the seedlings of the K. alvarezii with AMPEP solution can be used as an alternative to lower temperature effects on crops as a preventive action for the cultivation of the seedlings in tanks and in the sea in periods of low temperatures at sea.     

Influence of alkali treatment on agar from Gracilaria cornea from Yucatán, México

The effect of alkali treatments on the yield, rheological and chemical properties of agar from Gracilaria cornea growing along the Yucatáncoast were studied in order to evaluate its potential for industrial use inan attractive economic standpoint. Alkali treatment was carried out with NaOH concentrations of 0.5%, 1%, 3% and 5% in a water bath at 80, 85 and 90 °C. Agar yield, gel strength, gelling and melting temperatures, sulphate, 3,6-anhydro-galactose and ash content weredetermined. The different combinations of NaOH concentration and treatment temperature strongly influenced agar characteristics. There was a variation in the agar content for all NaOH treatments and temperature combinations, ranging between 14.5% to 22.1%. Although the yields obtained for 0.5% NaOH at all temperatures and 1% NaOH at 80 and 85°C were higher than those required by the industry, the physical and chemical characteristics of the agar were similar to those obtained fornative agar from the same species. The gel strengths, sulphate content and gelation hysteresis obtained with agar from the 1% NaOH treatment at 90 °C are in the range required by the food industry. Treatments with 3% and 5% NaOH at all temperatures improved significantly the agar quality giving higher gel strengths (974–1758 g cm ^-2) than those reported for other Gracilaria species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Qualitative and quantitative analysis of carrageenan content in gametophytes of Mastocarpus stellatus (Stackhouse) Guiry along Galician coast (NW Spain)

Qualitative and quantitative differences in carrageenan composition of gametophytes of the rhodophyte Mastocarpus stellatus (Gigartinales) were observed in this study. Carrageenans in gametophytes belong to the kappa family (κ-, ι-, ν-, μ-carrageenan). The dominant fractions were κ- and ι-carrageenan (more than 80 % of the total carrageenans). Mean total carrageenan content in gametophytes was of 37.32?±?1.21 % DW. Spatial and seasonal variations were observed, mainly related to changes on environmental and oceanographic factors and the role of carrageenans in adapting the fronds to these changes. Maximum values in carrageenan content were observed for San Román (Biscay Bay) in May and for Laxe and Mougás (Atlantic coast) in June. The results of this study indicated that spatial differences in carrageenan content were due to interactions of different factors, rather than the effect of a single factor. Fronds from San Román had higher carrageenan content (43.23?±?1.87 % DW) than those collected at two sites of the Atlantic coast, Mougás and Laxe (32.20?±?1.14 % DW). San Román is exposed to the open sea, windy and oriented to the north, and the water temperature is higher in summer than in the Atlantic coast. However, seasonal variations in carrageenan content resulted to be more related to other factors directly correlated with the input of energy in the ecosystems (irradiance, sunshine hours and insolation). Thus, carrageenan content began to increase in early spring when the number of sunlight hours increased. Maximum values were reached in late spring or early summer, just before maximum values of irradiance and air temperature were achieved.     

Microbial protein from leguminous and non-leguminous substrates

The biodegradation of leguminous and non-leguminous organic materials by Pleurotus sajor-caju and P. ostreatus was studied. Comparisons were made between mushroom yield on both types of substrates. The conversion percentage from dry substrate to fresh mushroom (biological efficiency) was determined. Mushrooms were analyzed for their protein content, carbohydrates, percentages of ash, fat content and crude fibre. The energy value of fruit bodies was computed. The yield obtained from leguminous substrates was significantly high as compared to that yield which was obtained from non-leguminous substrates. The lowest yield of P. sajor caju (10 g ± 0.3 g) and P. ostreatus (6.5 g ± 1.2 g) was obtained using the Bougainuillea substrate and the highest one (519 g ± 16 g, P. sajor-caju and 488 g ± 18 g, P. ostreatus) using nitrogen-fixing leguminous Leucaena leucocepholea. The nitrogen content in fruit bodies was found to be higher with leguminous substrate than with non-leguminous ones.     

Seasonal variation in growth and carrageenan yield in cultivated Kappaphycus alvarezii (Doty) Doty on the coastal waters of Ramanathapuram district,Tamil Nadu

Kappaphycus alvarezii, a kappa carrageenan yielding red seaweed, was cultivated in Indian subtropical waters on the Palk Bay side of Bay of Bengal in Ramanathapuram district, Tamil Nadu, at three different sites: Vedalai, Munaikadu, and Thonithurai, for 1 year from April 2011 to March 2012. The maximum crop yields of 416 ± 51 and 550 ± 41 FW raft^?1 were recorded at Vedalai and Munaikadu, respectively, in December 2011, whereas a maximum of 326 ± 49 FW raft^?1 was recorded at Thonithurai in April 2011. Similarly, the maximum daily growth rates (DGRs) of 4.30 ± 0.51 % and 4.92 ± 0.40 % were obtained at Vedalai and Munaikadu, respectively, in December 2011, and 3.76 ± 0.48 % was recorded at Thonithurai in April 2011. Variations in environmental parameters like seawater temperature, salinity, nitrate, and phosphate were found to influence the growth of the seaweed. The maximum carrageenan content as a percentage of dry weight was 29.30 ± 0.61 % (Vedalai), 31.00 ± 0.71 % (Munaikadu), and 29.10 ± 1.12 % (Thonithurai) in March 2012. The data on moisture content (%), clean anhydrous weed/salt ratio, and carrageenan yield obtained in this study fulfilled those of international standards. Further, the results indicated that large-scale cultivation by either NGOs or self-help groups (SHGs) may be taken up along the coastal waters for the benefit of the poverty-stricken coastal people as their livelihood, as the growth rate obtained in this study compared well with that recommended for commercial cultivation elsewhere.     

The effects of selected cultivation conditions on the carrageenan characteristics of <Emphasis Type="Italic">Kappaphycus alvarezii</Emphasis> (Rhodophyta,Solieriaceae) in Ubatuba Bay,São Paulo,Brazil

The yield and the quality of carrageenan depend, among other things, on the cultivar or strain and on the cultivation and processing techniques. This work presents carrageenan yields and some properties of Kappaphycus alvarezii under selected cultivation conditions i.e. cultivation period, depth and planting density. Growth rates (GR) ranged from 5.2–7.2% day⁻¹, with the highest GR at 28 days, at 0–0.5 m depth, and planting density of 12 and 8.4 plants m⁻². Highest productivity was observed in samples after 44 and 59 day cultivation period, which were grown at 0–0.5 m depth, and a planting density of 24 plants m⁻². Carrageenan yields, iota fraction, viscosity, molecular weight and gel strength were measured. A cultivation period of 28 days during the winter had a significant higher carrageenan yield, while samples from 59 days showed a significantly higher iota fraction. Carrageenan also presented an increasing molecular weight under longer cultivation periods. A similar trend was observed for viscosity and gel strength. All samples cultivated in Brazil gave higher values when compared to a K. alvarezii commercial reference sample, with the exception of carrageenan yield values, which were lower in this study. Taking into account all parameters, the culture condition which provided the best carrageenan from a commercial perspective were 45 days of cultivation, growing at the surface, with a planting density of 12 plants m⁻². Considering that this study was performed in the least favorable season (winter), these results indicate that the site is suitable for the implementation of commercial cultivation.     

Chemical and gelling profile of ice-ice infected carrageenan from Kappaphycus striatum (Schmitz) Doty “sacol” strain (Solieriaceae, Gigartinales, Rhodophyta)

The occurrence of ice-ice disease in farmedKappaphycus spp. has tremendous implication on thecarrageenan industry in the Philippines. To elucidate the effect of thisdiseaseon the carrageenan quality, the chemical profile of carrageenan extracted fromhealthy and diseased Kappaphycus striatumsacol strain, was investigated using ¹³C and¹H NMR, FT-IR and GPC methods of analysis. The native carrageenanextracts were composed predominantly of kappa carrageenan with trace amounts ofiota and 6-O-methylated carrageenan. Structural evidence indicatesdepolymerization of carrageenan from the ice-ice infectedportion of the thallus (whitish and soft part) lowered levels of iota andmethylconstituents. This finding was correlated to its low number average molecularweight (30 kDa) value. Accordingly, appreciable decreases incarrageenan yield, gel strength and viscosity and increase in syneresis indexwere noted. On the other hand, archetype quality of kappa-carrageenan wasobserved from both healthy and uninfected portion of the diseased thalli.