peroxide–hydrochloric acid (1% w/w), sodium hydroxide and sodium hypochlorite, all diluted with distilled water. All chemicals were supplied by Panreac AppliChem and used without further puri ¦ cation. Temperature and inner pressure were held constant thorough the process. The different conditions tested are summarized in Table 1. The resulting product was washed, screened, crumbled, dried (temperature: 40ºC, time: 72 h) and stored at room temperature.
Table 1 Dictyota dichotoma cooking conditions.
Extraction agent
Dosage (w/w %) T (ºC) Time (min)
H 2 O 2 (alone or with HCl or SPB) 1
50
15
3
65
60
6
80
105
NaOH
1
50
15
3
65
60
6
80
105
9
80
105
12
80
105
NaClO
1
50
15
3
65
60
6
80
105
9
80
105
12
80
105
Chemical characterization The pulp obtained was characterized chemically in accordance with the common TAPPI test methods for raw materials and/or pulps (TAPPI 2019). The samples for analysis were prepared according to T 264 cm-07. Solid-liquid extractions followed T 204 cm-17 for ethanol-benzene extractives and T 207 cm-08 for hot water solubility, while the ash content was determined by means of a mu © e furnace in accordance with T 211 sp-11. The test for the determination of acid-insoluble (Klason) lignin was carried out with H 2 SO 4 24N (T 222 om-15). Between 3 and 6 repetitions were carried out for each experiment and all solutions were provided by Panreac. In the case of seaweed, as shown in previous works (Moral et al., 2019), this test targets acid-insoluble compounds that do not correspond to lignin, and thus they will be referred as Klason-positive compounds. Likewise, the results from T 203 cm-09, generally followed to estimate the content of alpha- cellulose, has to be understood here as the carbohydrate fraction which is resistant to consecutive
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