Optimization of Catfish (Pangasius sp) Bone Bio-calcium Production with Different Concentrations of Citric Acid and Stirring Time Using the Response Surface Method (RSM) Approach

Abstract

Calcium is an important macro-mineral that is really needed by the body.
Calcium from fish bones can be an alternative source of calcium for those
who are allergic to milk lactose which is usually used as calcium source. The
weakness of fish bone calcium is that it still has a fishy odor, which reduces
the hedonic value of products fortified with fish bone calcium. This research
aims to determine the optimization of concentration and stirring time in citric
acid to produce bio-calcium from catfish (Pangasius sp) bones with the best
calcium content and hedonic characteristics using Response Surface
Methodology (RSM). The citric acid concentration tested was a minimum of
0.25% and a maximum of 1% with stirring times of 30, 60 and 90 min. Data
processing was carried out with the help of Design Expert 11 software. The
recommended model is the quadratic model. The recommended optimization
results for the bio-calcium production solution are a citric acid concentration
of 0.25% and a soaking time of 30 min. Verification was carried out according
to the optimization solution and gave yield results of 88.9%, particle size of
51.07 µm, calcium content 24.05; with a color hedonic value of 4.115, aroma
4.059 and overall 4.090 out of a maximum value of 5. XRD pattern showed no
difference between fishbone powder and bio-calcium with degree crystallinity
57 and 56.2%, respectively. FTIR spectra showed that both fishbone powder and
bio-calcium powder contained hydroxyapatite, however citric acid slightly removed
protein due to absence of amide 1 peaks in bio-calcium powder. Citric acid at
0.25% for 30 min helped to increase the yield and reduced some organic
compound to obtain bio-calcium powder. The proper concentration of citric acid
and stirring time yielded catfish bone bio-calcium with higher calcium content
and hedonic value.