Production and Characterization of Refined Oils Obtained from Indian Oil Sardine (Sardinella longiceps)

Abstract

Crude Sardinella longiceps oil was refined in different stages such as degumming, neutralization, bleaching, and deodorization. The efficiency of these processes was evaluated on the basis of free fatty acid (FFA), peroxide (PV), p-anisidine (pAV), total oxidation (TOTOX), thiobarbituric acid reactive species (TBARS) values, Lovibond CIE-L*a*b* color analyses, and (1)H NMR or GC-MS experiments. The utilities of NMR-based proton signal characteristics as new analytical tools to understand the signature peaks and relative abundance of different fatty acids and monitoring the refining process of fish oil have been demonstrated. Phosphoric acid (1%) was found to be an effective degumming reagent to obtain oil with the lowest FFA, PV, pAV, TOTOX, and TBARS values and highest color reduction. Significant reduction in the contents of hydrocarbon functionalities as shown by the decrease in proton integral in the characteristic (1)H NMR region was demonstrated by using 1% H3PO4 during the course of the degumming process. A combination (1.25:3.75%) of activated charcoal and Fuller's earth at 3% concentration for a stirring time of 40 min was found to be effective in bleaching the sardine oil. This study demonstrated that unfavorable odor-causing components, particularly low molecular weight carbonyl compounds, could successfully be removed by the refining process. The alkane-dienals/alkanes, which cause unfavorable fishy odors, were successfully removed by distillation (100 °C) under vacuum with aqueous acetic acid solution (0.25 N) to obtain greater quality of refined sardine oil, a rich source of essential fatty acids and improved oxidative stability. The present study demonstrated that the four-stage refinement process of sardine oil resulted in a significant improvement in quality characteristics and nutritional values, particularly n-3 PUFAs, with improved fish oil characteristics for use in the pharmaceutical and functional food industries.

High Quality Oil Extracted from Sardine By‐Products as an Alternative to Whole Sardines: Production and Refining

“…Additionaly, it is interesting to note that sardine by‐product crude oil had a lower initial FFA value in comparison to whole sardine crude oil, but the addition of reagents (especially organic acids) and heating treatments during the refining process steps caused an increase in FFAs. The deodorization step reduced the FFA content in both cases probably due to vaporization of volatiles and FFAs, but the most significant decrease was obtained after the neutralization, 13.9% in S oil and 10.83% in SBP oil what is in accordance with the results reported by Chakraborty and Joseph and Crexi et al…”

“…However, the deodorization of the bleached samples carried out by distillation significantly increased the samples PVs from 2.21 meq to 4.55 meq O 2 /kg in case of sardine oil and from 2.88 to 3.78 meq O 2 /kg in case of sardine by‐product oil (Table ). Despite this increase of the PVs, the obtained values are still lower than those reported by García‐Moreno et al (from 0.33 to 5.74 meq O 2 /kg) and Chakraborty and Joseph (from 3.62 to 8.25 meq O 2 /kg). As already mentioned, the reason for this can be found in differences between used raw materials, their manipulation, and storage until processing as well as the applied refinement procedures.…”

“…As can be seen from the presented results for sardine oil, the highest FFA value, which was above 3.0%, was detected for crude oil, while significantly lower values were detected in refined oils. The FFA content of the crude oil was significantly lower than in the study of Chakraborty and Joseph on Indian oil sardine ( Sardinella longiceps ) where it was 4.4%, most likely due to differences between raw materials (species, origin, collecting season, fish tissue, etc.) and crude oil processing procedure (raw material pre‐treatment and extraction technology/equipment).…”

“…The crude oils contain some undesirable compounds, such as moisture, pigments, free fatty acids, phospholipids, minerals, off ‐flavors, etc., which affect the stability, overall quality, and consumers' acceptability of oil. Due to this a refining treatment, usually involving four major stages: Degumming (to separate phospholipids), neutralizing (to decrease acidity), bleaching (to remove coloured materials), and deodorization (to remove unwanted odor compounds), is required . Successful refining of the crude fish oil, without the loss of PUFAs, enables its further application, for example, as a dietary supplement for those who do not consume adequate amounts of fish.…”

A New Strategy to Refine Crude Indian Sardine Oil

“…Oil sardines are one of the richest and cheapest sources of n-3 polyunsaturated fatty acids n-3 PUFA such as Eicosapentaenoic acid EPA and Docosahexaenoic acid DHA 1 . The beneficial effects of n-3 PUFA in the prevention and treatment of coronary, neuromuscular, immunological disorders and allergic conditions are well documented 2 .…”