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Comparative study on oxidative decomposition behavior of vegetable oils and its correlation with iodine value using thermogravimetric analysis

Saad B, Wai WT, Lim BP

J Oleo Sci, 2008;57(4):257-61.
PMID: 18332590

A comparative study of oxidative decomposition behavior of a wide range of vegetable oils and its correlation to iodine value (IV) using thermogravimetric analysis (TGA) was described. The oxidative decomposition of saturated fatty acids shows weight loss before 385 degrees C while oxidative decomposition of unsaturated fatty acids shows lower rate of weight loss (dWt/dt) compared to saturated fatty acids due to the oxidation process ('up taking ' of oxygen) involving breaking down of double bond to form primary and secondary oxidation products, which leads to some weight gain in the sample before being decomposed. The relative differences in the dWt/dt (%/min) of the both fatty acids give different decomposition steps in TGA thermogram, enabling IV to be determined through the percentage weight loss of saturated fatty acids per 100% of total sample weight (excluding weight loss from moisture and volatile compounds). Therefore, TGA method can be used as an alternative method for IV determination with no sample pre-dilution and solvent consumption. Using the TGA methods, good correlation (r = 0.9889) with standard AOCS method was achieved.

Matched MeSH terms: Iodine/analysis*
Characterization of low saturation palm oil products after continuous enzymatic interesterification and dry fractionation

Huey SM, Hock CC, Lin SW

J Food Sci, 2009 May-Jul;74(4):E177-83.
PMID: 19490322 DOI: 10.1111/j.1750-3841.2009.01122.x

The lipase-catalyzed interesterification of refined, bleached, deodorized palm olein with iodine value (IV) of 62 was studied in a pilot continuous packed-bed reactor operating at 65 degrees C. Sn-1,3 specific immobilized enzyme; Lipozyme TL IM (Thermomyces Lanuginosa) from Novozyme A/S was used in this study. The interesterification reaction produced fully solidified fats at ambient temperature due to the production of trisaturated triacylglycerols (TAG) (PPP and PPS, where P = palmitic acid, S = stearic acid). The reaction also increased the percentage of triunsaturated TAG (OLL, OLO, and OOO, where O = oleic acid, L = linoleic acid). The interesterified product was then dry fractionated at temperatures of 9, 12, 15, 18, and 21 degrees C to separate the saturated fats from the unsaturated. The results show that IV of olein increased when the fractionation temperature (T(FN)) decreased. The highest IV of olein was 72, obtained from T(FN) at 9 degrees C. After interesterification and laboratory-scale fractionation, the olein fractions contained higher unsaturation content ranging from 64.7% to 67.7% compared to the starting material (58.3%), while the saturation content was reduced from 41.7% to the range of 32.3% to 35.3%. The yields of these oleins were low with the range of 24.8% to 51.8% due to the limitation of the vacuum filtration. Ten kilograms of pilot-scale fractionation with membrane press filter was used to determine the exact olein yield. At T(FN) of 12 degrees C, 67.1% of olein with saturation content of 33.9% was obtained.

Matched MeSH terms: Iodine/analysis
Replacement of animal fat with fractionated and partially hydrogenated palm oil in beef burgers

Babji AS, Alina AR, Seri Chempaka MY, Sharmini T, Basker R, Yap SL

Int J Food Sci Nutr, 1998 Sep;49(5):327-32.
PMID: 10367001

Four formulations of burgers, prepared with 65% lean meat and 15% fat consisting of RBD palm stearin (PS), Socfat 4000P and Socfat 4100P and beef fat (BF) as control were evaluated for solid fat content (SFC), slip melting point (SMP), cooking loss, proximate analysis (moisture, fat and protein), colour, i.e. lightness ('L'), redness ('a') and yellowness ('b'), free fatty acid (FFA), iodine value (IV), thiobarbituric acid (TBA) and texture profile analysis (TPA). Sensory evaluation was carried out for texture, juiciness, aroma, oiliness and overall acceptance. SFC and SMP for raw and cooked SF4000P beef burgers were closest to BF control burgers, falling into the range of 35-40 degrees C. Cooking loss was highest for PS burgers, there were no significant differences (P > 0.05) amongst BF, SF4000P and SF4100P burgers. Proximate analysis on raw burgers showed SF4000P to contain high fat and lowest moisture contents. Objective textural measurements using texture profile analysis (TPA) for all cooked burgers showed no significant differences (P > 0.05) for springiness and cohesiveness. Variation of values among the formulations for hardness, gumminess and chewiness are explained by the differences of SFC for beef burgers with various types of fats. Raw and cooked PS burgers have the lightest 'L' values compared with other fat-substituted burgers while BF, SF4000P and SF4100P indicated no significant differences (P > 0.05) for 'L', 'a' and 'b' values. Beef fat showed the highest amount of free fatty acids (FFA) compared to palm oil samples. For the iodine value (IV), SF4000P showed the highest value which means that it contained the highest level of unsaturated fatty acids followed by PS, BF and SF4100P successively. SF4000P had the highest TBA values followed successively by BF, PS and SF4100P. For sensory evaluation, PS burgers had the least oily taste. This may be due to its high cooking loss. Taste panelists could not differentiate burgers with substituted vegetable fats against the control burgers.

Matched MeSH terms: Iodine/analysis
Fulltext The prevalence of goitre in remote inland versus coastal areas

Osman A, Zaleha MI, Letchumen R, Khalid BA

Med J Malaysia, 1995 Sep;50(3):256-62.
PMID: 8926905

The study was conducted to compare the prevalence of goitre among Malays and Aborigines in remote inland rural areas to those in coastal areas. All subjects were examined thoroughly by an experienced endocrinologist for the presence of goitre. The overall goitre prevalence in coastal areas was 6.3%; 6.0% (4/67) of Aborigines and 6.7% (4/60) of Malays were affected. However, in remote inland areas, the prevalence of goitre was almost 5 times higher compared to coastal areas. The prevalence of goitre was 30.7% in Baling; 30.2% (19/63) Aborigines and 30.8% (92/299) Malays were affected. Iodine deficiency is the most likely cause for the high prevalence of goitre in the remote inland areas.

Matched MeSH terms: Iodine/analysis
Stability evaluation of quality parameters for palm oil products at low temperature storage

Ramli NAS, Mohd Noor MA, Musa H, Ghazali R

J Sci Food Agric, 2018 Jul;98(9):3351-3362.
PMID: 29250790 DOI: 10.1002/jsfa.8839

BACKGROUND: Palm oil is one of the major oils and fats produced and traded worldwide. The value of palm oil products is mainly influenced by their quality. According to ISO 17025:2005, accredited laboratories require a quality control procedure with respect to monitoring the validity of tests for determination of quality parameters. This includes the regular use of internal quality control using secondary reference materials. Unfortunately, palm oil reference materials are not currently available. To establish internal quality control samples, the stability of quality parameters needs to be evaluated.
RESULTS: In the present study, the stability of quality parameters for palm oil products was examined over 10 months at low temperature storage (6 ± 2 °C). The palm oil products tested included crude palm oil (CPO); refined, bleached and deodorized (RBD) palm oil (RBDPO); RBD palm olein (RBDPOo); and RBD palm stearin (RBDPS). The quality parameters of the oils [i.e. moisture content, free fatty acid content (FFA), iodine value (IV), fatty acids composition (FAC) and slip melting point (SMP)] were determined prior to and throughout the storage period. The moisture, FFA, IV, FAC and SMP for palm oil products changed significantly (P 0.05). The stability study indicated that the quality of the palm oil products was stable within the specified limits throughout the storage period at low temperature.
CONCLUSION: The storage conditions preserved the quality of palm oil products throughout the storage period. These findings qualify the use of the palm oil products CPO, RBDPO, RBDPOo and RBDPS as control samples in the validation of test results. © 2017 Society of Chemical Industry.

Matched MeSH terms: Iodine/analysis
Endemic goiter in Sarawak, Borneo Island; prevalence and pathogenesis

Ogihara T, Oki K, Iida Y, Hayashi S

Endocrinol. Jpn., 1972 Jun;19(3):285-93.
PMID: 4117947
Matched MeSH terms: Iodine/analysis