For Free Fatty Acids Research Articles

Trimethylsilyl Derivatization/Gas Chromatography as a Method to Determine the Free Fatty Acid Content of Vegetable Oils

AbstractThirty‐one samples of vegetable oils were analyzed for free fatty acid (FFA) concentration by titration against sodium hydroxide and by trimethylsilyl (TMS) derivatization followed by gas chromatography (GC). In preliminary experiments, two silylation chemistries and three GC stationary phases were tested for TMS fatty acid ester formation and separation. No ideal combination of conditions was identified; however, hexamethyldisilazane with an acid catalyst and a non‐polar J & W DB‐5 column were chosen for comparison of the two approaches. Over the range of FFA values studied (0.04–12%), the results from the two methods were highly correlated (R > +0.996) and were generally in good agreement. However, values from the chromatographic method were slightly lower than values obtained by titration for the crude oil samples (which had higher FFA levels). For oils with >0.4% FFA, the GC approach was slightly less reproducible (average coefficient of variance of ~3%) compared with the titration approach (average coefficient of variance of ~1.4%). For oils with <0.4% FFA, the coefficients of variance were higher (8–9%) and comparable between the methods.

Comparison of the adsorbent performance between rice hull ash and rice hull silica gel according to their structural differences

The microstructures of rice hull ash (RHA) and rice hull silica (RHS) were studied to understand its adsorption for free fatty acids (FFA) of degummed soybean oil. RHAs such as RHA300, RHA500, RHA700 and RHA900 were produced by heating rice hulls at temperatures of 300, 500, 700 and 900 °C, respectively. RHS500 was formed by alkali extraction of amorphous silica from RHA500. Heating temperature affects the pore development of RHAs, resulting in elongated large pores, as evident from the SEM data. A characteristic feature of amorphous material is shown in the XRD patterns of RHAs and RHS500 except RHA900. Although RHA500 has much lower surface area and pore volume compared to RHS500, it showed similar effectiveness in reducing FFA content of degummed soybean oil. It might be ascribed by higher macroporosity of RHA500 compared with RHS500, which was shown in the results of N 2 adsorption.

Esterification and transesterification on tungstated zirconia: Effect of calcination temperature

As part of ongoing efforts to investigate heterogeneous catalysts for biodiesel synthesis, the catalytic activity of the strong solid acid tungstated zirconia (WZ) was studied for the esterification of acetic acid (in both the gas and liquid phase) and the transesterification of triacetin (a synthetic triglyceride in the liquid phase) with methanol. Acetic acid and triacetin were used as model compounds for free fatty acids (FFAs) and triglycerides, respectively. Complex mixtures of FFAs and triglycerides are typical biodiesel precursors found in unrefined vegetable oils, animal fats, and waste greases. The effect of calcination temperature (400–900 °C) on the catalytic properties of WZ was investigated with the goal of determining the optimum pretreatment temperature and increasing the understanding of the nature of the active sites for esterification and transesterification. Catalyst characterization by powder X-ray diffraction, Raman spectroscopy, TGA, elemental analysis, and total BET surface area allowed us to correlate the changes in catalyst physicochemical properties with calcination temperature. Ion-exchange/titration and NH 3-TPD were used to characterize the number and strength of the acid sites. Esterification and transesterification rates (on a catalyst weight basis) increased with increasing surface WO x densities between 1.9 and 6.6 W-atoms nm −2 and then decreased for densities above 6.6 W-atoms nm −2. The growth of WO 3 crystalline species resulted in lower esterification and transesterification rates, consistent with a decrease in the number of active sites. For the catalyst that exhibited the optimum catalytic activity (calcined at 800 °C), selective poisoning of the potential catalytic centers revealed that Brønsted sites play the major role in carrying out these reactions.

Effect of rosiglitazone on factors related to endothelial dysfunction in patients with type 2 diabetes mellitus

The effect of the insulin sensitizer rosiglitazone (RSG) on biological markers of endothelial dysfunction in subjects with type 2 diabetes mellitus (T2DM) was investigated in a 12-week, multi-center, randomized, double-blind study. One hundred and thirty-six subjects aged 40–70 years, with FPG ≥7.0 and ≤15.0 mmol/l, previously treated with a single oral anti-diabetic agent or diet/exercise, were randomized to RSG 8 mg/day ( n = 65) or placebo (PBO, n = 71). Results revealed that RSG significantly reduced soluble (s)E-selectin by −10.9% ( P = 0.004) compared with PBO, but did not significantly alter soluble vascular cell adhesion molecule-1 (+0.6%, P = NS). Compared with PBO, RSG also significantly reduced plasminogen activator inhibitor-1 (−36.9%, P < 0.001), tissue plasminogen activator antigen (−22.7%, P < 0.001), FPG (−2.8 mmol/l, P < 0.001), fasting fructosamine (−42.0 mg/dl, P < 0.001). Post-prandial AUC (0–4h) for free fatty acids (FFAs) reduced by −6.5 mg/dl*h from baseline ( P = 0.03), a change that positively and significantly correlated with changes in sE-selectin ( r = 0.22, P = 0.05). The incidence of adverse events was similar in the two groups (RSG: 35.4%; PBO: 40.8%); the majority mild or moderate. These data support the hypothesis that, in patients with T2DM, rosiglitazone has beneficial effects on biological markers of endothelial dysfunction. Improvements in insulin sensitivity and decreases in FFAs may play a role in these effects.

Coagulation Tests and Selected Biochemical Analytes in Dairy Cows with Hepatic Lipidosis

The aim of this study was to determine the values and changes in conventional and optimised clotting tests, as well as in selected biochemical analytes during hepatic lipidosis in postpartum dairy cows. Ten healthy and ten Holstein cows with hepatic lipidosis were selected based upon clinical history, clinical examination, liver biopsy, flotation test and histological analysis of hepatic tissue. Prothrombin time (PT) and partial thromboplastin time (PTT) were determined in non-diluted and diluted blood plasma samples. Clotting times determined in diluted plasma samples were prolonged in cows with hepatic lipidosis and there was a difference in the PT value at both 50% and 25% plasma dilutions between both groups of animals (P = 0.004 and P = 0.001). Significant differences between healthy animals and cows with hepatic lipidosis were observed in blood serum values for free fatty acids (FFA), aspartate aminotransferase (AST) and triacyglycerols (P = 0.001, P = 0.007 and P = 0.044), respectively. FFA and liver biopsy are better diagnostic indicators for hepatic lipidosis than coagulation tests. The optimised PT is prolonged in cows with hepatic lipidosis and can detect this alteration that cannot be appreciated using conventional PT test.

Increased physical activity decreases hepatic free fatty acid uptake: a study in human monozygotic twins

Exercise is considered to be beneficial for free fatty acid (FFA) metabolism, although reports of the effects of increased physical activity on FFA uptake and oxidation in different tissues in vivo in humans have been inconsistent. To investigate the heredity-independent effects of physical activity and fitness on FFA uptake in skeletal muscle, the myocardium, and liver we used positron emission tomography (PET) in nine healthy young male monozygotic twin pairs discordant for physical activity and fitness. The cotwins with higher physical activity constituting the more active group had a similar body mass index but less body fat and 18 +/- 10% higher (P < 0.001) compared to the less active brothers with lower physical activity. Low-intensity knee-extension exercise increased skeletal muscle FFA and oxygen uptake six to 10 times compared to resting values but no differences were observed between the groups at rest or during exercise. At rest the more active group had lower hepatic FFA uptake compared to the less active group (5.5 +/- 4.3 versus 9.0 +/- 6.1 micromol (100 ml)(-1) min(-1), P = 0.04). Hepatic FFA uptake associated significantly with body fat percentage (P = 0.05). Myocardial FFA uptake was similar between the groups. In conclusion, in the absence of the confounding effects of genetic factors, moderately increased physical activity and aerobic fitness decrease body adiposity even in normal-weighted healthy young adult men. Further, increased physical activity together with decreased intra-abdominal adiposity seems to decrease hepatic FFA uptake but has no effects on skeletal muscle or myocardial FFA uptake.

Alcohol and lipid metabolism

Hepatic lipid metabolism is controlled by several master transcription factors, in particular peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and sterol response element binding protein-1 (SREBP-1). Peroxisome proliferator-activated receptor-alpha is a receptor for free fatty acids (FFA), and can activate genes involved in transport, oxidation, and export of FFA. Sterol response element binding protein-1 is a sensor for the level of cholesterol in the liver, and is able to activate genes involved in synthesis of cholesterol and FFA. Chronic ethanol treatment of cells or animals inhibited PPAR-alpha function and activated SREBP. In addition, ethanol inhibited adenosine monophosphate-dependent protein kinase (AMPK). The AMPK controls fatty acid metabolism by inhibiting acetyl-coenzyme A carboxylase, reducing malonyl-coenzyme A, and thereby permitting fatty acid transport into and oxidation in the mitochondrion. Adenosine monophosphate-dependent protein kinase was inhibited in alcohol-treated animals and cells. The mechanisms by which ethanol affects AMPK and the transcription factors are as yet incompletely understood.

Plasma Interleukin-6 Levels Are Independently Associated With Insulin Secretion in a Cohort of Italian-Caucasian Nondiabetic Subjects

We have investigated the relationships between plasma interleukin-6 (IL-6) levels and insulin sensitivity and insulin secretion in a cohort of Italian-Caucasian glucose-tolerant subjects. Insulin sensitivity was assessed by euglycemic-hyperinsulinemic clamp, and first-phase insulin secretion was measured by intravenous glucose tolerance test. Fasting plasma IL-6 concentration was negatively correlated with the rate of insulin-stimulated glucose disposal (M) (P = 0.001). The correlation remained statistically significant, while attenuated, after adjusting for sex, age, and BMI (P < 0.03); after an additional adjustment for free fatty acids (FFAs), a further attenuation was observed, but statistical significance was maintained (P < 0.044). Fasting plasma IL-6 concentration was positively correlated with first-phase insulin secretion assessed as acute insulin response (AIR) (P = 0.001). The correlation remained significant after adjusting for sex, age, and BMI (P = 0.003). To estimate the independent contribution of plasma IL-6 levels to AIR, we carried out forward stepwise linear regression analysis in a model that included sex, age, BMI, waist-to-hip ratio, FFAs, and insulin-stimulated glucose disposal. Only insulin sensitivity and plasma IL-6 concentration were independently associated with AIR, accounting, respectively, for 19.0 and 5.2% of its variation. These data indicate that IL-6 is associated in a reciprocal manner with the two pathophysiological components of type 2 diabetes, i.e., insulin resistance and insulin secretion.

Exercise Induced Energy Deficit Does Not Impact Resting Plasma Free Fatty Acids and Glycerol

Recently, negative energy balance induced by decreased energy intake was reported to cause resting plasma free fatty acid and glycerol concentrations to increase (1). Whether negative energy balance induced by increased energy expenditure affects biomarkers of lipid metabolism similarly is not known. PURPOSE: To compare effects of energy deficit induced by increased daily exercise on plasma markers of lipolyis with effects of increased exercise without energy deficit. METHODS: Fourteen men (23.4 ± 1.3 yrs, 74.0 ± 1.8 kg, 14.4 ± 1.4 % body fat, VO2peak58.2 ± 2.2 ml/kg/min) consumed a diet containing ∼55% CHO, 38% fat, and 0.9g protein/kg/d for 11 days. Day 1–4 (baseline, BL) energy intake (EI) matched EI and energy expenditure (EE) recorded the week before BL. Volunteers then added exercise at 55–65% VO2peak to expend an additional 1000 kcal/d for 7 days (EX). Seven volunteers increased EI to maintain energy balance (BAL), while seven maintained BL EI (DEF). EE was assessed by closed circuit spirometry, and body weight was recorded daily. Fasting plasma was analyzed for free fatty acid (FFA) and glycerol on days 3, 6, and 11. RESULTS: EI and EE for BAL was 3642 ± 271 and 3659 ± 276 kcal/d during BL and increased to 4594 ± 266 and 4655 ± 274 kcal/d during EX. EI for DEF was 3450 ± 97 kcal/d for BL and EX, while EE increased from 3491 ± 151 to 4447 ± 157 kcal/d for BL and EX respectively. BAL remained weight stable, while DEF lost 2.4 ± 0.21 kg (p<0.05). Resting FFA and glycerol values (mean ± SEM) are shown. * Difference between groups (p<0.05)TableThere were no differences within either group for FFA or glycerol from BL to EX. CONCLUSION: In contrast to what was observed with a one-day diet-induced energy deficit, a 7-d 1000 kcal/d exercise-induced energy deficit did not affect plasma markers of lipolysis, suggesting differential lipolytic regulation during dietary and exercise-induced energy deficit.

Physicochemical changes induced in carp ( Cyprinus carpio) fillets by high pressure processing at low temperature

Raw carp fillets ( Cyprinus carpio) were vacuum packed and pressurized at 100, 140, 180 and 200 MPa at 4 °C for 15 and 20 min, and then monitored for changes in the lipid fraction, color and electrophoretic profiles. The values of thiobarbituric acid (TBA) reactive substances in the samples increased with pressure and pressurization time. Similar results were obtained for free fatty acids (FFA) levels formed as a result of pressure treatment. The CIE color values, i.e., L ⁎ (lightness), a ⁎ (redness) and b ⁎ (yellowness) of the carp fish fillets also increased with pressure and pressurization time, and the results obtained attest to the importance of establishing treatment conditions for various fish species when processing these food products in order to minimize changes in their appearance and flavor characteristics. Industrial relevance High pressure processing is finding increasing use in the food industry because of its relative advantages versus other food processing methods in eliciting minimal changes in the flavor and nutritional qualities of the final product. High pressure treatment is able to achieve this via its effects on the two causative agents of food spoilage, namely autolysis as well as microbial growth and metabolism. High pressure processing has been used commercially to produce food products such as raw oysters, guacamole, and ham and fruit juices in the US; and to produce jams, jellies, fish and meat products, salad dressing, ham, fruit juices and yogurt in Europe and Japan. However, in spite of the notion that high pressure processing results in minimal changes in food products, it is also common knowledge that the technology induces important changes in the texture and appearance of raw fish would be influenced by temperature at which the pressurize treatment was conducted. This paper illustrates the changes induced in raw carp flesh by pressurization at different temperatures.

Extraction/fractionation and deacidification of wheat germ oil using supercritical carbon dioxide

Wheat germ oil was obtained by mechanical pressing using a small-scale screw press and by supercritical extraction in a pilot plant. With this last method, different pressures and temperatures were tested and the tocopherol concentration in the extract was monitored during extraction. Then supercritical extracted oil as well as commercial pressed oil were deacidified in a countercurrent column using supercritical carbon dioxide as solvent under different operating conditions. Samples of extract, refined oil and feed oil were analyzed for free fatty acids (FFA) and tocopherol contents. The results show that oil with a higher tocopherol content can be obtained by supercritical extraction-fractionation and that FFA can be effectively removed by countercurrent rectification while the tocopherol content is only slightly reduced.

Nonalcoholic Fatty Gallbladder Disease: The Influence of Diet in Lean and Obese Mice

The obesity epidemic has contributed to an increased prevalence of gallstones and a higher percentage of chronic acalculous cholecystitis. Obesity is associated with Type II diabetes and hyperlipidemia in murine models. In addition, we have previously demonstrated that serum glucose, insulin, cholesterol, and triglycerides correlated with gallbladder contractility in murine models. However, the relative role of insulin resistance and gallbladder fat infiltration in this phenomenon remain unclear. Therefore, we tested the hypothesis that gallbladder wall lipids are related to obesity and diet and are inversely correlated with gallbladder contractility. One hundred lean control (C7BL/6J) and 36 obese leptin-deficient (Lep(ob)) 8-week-old female mice were fed either a chow diet or a 1.0% cholesterol, 15% butterfat (high-lipid) diet for four weeks. Pooled gallbladders were then analyzed for free fatty acids (FFA), phospholipids (PL), total cholesterol (TC), and triglycerides (TG). Cholesterol/phospholipid ratios were then calculated. The Lep(ob) mice fed a chow diet had significantly higher (P < 0.01) gallbladder lipids than the three other groups. The lean mice that were fed a high-lipid diet had increased (P < 0.05) gallbladder TC compared to the lean mice on a chow diet. In addition, the cholesterol/phospholipid ratio was significantly increased (P < 0.01) in the lean mice fed a high-lipid diet compared to the other three groups. Finally, the high-lipid diet decreased gallbladder FFA (P < 0.01), PL (P = 0.08), and TC (P < 0.05) in Lep(ob) mice. These data suggest that (1) obese mice have increased gallbladder lipids; (2) a high-cholesterol, high-fat diet increases gallbladder lipids and the cholesterol/phospholipid ratio in lean mice; but (3) decreases gallbladder fatty acids, phospholipids, and cholesterol in obese mice. Prior studies have documented similarly decreased gallbladder response to neurotransmitters in obese mice on a chow diet, as well as lean and obese mice on a high-lipid diet. Therefore, we conclude that leptin-deficient obesity and/or a high-fat diet causes nonalcoholic fatty gallbladder disease, which is manifested by diminished gallbladder contractility.

Detection of free fatty acids following a conditioned taste aversion in rats

A gustatory transduction mechanism for free fatty acids (FFAs) has been described in isolated rat taste receptor cells; however, the ability of behaving rats to detect FFAs has not been characterized. Through conditioned taste aversion (CTA) methodology, this study defines the ability of rats to detect and avoid the two principal FFA components of corn oil, linoleic and oleic acid. Following taste aversion conditioning, rats avoided both linoleic and oleic acid at greater than or equal to 66 μM and failed to avoid either 44 μM linoleic or oleic acid. Rats demonstrated generalized avoidances between 88 μM linoleic and oleic acid irrespective of presenting the FFAs as either unesterified acids dissolved in 5 mM ethanol or aqueous sodium salts, sodium linoleate and sodium oleate. Following a CTA to linoleic acid, rats did not show generalized avoidance of NaCl or ethanol, two potentially concomitant tastants in the oral cavity. A CTA to linoleic or oleic acid did produce a generalized avoidance to the other FFA. These results support the ability of rats to detect linoleic and oleic acid (> 44 μM) and suggest that the two FFAs share common orosensory properties. Furthermore, it is unlikely that the detection of the FFAs is due to an enhancement of other concomitant tastants such as saliva or the delivery solution.

Multivariate determination of free fatty acids and moisture in fish oils by partial least-squares regression and near-infrared spectroscopy

The oxidative and hydrolytic degradation of lipids in fish oil was monitored using partial least-squares (PLS) regression and near-infrared reflectance (NIR) spectroscopy. One hundred and sixty ( n=160) fish oil samples from a fishmeal factory were scanned in transflectance by an NIR monochromator instrument (1100–2500 nm). Calibration models were performed for free fatty acids (FFA), moisture (M), peroxide value (PV) and anisidine value (AV). Coefficients of determination in calibration ( R 2) and standard errors of cross validation (SECV) were 0.96 (SECV: 0.59) and 0.94 (SECV: 0.03) for FFA and M in g/kg, respectively. The accuracy of the NIR calibration models were tested using a validation set, yielding coefficients of correlation ( r) and standard errors of prediction (SEP) of 0.98 (SEP: 0.50) and 0.80 (SEP: 0.05) for FFA and M in g/kg, respectively. Poor accuracy ( R 2<0.80) was obtained for the NIR calibration models developed for PV and AV. The paper demonstrates that fish oil hydrolytic degradation of lipids, which seriously affect oil use and storage under industrial conditions, can be successfully monitored using PLS regression and NIR spectroscopy by the fishmeal industry.

Decrease in serum leptin after prolonged physical activity in men.

This study was designed to determine whether serum leptin levels were affected by a 5-d military course after 3 wk of combat training. 26 male soldiers (mean age = 21 +/- 2 yr) were examined at the beginning of the training program and just at the end of the 5-d course. The combination of continuous heavy physical activity and sleep deprivation led to energy deficiency. Blood samples were analyzed for serum leptin, insulin, cortisol, adrenocorticotropin (ACTH), and testosterone; plasma was analyzed for free fatty acids (FFA), glycerol, glucose, and catecholamines. At the end of the 5-d course, there was a significant reduction in serum leptin (0.40 +/- 0.04 ng x mL(-1) versus 1.47 +/- 0.14 ng x mL(-1), < 0.001), i.e., a mean decrease of 67.00 +/- 3.75%. Plasma norepinephrine and dopamine rose significantly from 296 +/- 17 ng x L(-1) to 672 +/- 48 ng x L(-1) and 23 +/- 3 ng x L(-1) to 40 +/- 5 ng x L(-1) ( < 0.001 and < 0.01, respectively), whereas epinephrine remained unchanged. Serum concentrations of the anabolic hormone, insulin, fell from 31.17 +/- 3.03 microU x mL(-1) to 17.79 +/- 1.58 microU x mL(-1) ( < 0.001), whereas plasma FFA and glycerol were increased ( < 0.001, < 0.05, respectively). A statistically significant correlation appeared between the changes in leptin and insulin (r = 0.5306, < 0.01). Serum testosterone decreased significantly ( < 0.001), whereas serum cortisol, ACTH, and plasma glucose were unchanged at the end of the course. The training program had no significant effect on mean body mass index. A 4-wk strenuous military training program, which induced an energy deficiency, reduced serum leptin to a third of normal levels. The decrease in serum leptin was attributed to the exercise-induced elevation in catecholamines and hypoinsulinemia.

Active Treatment of Frying Oil for Enhanced Fry‐life

ABSTRACTFrying experiments were conducted simulating food service operation for 10 d, with and without active treatment of frying medium. Oil samples were analyzed for free fatty acids (FFA), color, food oil sensor (FOS) readings, chemiluminescence, and total polar compounds (TPC). Daily treatment of frying oil with adsorbent was found to extend the frying life of oil by reducing the accumulation of FFA, TPC, and AOCS ‘R’ color value by 72%, 30%, and 52%, respectively.

Leg gas exchange, release of glycerol, and uptake of fats after two minutes bicycling to exhaustion

It is not known to what extent the muscles use fats and carbohydrates as substrate for oxidation after intense, anaerobic types of bicycling. Six healthy young men therefore bicycled at constant power for 2 min to exhaustion. Blood was drawn from indwelling catheters in the femoral artery and vein at intervals during the 1-h postexercise recovery. The blood samples were analysed for concentrations of O 2 and CO 2, and for free fatty acids (FFA), triacylglycerols (TG), and glycerol in plasma. The blood flow was also measured, and the rate of leg uptake of FFA, TG, and O 2 and the release of CO 2 and glycerol as well as its gas exchange ratio were calculated and integrated over the recovery period. The leg gas exchange ratio integrated over the exercise plus 1-h recovery period was 0.67 - 0.06 (mean - SEM), suggesting pure fat oxidation. There was no statistically significant arterial - femoral-venous difference of FFA across the leg. The concentration of TG in plasma fell by 0.18 - 0.09 mmol L -1 (32%) during the first 10 min of the recovery period, and the leg took up 18 - 8 mumol TG kg -1 body mass (bm) during the whole 1-h recovery period. Free glycerol was released from the leg throughout the recovery period in excess of that released from hydrolysis of TG from plasma, suggesting that 30 - 10 mumol TG kg -1 bm was hydrolysed, probably from intramuscular stores. If fully oxidized, the triacylglycerols hydrolysed can account for 101% of the measured O 2 uptake. Thus, muscle seems to use only triacylglycerols as substrate for its oxidative energy release after intense exercise.

Studies on the Mode of Uptake of Plasma Glucose, Acetate, β-hydroxybutyrate Triglyceride Fatty Acids and Glycerol by the Mammary Gland of Crossbred Holstein Cattle Feeding on Different Types of Roughage

The present experiment was carried out to study the utilization of substrates in the mammary gland of crossbred Holstein Friesian during feeding on different types of roughage. Sixteen pregnant crossbred Holstein heifers consisted of two breed types of eight animals each; Holstein Friesian×Red Sindhi (50:50=50%HF) and Holstein Friesian×Red Sindhi (87.5:12.5=87.5%HF). Animals were divided into four groups of the same breed type in each group which were fed with either rice straw treated with 5% urea or pangola hay (Digitaria decumbens) as the source of roughage throughout the experiments. Four consecutive experimental periods were carried out in late pregnancy (20-23 days before parturition), early lactation (30 days postpartum), mid-lactation (120 days postpartum) and late lactation (210 days postpartum). Measurement of mammary blood flow in combining with measurement of AV difference was performed for the mammary uptake of substrates. In the period of lactation, udder blood flow was nearly three times higher than that of late pregnant period (p<0.05) in both 50%HF and 87.5%HF feeding on either hay or urea treated rice straw. During mid- and late lactation of both groups of 87.5%HF animals, mammary blood flow and milk yield showed decrease when compared to those during the early lactating period while the trends for persistency were apparent in both groups of 50%HF animals throughout experimental periods. The mean arterial plasma concentrations of glucose, acetate, β-hydroxybutyrate and free glycerol in each group remained constant throughout experimental periods. During late pregnancy in all groups, the AV difference and extraction ratio of glucose, β-hydroxybutyrate and triacylglycerol across the mammary gland markedly lowered (p<0.05), which coincided with a lower net uptake by the mammary gland in comparison to the early lactating period. The mean arterial plasma concentration, AV difference and extraction ratio for acetate showed no significant differences between late pregnancy and the early lactating period. The AV difference of free glycerol showed apparent release from mammary tissue during late pregnancy in all groups. In mid- and late lactation, the mammary uptake for glucose, acetate and β-hydroxybutyrate in both groups of 87.5%HF animals showed apparent decrease as compared to that in the early lactating period, whereas no appearances were observed in 50%HF animals feeding either hay or urea treated rice straw. The mean arterial plasma concentrations for free fatty acid (FFA) and triacylglycerol (C16 to C18) were higher in late pregnancy than in early lactation in both types of crossbred animals. The values of AV difference and the net uptake by the mammary gland for FFA were variable during late pregnancy and lactating periods in all groups. There were no significant differences for AV difference, extraction ratio and net uptake of triacylglycerol during lactation advance in both groups of 50%HF and 87.5%HF animals feeding either hay or urea treated rice straw. These results suggest that the adaptations to either hay or urea treated rice straw by the mammary gland of crossbred HF animals allow for an adequate nutrient supply during pregnancy and lactation. There is no difference in the mode of mammary uptake of substrates in the same crossbred animals in response to feeding hay or urea treated rice straw. The differences in utilizing nutrients by the mammary gland for milk production between 87.5%HF and 50%HF animals would be dependent on changes in both intra-mammary factors and extra-mammary factors. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 10 : 1445-1452)

Free fatty acid formation and lipid oxidation on milled rice

AbstractMilled rice was stored at 37°C and 70% humidity and sampled regularly for 50 d. Rice surface lipid was extracted with isopropanol and analyzed for free fatty acids (FFA) and conjugated diene (CD) contents. Diffuse reflectance Fourier transform infrared (DRIFTS) spectra of the rice samples were also obtained. FFA and CD levels increased together during rice storage and exhibited three distinct phases. DRIFTS identified a decrease in intensity at 1746 cm−1 (ester, −C=O) and increases in intensity at 1731 cm−1 (aldehyde, −CO) and 1714 cm−1 (fatty acid, −C=O) during storage, which correlated well with the chemical analysis data. DRIFTS spectral data were analyzed by a partial least squares regression method to identify spectral regions that correlate strongly with measured FFA and construct prediction models. Overall, the mid‐infrared region (4000–400 cm1) gave the best model (R=0.98, root mean square error of cross‐validation=0.05) and also predcted the FFA content of milled rice well. The DRIFTS technique has potential for use in studying qualitative chemical changes on the milled rice surface lipids and for predicting FFA on milled rice.

Recovery of used frying oils with adsorbent combinations: refrying and frequent oil replenishment

Treatment of used frying oils with adsorbent combinations may improve the quality of fried foods and extend the frying life of oil. Two selected combinations of four commonly used filter aids: Britesorb (Br), Hubersorb 600 (HB), Frypowder (Fr), and Magnesol (Ma) were used to recover used frying oils by vacuum filtration. The effectiveness of the adsorbent treatments were evaluated by refrying chicken fritters and breasts in the recovered used oil. After 32 h continuous frying, the parameters of treated oil subjected to adsorbent combinations F (3% HB+3% Ma+2% Fr) and B (2% HB+2% Ma+3% Br), were reduced as follows: 61.9 and 59.7%, 38.0 and 11.3%, 25.2 and 19.5%, and 9.4 and 3.5% for free fatty acids (FFA), total polar component (TPC), Foodoil Sensor (FOS) reading, and color differences (ΔE), respectively, compared to the untreated used oil. After daily treatment for 4 days, the filter aid combination F reduced the final values of FFA, TPC, FOS and color differences by 64.2, 19.1, 32.6 and 4.4%, respectively, compared to the untreated control. These adsorbent combinations may be useful in extending the life of frying oils.