Janet Paterson

Folate assay of foods by traditional and tri-enzyme treatments using cryoprotected Lactobacillus casei

Variables affecting the efficacy of the microbiological assay of folate in foods were examined. Spinach, fortified bread and two ready-to-eat breakfast cereals were extracted with or without autoclaving and centrifugation. Autoclaving and centrifugation lowered the yield of total folate in all foods. The food sample, after digestion with protease and α-amylase was deconjugated with chicken pancreas or human plasma (tri-enzyme treatment) or simply with conjugase alone (tradition single enzyme treatment). The tri-enzyme treatment was a significant improvement over the single enzyme treatment only in fortified bread. Deconjugation with chicken pancreas gave a significantly higher folate value than did human plasma in all foods except spinach. Folate assay by cryoprotected frozen Lactobacillus casei was compared with serially sub-cultured inocula. Using the cryoprotected frozen inoculum took a shorter time, was less tedious, gave better reproducibility and was more economical than using the conventional serial culture. The effects of the size of test tubes on the growth of culture and the wavelength at which turbidity was measured to achieve maximum detection were also investigated. L.casei grew faster in small tubes than in larger ones. The absorbance peak at 540 nm was higher than that at 620 nm.

Edible coating materials—their properties and use in the fortification of rice with folic acid

Abstract This study investigated the technical feasibility of adding folic acid on to rice and coating with edible polymers. The coating solutions were cast into film and their properties were investigated. A concentrated premix of rice was prepared in a rotating coating pan by spraying first with folic acid solution, and then with polymer solutions and drying. The fortified rice premixes were evaluated for washing and cooking losses. The loss of folic acid in washing was lowest in rice premixes coated with ethyl cellulose followed by pectin, composite mixtures of locust bean and other coating materials with highest loss in gum arabic coated rice. No edible polymer could satisfactorily retain folic acid during boiling in excess water. Edible polymers failed to mask the yellow color of folic acid and additional masking agent was needed. The premixes had a higher water uptake ratio than raw milled rice had. Triangle tests did not show any significant difference (α=0.05) between the sensory qualities of cooked fortified rice and raw milled rice.

Interactions between phytochemicals from fruits and vegetables: Effects on bioactivities and bioavailability

ABSTRACT The combinations of two or more phytochemicals bring about changes in the ultimate biological effects and/or the bioavailability of each component. A number of mixtures of pure bioactive compounds or phytochemical-containing plant extracts provide synergy with regard to antioxidant status, anti-inflammation, anti-cancer and chemoprevention of several oxidative stress and metabolic disorders in vitro. The biological activities of food phytochemicals depend upon their bioaccessibility and bioavailability which can be affected by the presence of other food components including other bioactive constituents. The interactions between phytochemicals during intestinal absorption could result in changes in the bioavailability of the compounds, which in turn affects the intensity of their bioactivities. This paper provides an overview of combined biological effects of phytochemical mixtures derived from fruits and vegetables with a focus on anti-oxidative, anti-inflammatory and anti-carcinogenic activities. The bioavailability impairment or enhancement caused by the co-consumption of dietary phytochemicals is also discussed. Finally, research gaps for future studies on phytochemical interactions are identified.

Effect of marbling on volatile generation, oral breakdown and in mouth flavor release of grilled beef

While the positive effect of intramuscular fat (IMF) on beef tenderness is well-established, its role in flavor generation and flavor release is less defined. To increase understanding, real-time volatile generation was monitored during grilling of beefsteaks (grass and grain-fed Angus and grass-fed Wagyu) with different amounts of IMF by proton transfer reaction mass spectrometry. Volatile concentration increased significantly (p<0.001) when the IMF was >~10%, but did not differ (p>0.05) at lower IMF levels (5.2-10.2%). In vivo release of volatiles during consumption of grilled steaks was also measured using human subjects. Pre- and postswallow volatile release profiles varied according to marbling level and volatile fat solubility. In-mouth release of key hydrophilic volatiles was significantly greater (p<0.05) in high IMF grilled beef, consistent with more intense sensory flavor. Faster oral breakdown and higher peak saliva concentrations of non-volatile flavor compounds in high IMF grilled beef were consistent with higher tenderness and more intense flavor perception.

Relative bioavailability of 13C5-folic acid in pectin-coated folate fortified rice in humans using stable isotope techniques

Background/Objectives:The aim of the study was to measure the relative bioavailability of labeled pteroylglutamic acid (13C5-PteGlu) from a pectin-coated fortified rice in vivo to measure any effect of the edible coating on folic acid bioavailability.Subjects/Methods:Healthy volunteers (N=26) aged 18–39 years received three test meals in three randomized short-term cross-over trials: Trial 1: aqueous 400 μg 13C5-PteGlu, Trial 2: 200 g cooked white rice+400 μg 13C5-PteGlu,Trial 3: 200 g fortified cooked white rice with pectin-coated premix containing 400 μg 13C5-PteGlu. Blood samples were drawn at 0,1,2,5 and 8 h postprandial. The concentration of 13C5-5 methyl-tetrahydrofolate appearing in plasma was quantified using high performance liquid chromatography–mass spectrometry (MS)/MS. For 24 h before baseline estimation and during the area under the curve (AUC) study, the subjects were placed on a low folate diet (∼100 μg/day). The relative bioavailability of the folic acid following Trial 3 was measured by comparing the 13C5-5 methyl-tetrahydrofuran (THF) AUC with Trials 1 and 2.Results:The bioavailability of folic acid in a pectin-coated rice premix was 68.7% (range 47–105) and 86.5% (range 65–115) in uncoated fortified rice relative to aqueous folic acid.Conclusion:This study is the first demonstration of the bioavailability of folate in pectin-coated fortified rice in humans.

Micronutrients Fortification of Rice by Parboiling: Lab Scale and PilotScale Studies

Deficiency diseases due to micronutrient insufficiency occur worldwide, especially in developing countries. Folic acid deficiency causes neural tube defects (NTD) and affects the central nervous system in 1:1000 births leading to anencephaly and spina bifida. Anaemia, a public health problem is caused by iron deficiency in 50% of the cases. Sub-clinical Vitamin A deficiency (VAD) causes morbidity and mortality, especially among young children and pregnant women. In young children, it can cause xerophthalmia and keratomalacia and lead to blindness or limited growth and weakening of the immune system, thereby increasing the risk of death. This study investigates the efficiency of using parboiling as a processing technique to fortify rice with folic acid, β-carotene and iron. Brown rice was parboiled by soaking with the micronutrients at the optimum conditions (70°C for 2 hours), steaming the soaked rice at 100°C for 1 hour and air drying until the moisture dropped to 10 ± 2% wb. Retention of these nutrients was assessed by analysis in the dried rice after milling (0 s, 60 s and 120 s) and in the cooked rice. The fortification was scaled up using 2.5 kg rice by parboiling with the highest concentration of the micronutrient mixture. The experimental process was compared with the conventional parboiling process for which the retention of the micronutrients was analysed. Retention of the nutrients in rice reduced during milling and cooking decreased by 10-15% (folic acid); 2-8% (β-carotene) and 4-5% (iron). Fortification of rice using parboiling is feasible. The laboratory scale method correlated well with the pilot scale.

SOLVENT STRUCTURE AND THE INFLUENCE OF ANIONS ON THE GELATION OF K-CARRAGEENAN AND ITS SYNERGISTIC INTERACTION WITH LOCUST BEAN GUM

1 ABSTRACT The synergistic interaction of K-carrageenan with locust bean gum has been studied in the presence of potassium chloride, nitrate, acetate, sulphate, citrate and EDTA. Gelation of K-carrageenan alone was only weakly dependent on the nature of the anion but the rupture strength (RS) of the mixed gel was more strongly influenced by different anions. RS increased linearly with the viscosity B-coefficient, a measure of the structure-making (or structure-breaking) effect of the anion. This suggests that anions that best promote structure in the surrounding water molecules are most effective in stabilising the junction zones in the mixed gel network.

Systematic error in the calculated specific acid production rate in anaerobic fermentation of Lactococcus lactis in the presence of carbon dioxide

The lactococci are commonly grown anaerobically, blanketed with a mixture of nitrogen and carbon dioxide. Specific acid production rate is often determined by alkali usage in constant pH fermentations. The combination of these methods leads to incorrect acid production figures because the added carbon dioxide reacts with some of the alkali.