Enzymatic Extraction and Modification, and Frying Stability of Moringa Oleifera Seed Oil.

Consumption of edible oils has grown with the increase in world population. The increasing health awareness and consciousness amongst consumers made the food industry more discriminating in the types of oil they use for food applications. Many circumstances have focused attention on high-oleic vegetable oils, which have been demonstrated to reduce the risk of coronary heart disease. The demand for high-oleic oils is increasing but there are only a few known sources available. Moringa oleifera seed oil, which is naturally high-oleic oil, therefore, presents a great opportunity for the oil industry for meeting this ever-increasing demand. The objectives of this study were to determine the properties of oil extracted from Moringa oleifera seeds, evaluate the efficiency of enzymatic-extraction of the oil and modification of the oil to enhance its oleic acid content and compare the oxidative stability of the oil against several other oils during deep fat frying.The oil content of M. oleifera seeds in Malaysia ranged between 30.8% and 33.4% depending on the variety, of which there were two. The physico-chemical properties of the oil were determined following extraction with light petroleum ether. The dominant fatty acid (FA) of the oil was indeed oleic acid, where Variety 1 contained 67.9% while Variety 2 contained 74.4%. After refining, the oil from both varieties is light golden color (O.1R + 1 .OY), and a viscosity, smoke point and refractive index (nD400C) of Cp 51.7, 206"C, and 1.4533, respectively. Using electronic nose analysis, the crude oil was found to have an odor similar to that of peanut oil. It has a complete melting point of 18.9"C. The crude oil contains 95.6% triacylglycerols (TAG) and 1.9% 1,2- and 1,3- diacylglycerols. The relative TAG content increased to 98.7% after refining. The oil contains 36.7% trioleoyl glycerol (000) as the main TAG. M. oleifera seed oil was extracted using four different types of enzymes namely; Neutrase 0.8L (neutral protease), Termamyl 120L, type L (a-amylase), Pectinex Ultra SP-L (pectinase) and Celluclast 1.5L FG (cellulase) all supplied by Novozymes (Bagsvaerd Denmark). The enzymes were used either separately or in combination. The efficiency of enzyme-extraction was compared to aqueous extraction without enzyme. Enzymatic-extraction of M. oleifera seed oil showed that Neutrase alone at 2% vlw, 45°C and pH 6.8 was able to extract 71.9% oil relative to the amount obtained when the oil was solvent-extracted. Neutrase was the most efficient among the enzymes used followed by Termamyl, Celluclast and Pectinex with percent oil recoveries of 64.8%, 62.6% and 56.5%, respectively. Each extraction was carried out at the optimum pH and temperature of the enzymes. A combination of the four enzymes at pH 7.5 increased the oil recovery to 74%. Percent oil recovery with all enzymes was significantly (P<0.05) higher than the control (aqueous extraction without enzyme) (3 5.6%). Solvent extracted M oleifera seed oil was transesterified using immobilized lipase (Lipozyme IM 60) (Novozyrnes Bagsvaerd Denmark) in order to change its melting and crystallizing behavior that will make it easier to fractionate. After transesterification, the oil was fractionated with acetone at -18°C and without acetone at 10°C to obtain two fractions, stearin and olein fractions. Incubation of the transesterified oil at 10°C for 24 h resulted in the formation of fat crystals, which settled at the bottom of the flask in sample transesterified for 24 h, while the control (0 h) sample became rather viscous with fat crystals in suspension. Transesterification affect the TAG profile of the oil, which in turn affected the solid fat content (SFC) and thermal behavior. The SFC value at 0°C after 24 h of reaction was 10.35% and significantly (P<0.05) higher than the control (0 h) (7.94%). The oil remained liquid at 20°C for all reaction times. The end set temperature (melting point) shifted from 18.9"C for the unreacted oil to 20S°C for oil transesterified for 24 h. Transesterification of the oil resulted also in a significant (P<0.05) increase in the crystallization temperature of the high melting glyceride from the original value of 1.6"C to 12.9"C after transesterification for 24 h. There was a significant increase in the oleic acid content in the olein fractions obtained following fractionation of the transesterified oil with and without using acetone (75.2 and 70.5%, respectively) compared to the unreacted oil (67.9%).The oxidative stability of refined M oleifera seed oil (MOO) in deep fat frying was evaluated and compared with canola (CLO), soybean (SBO), and palm olein (PO). The oils were used to fry potato chips for 6 h a day up to a maximum of 5 days. Changes in fatty acid (FA) composition, free fatty acids (FFA), iodine value (IV) peroxide value (PV), p-anisidine value (p-AV), specific extincti o;:1~n( 233 and 269 nm for conjugated dienes and trienes), total polar compounds (TPC), color and viscosities were used to evaluate the oils. The frying process caused an increase in the FFA contents MOO, PO, CLO and SBO. The FFA contents at the end of the frying period were 0.35%, 0.55%, 0.54% and 0.51% for CLO, PO, SBO and MOO, respectively. The rate of increase in the PV (meqOz/kg) for CLO (2.33 per day) was higher compared to those of MOO (0.80 per day), PO (1.00 per day), and SBO (0.70 per day). Conjugated dienes levels at the end of the frying period were lowest in PO (4.27) followed by MOO (6.07) with high levels in CLO (9.28) and SBO (10.64). The amount of TPC in MOO (20.78%) and PO (21.23%) were significantly (P<0.05) lower than those in CLO (28.73%) and SBO (3 1.82%). Color and viscosity of the oils increased with frying time. The rates of change of viscosity with the frying days were similar for all the oils. Results of sensory analysis conducted on potato chips fried in PO and MOO showed general acceptability of potato chips fried in both oils with high scores for crispness (7.07 and 7.14), oiliness (6.86 and 7.09), and fried food flavor (7.00 and 6.79) attributes, respectively. The overall acceptance of the French fries fried in MOO was high (7.50) and not significantly (P>0.05) from that of PO (7.58)

Fatty acid ratios and their relative amounts as indicators of oil stability and extent of oil deterioration during frying.

Palm olein (PO), canola (CLO), soybean (SBO) and Moringa oleifera seed oils (MoO) were used to fry potato chips for 6 h a day for 5 days and extent of deterioration determined. FA ratios C 18:1/ C 18:2 + C 18:3 and amounts of C 18:1 + C 16:0 were compared to changes in total polar compounds. TPC in MoO (20.78%) and PO (21.23%) were significantly lower than those in CLO (28.73%) and SBO (31.82%). There was a decrease in the amounts of C 18:2 from day 0 to 5 in PO (10.80 to 8.37%), CLO (22.76 to 19.92%) and SBO (53.00 to 51.57%) and a decrease in C 18:3 in CLO (6.77 to 4.55%), respectively, and an increase in C 16:0; MoO (6.10 to 9.60%) and PO (37.70 to 41.99) and a decrease in C 18:1; (74.40 to 73.03%) in MoO, respectively. There was a negative correlation (r = - 0.9919) between C 18:1/ C 18:2 + C 18:3 and TPC produced in PO, CLO and SBO

Comparison of melting behaviors of edible oils using conventional and hyper differential scanning calorimetric scan rates

HyperDSC™ (fast scan rate) was used to study the melting behavior of canola (CLO), sunflower (SFO), palm olein (PO), rice bran oils (RBO), and cocoa butter (CB), and was compared to the melting behaviors using conventional DSC. There was an increase in sensitivity with increase in scan rate. Slow scan rate (5 to 20C/min) gave low sensitivity, which increased when the scan rates were increased to 50, 100 and 200C/min. Peak resolution was affected by scan rate depending on the sample weight. Increase in the size of sample coupled with the use of fast scan rate decreased the peak resolution. Generally small sample sizes gave better peak resolution. Results of the effect of scan rate on glass transition (Tg) shows that Tg, which is a weak transition especially in crystalline and low amorphous materials was not detected using conventional scan rates (5 to 20oC/min). It was however detected using of hyperDSC™ scan rates (100 to 200oC/min). Increasing the scan rate resulted in an increase in the peak temperature and the elimination of shoulder peaks, which were caused due to the polymorphic behavior of the triacylglycerols in the oils. The increase in peak temperature caused a shift in the peak position towards a higher temperature value. There is a positive correlation between the peak temperature and scan rate. The correlation coefficients (r) for CLO, SFO, PO, RBO and CB were 0.96, 0.95, 0.97, 0.96 and 0.96 respectively

Thermophysical properties of some species of Malaysian freshwater fish in unfrozen state

Five widely consumed species of freshwater fish in Malaysia were investigated to determine their thermophysical properties due to their handling need for food industry sector from the viewpoint of the heat transfer calculations. These properties encompassed thermal conductivity, specific heat and thermal diffusivity. The species under study were black tilapia, red tilapia, catfish, yellowtail catfish and red pomphret. The major components (moisture, fat, protein, carbohydrate and ash contents) of the fish muscle were determined for each species in a fresh state. Mathematical formulae, which correlate between the components’ values and the thermophysical properties were used to calculate these properties and their variation with temperature. The results were compared with the existing literature of other fish. Slight differences were noticed, however, the results were still within the common range of fish thermophysical values. The differences may be attributed to the different cultural and growing conditions. A logistic model correlated between the thermal diffusivity and temperature variation was developed in this work. It represents the basic requirement to the solution of heat transfer equation by which the thermal processing problems could be solved

Determination of types of fat ingredient in some commercial biscuit formulations

A study was carried out to compare the composition and thermal profiles of the fat component of six brands of commercial biscuits (BA, BB, BC, BD, BE & BF) with those of lard and palm oil. Extraction of fat from biscuit samples was done using petroleum ether according to the soxhlet extraction procedure. The isolated fat samples along with lard and palm oil were analyzed using gas liquid chromatography (GLC), reversed-phase high performance liquid chromatography (RP-HPLC), and differential scanning calorimetry (DSC). According to GLC analysis, palm oil, lard and all six biscuit brands had either palmitic or oleic acid as major fatty acids. Sn-2 positional analysis of fatty acids showed that oleic (> 60%) as the most dominant fatty acid of palm oil and biscuit brands BA, BB, BC, and BD while palmitic (> 60%) as the most dominant fatty acid of lard and biscuit brands BE and BF. RP-HPLC analysis showed that the triacylglycerol (TAG) profiles of lard and biscuit brands BE and BF were closely similar while those of brands BA, BB, BC, and BD and palm oil were similar. DSC analysis showed that the cooling and heating profiles of lard and brands BE and BF were similar, while those of palm oil and brands BA, BB, BC, and BD were similar. Hence, this study concluded that biscuit brands BE and BF are not suitable for consumers whose religious restriction prohibit the use of lard as food ingredient

Effects of germination conditions on 5’-phosphodiesterase activity of selected seeds

5'-Phosphodiesterase (5'-PDE) is an enzyme that hydrolyses RNA to form 5'-inosine monophosphate (5'-IMP) and 5'-guanosine monophosphate (5'-GMP), which function as flavour enhancers. Selection of the best producer of 5'-PDE was made by determining the activity of the enzyme in six seeds that have been germinated, namely mung bean (Vigna radiate), soybean (Glycine max), adzuki/red bean (Vigna angularis L.), chick pea (Cicer arietinum), black eye pea (Vigna unguiculata) and petai (Parkia speciosa). Seeds that were not germinated acted as the control. In order to ensure there is no contamination from potential 5'-PDE-producing microorganisms during germination, microbial growth was reduced by using different surface sterilizing treatments where the seeds were soaked in 100 mL solution containing different concentrations of sodium hypochlorite (with or without 0.05% sodium azide) for 5 minutes before rinsing it five times with sterilized distilled water (total 500 mL).The seeds were observed every day for 3 days and the best surface sterilizing treatment was selected based on absence of mold growth and the effects on hypocotyl length. Sodium hypochlorite at 0.3% (v/v) concentration was able to inhibit mold growth in adzuki bean, soybean and chickpea. On the other hand, only 0.1% (v/v) sodium hypochlorite was needed to inhibit mold growth in black eye pea and petai, while mung bean required 0.05% (v/v) sodium hypochlorite to inhibit mold growth. Under these conditions, the growth of hypocotyl (hypocotyls length) was only slightly affected compared to the control. 5'-PDE was extracted from seeds that have been germinated for 24 hours and their control (ungerminated seeds) by homogenization in a blender with 400 mL of 50 mM acetate buffer, pH 4.5. After that, the homogenates were stirred for 30 min and the centrifuged at 9000 rpm for 15 min at 10°C. 5'-PDE activity was determined using thymidine 5'-monophosphate p-nitrophenyl ester as substrate at pH 7.0 and 55°C. The formation of nucleotide monophosphates, the products of reaction, was determined at 405 nm. As a strong presence of phosphomonoesterase (PME) will reduce the yield of nucleotide monophosphates as the enzyme hydrolyzes these products into nucleosides and orthophosphate, PME activity was also determined using p-nitrophenyl phosphate as the substrate at 60°C and pH 5.0. Thus, the seed with the highest 5'-PDE activity and a low PME activity can be selected. Germinated adzuki bean was found to have the highest 5'-PDE activity (0.59 μmol p-nitrophenol/min/mg protein) among the germinated seeds. A time-course study indicated that the level of 5'-PDE in adzuki bean increased with time of germination until 15 hours (0.69 μmol p-nitrophenol/min/mg protein), after which the acitivity decreased until it reached the basal level (0.44 μmol p-nitrophenol/min/mg protein) at 72 hours. On the other hand, PME in the bean was the highest at 9 h germination(0.98 μmol p-nitrophenol/min/mg protein). In general, controls have very low basal level of 5'-PDE activity (0.18-0.42 μmol p-nitrophenol/min/mg protein)

Effect of salt concentrations on the growth of heat-stressed and unstressed Escherichia coli

The effect sodium chloride (NaCl) and potassium chloride (KCl) concentration on the growth of Escherichia coli cells cultivated at 37 and 44°C was studied in an effort to understand the importance of the salts and glucose in medium to the growth of E. coli. A turbidimetric method was used to measure the growth of E. coli after a 24 hours incubation period. The turbidimetric method used gave a high correlation (R2 = 0.9606) with the traditional surface colony count method. Four sets of salt concentrations, 0, 0.5, 1.0 and 1.5% (w/v), were employed throughout this study. Absence of NaCl in the medium was found to slightly decrease the growth of E. coli at 37°C. E. coli grew optimally at 0.5% (w/v) NaCl concentration. Addition of 0.5% KCl was found to have less beneficial effect on the growth of E. coli at 37°C compared to cells grown in medium with 0.5% NaCl. Increase in the concentrations of both salts above 0.5% decreased growth at 37°C. The extent to which growth was suppressed was directly proportional to the concentration of salts. At zero concentration of both salts, growth of E. coli was very low at 44°C. Increase in the concentrations of both NaCl and KCl from 0.5% to 1.5% resulted in growth enhancement. Glucose affected significantly the growth of E. coli at 37°C. Addition of 140 mM (w/ v) of glucose to the medium increased the growth of E. coli at 37°C to a greater extent than was obtained by salt addition. However, the addition of the same concentration of glucose was found to have only a very slight effect on growth at 44°C

Improvement of glucose production by raw starch degrading enzyme utilizing acid-treated sago starch as substrate

The native sago starch exists as a compact crystalline structure and is not efficiently hydrolyzed by Raw Starch Degrading Enzyme (RSDE). In order to enhance its hydrolysability, the starch was treated with acid and heated below its gelatinization temperature, thus increasing the accessibility of the sago starch granule to enzymatic attack. Results showed that treatment of sago starch with acid at pH 2.0 and temperature 65oC for 2 hours greatly enhanced its conversion rate to glucose from 53.3% to 71.9%. It is clearly shown that high yield of glucose is produced during hydrolysis of acid-treated sago starch using the Raw Starch Degrading Enzyme from Acremonium sp. The difference between the acid-treated and untreated sago starch in this study could be due to the differences on the surface of the sago starch granule which may influence the accessibility and diffusion of enzyme into the starch during hydrolysis

Sensory and physicochemical qualities of palm olein and sesame seed oil blends during frying of banana chips.

Palm olein and sesame seed oil were blended at varying ratios; changes in their physicochemical and sensory characteristics were determined. Increasing amounts of SSO (from 10 to 20, 30 and 40%) and decreasing amounts of PO (from 90, 80, 70 and 60%) in the blends, results in increase in the degree of unsaturation. FFA increased from 0.25% (90 PO: 10 SSO) to 0.65%. (60 PO: 40 SSO). Blending altered FA composition of palmitic and linoleic acids, which results in a significant change in trilinolein, dioleoyl-linoleoyl-glycerol, dipalmitoyl-3-linoleoyl glycerol and dipalmitoyl-3-oleoyl glycerol contents. A pleasant nutty flavor was imparted. Melting and crystallization temperatures shifted to lower values from 12.65 to 11.03, 10.44 and 9.74ºC and from -6.31 to -6.99, -7.38 and -8.31 ºC, respectively. Sensory quality of banana chips fried in the oil blends showed no acceptability differences between them. All blends received high scores for all sensory attributes tested and overall acceptability

Determinar de la estabilidad oxidativa y la calidad del aceite de chufa (Cyperus esculentus) y su actividad antioxidante durante el calentamiento por microondas

Introduction: The emphasis on high-oleic vegetable oils is prominent in human communities all over the world. That being said, the high level of monounsaturated fatty acid (oleic acid) in tiger nut (Cyperus esculentus) oil shows that it is resistant to oxidative stability. The purpose of this study, therefore, was to see if tiger nut oil can be exploited for use as an alternative or supplementary source of high-quality and nutritious cooking oil. Materials and methods: In this study, Color, RI, viscosity, PV, p-AV, FFA, TPC, at 233 and 269 nm, thermal behavior, TAG and FAC were used to evaluate the oil after microwave heating. Results: The PV, p-AV, FFA, TPC and specific extinction were increased during the microwave heating. Significant differences (p &lt; 0.05) were detected for peroxide, anisidine, acid value, polar compounds and specific extinction. During microwave heating, the amounts of peroxide, anisidine and TOTOX values increased from initial value 3.06, 0.72 and 6.84 for unheated oil to 4.11, 10.02 and 18.25 after 15 min heating respectively. Free fatty acid changed from 0.10 to 0.12% during microwave heating. Amount of unsaturated fatty acids decreased during the heating significantly. During microwave heating the antioxidant activity was significantly decreased (p&lt;0.05) from 68.60 to 19.66 (for unheated tiger nut oil and after 15 min heating in high concentrations by DPPH test, respectively). Conclusions: This may indicate that it can bear thermal treatments in such culinary methods as frying, and it can thus be concluded that tiger nut oil is stable in heating processes, especially frying.Introducción: El énfasis en los aceites vegetales con alto contenido de ácido oleico es prominente en las comunidades humanas de todo el mundo. Dicho esto, el alto nivel de este ácido graso monoinsaturado (ácido oleico) en el aceite de chufa (Cyperus esculentus) muestra que es resistente a la estabilidad oxidativa. El propósito de este estudio fue ver si el aceite de chufa puede explotarse para su uso como una fuente alternativa o suplementaria de aceite de cocina de alta calidad y nutritivo.Materiales y métodos: En este estudio se utilizó el Color, RI, viscosidad, PV, p-AV, FFA, TPC, a 233 y 269 nm, comportamiento térmico, TAG y FAC para evaluar el aceite después del calentamiento por microondas.Resultados: El PV, p-AV, FFA, TPC y extinción específica aumentaron durante el calentamiento con microondas. Se detectaron diferencias significativas (p &lt;0,05) para el peróxido, la anisidina, el valor del ácido, los compuestos polares y la extinción específica. Durante el calentamiento con microondas, las cantidades de los valores de peróxido, anisidina y TOTOX aumentaron desde el valor inicial de 3,06, 0,72 y 6,84 para el aceite no calentado a 4,11, 10,02 y 18,25 después de 15 minutos de calentamiento respectivamente. El ácido graso libre cambió de 0,10 a 0,12% durante el calentamiento con microondas. La cantidad de ácidos grasos insaturados disminuyó significativamente durante el calentamiento. Durante el calentamiento con microondas, la actividad antioxidante disminuyó significativamente (p &lt;0,05) de 68,60 a 19,66 (para el aceite de chufa sin calentar y después de 15 minutos de calentamiento en altas concentraciones mediante la prueba de DPPH, respectivamente).Conclusiones: Esto puede indicar que el aceite de chufa puede soportar tratamientos térmicos en métodos culinarios como la fritura y se puede concluir que el aceite de chufa es estable en los procesos de calentamiento, especialmente la fritura