RANCIDITY OF WALNUTS AND ALMONDS AFFECTED BY SHORT TIME HEAT TREATMENTS FOR INSECT CONTROL

Short time heat treatments effectively control insect contamination of nuts containing substantial quantities of polyunsaturated fatty acids susceptible to oxidative rancidity. Walnut kernels contain greater concentrations of polyunsaturated fatty acids than almond kernels. The objectives of this research were to investigate the lipid stability of shelled walnuts and almonds as affected by short time heat treatments and accelerated storage temperatures. Heating treatments were at 55C for 2 min, 55C for 10 min, 60C for 2 min or 60C for 10 min to simulate predetermined deinfestation treatments. Untreated control and heat treated shelled walnut and almond kernels were stored at 25C for 5, 15, 30 and 60 days or 35C for 2, 5, 10 and 20 days to simulate the shelf lives of walnut and almond kernels at 4C for 2 years. Oils extracted from untreated and short time heat treated walnut kernels exhibited higher peroxide values than oils extracted from untreated and short time heat treated almond kernels under equivalent conditions. Oils extracted from untreated walnut kernels exhibited significantly (P ± 0.05) higher peroxide values than oils extracted from short time heat treated walnut kernels after 5, 15, 30, and 60 days of storage at 25C, or after 2, 5, 10, or 20 days of storage at 35C. Oils extracted from untreated almond kernels exhibited higher peroxide values than oils extracted from short time heat treated almond kernels after 5, 15, 30, or 60 days of storage at 25C, or after 2, 5, 10 or 20 days of storage at 35C. Oils extracted from untreated walnut kernels and oils extracted from short time heat treated walnut kernels exhibited higher peroxide values than oils extracted from almond kernels after storage at 25C or 35C. Short time heat treatment does not enhance development of rancidity during accelerated storage of walnut or almond kernels.     

Temporal aggregation and spurious instantaneous causality in multiple time series models

Large aggregation interval asymptotics are used to investigate the relation between Granger causality in disaggregated vector autoregressions (VARs) and associated contemporaneous correlation among innovations of the aggregated system. One of our main contributions is that we outline various conditions under which the informational content of error covariance matrices yields insight into the causal structure of the VAR. Monte Carlo results suggest that our asymptotic findings are applicable even when the aggregation interval is small, as long as the time series are not characterized by high levels of persistence.     

Improvements in seismic event locations in a deep western U.S. coal mine using tomographic velocity models and an evolutionary search algorithm

Methods of improving seismic event locations were investigated as part of a research study aimed at reducing ground control safety hazards. Seismic event waveforms collected with a 23-station three-dimensional sensor array during longwall coal mining provide the data set used in the analyses. A spatially variable seismic velocity model is constructed using seismic event sources in a passive tomographic method. The resulting three-dimensional velocity model is used to relocate seismic event positions. An evolutionary optimization algorithm is implemented and used in both the velocity model development and in seeking improved event location solutions. Results obtained using the different velocity models are compared. The combination of the tomographic velocity model development and evolutionary search algorithm provides improvement to the event locations.     

Vitamin C Retention of Potato Fries Blanched in Water

Vitamin C retention was determined microfluorometrically for French fries heated in water. Vitamin C retention for 1.3 cm (½ in.) water blanched French fries ranged from 83.2–54.1%. The French fry blanch times were 5, 10 and 15 min at 66°C, 77°C and 88°C. The apparent Ea was 4.0 Kcal/mole.     

EFFECT OF A CARBOHYDRATE-BASED FAT SUBSTITUTE AND EMULSIFYING AGENTS ON REDUCED-FAT PEANUT BUTTER COOKIES

Oatrim replaced 75 and 100% of the butter in peanut butter cookies. Emulsifiers [diacetyl-tartaric esters of monoglycerides (DATEM) and sodium stearoyl-lactylate (SSL)] -were incorporated (0.0, 0.1 and 0.2% formula-weight-basis) in combination with oatrim. Data were analyzed with PROC MIXED and contrast statements. Water activity increased as oatrim increased. Oatrim increased Color L. Cookie spread was reduced; cookies with 75% butter replacement with oatrim and 0% emulsifier equaled the control. Oatrim decreased hardness and brittleness; 0.1% SSL moderated the brittleness decrease but resulted in a hard cookie. Cookies with 75% oatrim most closely matched the control; fat Kcal decreased 36%.     

INACTIVATION of SACCHAROMYCES CEREVISIAE IN APPLE JUICE BY SQUARE-WAVE and EXPONENTIAL-DECAY PULSED ELECTRIC FIELDS

With equivalent electrical energy input, inactivation of microorganisms by pulsed electric fields depends on pulse waveform. Exponential-decay and square-wave pulsed electric fields were selected to treat Saccharomyces cerevisiae suspended in apple juice. A parallel-plate static treatment chamber with 25 ml volume and 0.95 cm electrode gap was used. Peak electric field and pulse electric energy input were 12 kV/cm and 260 Joules per pulse for both waveforms. Both waveforms were found effective in the microbial inactivation. However, inactivation of S. cerevisiae treated with square-wave pulses was greater than yeast treated with exponential-decay pulses. For the purpose of food pasteurization, square-wave pulsed electric fields may result in significant energy savings compared to exponential-decay pulses.     

HIGH HYDROSTATIC PRESSURE PROCESSING OF PEACH PUREE WITH AND WITHOUT ANTIBROWNING AGENTS

High hydrostatic pressure (HHP) (103 to 517 MPa) was applied for selected times (5 to 25 min) on peach puree with and without the addition of antibrowning agents (1000 ppm ascorbic acid or 300 ppm cysteine). Polyphenoloxidase (PPO) activity was assessed before and after HHP processing. Peach purees were stored at 3C for 13 days and then at 22C for 15 additional days. A z_p value of 224 MPa, in a range from 207 to 517 MPa of pressure, was obtained for peach puree without the addition of antibrowning agents. PPO activation at 103, 207 and 310 MPa or inhibition at 414 and 517 MPa was observed in peach purees containing added ascorbic acid. More than 50% inactivation of PPO was observed after adding cysteine to the peach puree and 99% inhibition was observed after 517 MPa of pressure at the experimental times. The higher the pressure treatment and the longer the treatment time for inactivating PPO, the less the discoloration of the peach puree with and without antibrowning agents during storage at low temperatures.     

Analysis and Thermal Stability of Porcine Thyroglobulin-Binding Lectins in the Major Phaseolus vugaris L. G2/Albumin Groups

Porcine thyroglobulin (PTG)-binding lectins from cultivars representing the five major G2/albumin groups of Phaseolus vulgaris L. were quantified and assayed for thermal stability with PTG-Sepharose affinity chromatography and the Folin-Ciocalteau protein assay. Lectin concentrations of the five cultivars were 30, 25, 21, 21 and 15 mg g^?1 dry flour, for Jamapa (M_G2), ICA-Pijao (B_G2), California Light Red Kidney (T_G2), Black Turtle Soup (V_G2) and Sanilac (S_G2), respectively. Heat stabilities of the five major lectin-containing G2/ albumin groups were M_G2= B_G2G2G3G2. Thermally processing whole beans at 89°C for 60-130 min inactivated the lectins in all G2/albumin groups.