Search

A short publication about the proper procedures for freezing fruits and vegetables.

Rationale: Published studies have shown that immigrants undergo dietary acculturation which may have positive or negative impact on their health. Therefore, a study was conducted to investigate this critical issue of dietary acculturation and any possible influence on the health status of newly arrived international students at Virginia Tech in Fall 2010. Design: In this study weight, fasting blood glucose and blood pressure of 35 international students (age 18-36 years) were determined at three time points, 5-6 weeks apart. Participants filled out a 20-item-questionnaire addressing alteration in the native and American dietary habits. Furthermore, 24 hrs dietary recalls and frequency of consuming the most popular food items in the US was assessed. Results: Total sample population (TSP) had a significant increase in average weight by 2.79 lbs from visit 1 (V1) to visit 3 (V3) (p=0.0082), Participants who gained weight (PGW; n=10) had an average increase by 9 lbs. Country wise, Chinese had a statistically significant average increase in their weights by 4.16 lbs (p=0.0077) whereas, Indians and Germans had an average increase by 2.36 lbs and 1.28 lbs respectively. Gender wise, the average increase in weight for females was 3.99 lbs (p=0.0015) while for males 1.52 lbs from V1 to V3. There were no significant differences in total caloric consumption from V1 to V3 for both groups of international students. There were no significant changes in the fasting blood glucose and systolic blood pressure from V1 to V3. There was an increase in frequency of consuming high calorie American food items in V3 when compared with V1. Frequency of burger consumption was highly increased in the TSP group while bagels were significantly increased in PGW group. There was an overall increasing trend towards American diet, cooking and eating habits. Finally, we conclude that the international students are gradually acculturating to the American diet and have impact on their weight which may potentially have a negative impact on their health status. Future studies and orientation program catered to the needs of adjusting to acculturation process of international students are recommended. Master of Science

The incidence of type 2 diabetes is considered an epidemic in Western countries, and its prevalence is more common in the Hispanic population than in non-Hispanic whites. Postprandial hyperglycemia has been associated with oxidative stress (OS), thus; reducing postprandial glycemia and/or OS through dietary consumption of resistant starch (RS) may be one approach to help modulate glucose and insulin responses. The purpose of this study was twofold: 1) to evaluate the physicochemical and sensory properties of cereal food products supplemented with RS. 2) to compare the effects of a single ingestion of granola bars with high (~18 grams of RS) and low (~0 grams of RS) RS compositions on the postprandial glucose and insulin responses (n=14) and oxidative stress parameters (cellular glutathione peroxidase, F2- isoprostanes, and oxygen radical absorbance capacity) in Hispanic women (n=9). Granola bars and cereals were developed to provide 2 levels (10% and 15%) of RS; isocaloric (0% RS) control samples were prepared with readily digestible (high amylopectin) starch. Samples were stored for up to 4 weeks at 20 °C. Mean composition of the high RS granola bars was 6% protein, 15% moisture, and 18% lipid. RS levels slightly increased from 14 to 16 g/serving after 4 weeks of storage, supporting published research that RS increases with storage due to retrogradation and crystallization of amylose chains. Color became lighter as the level of RS increased (p

Soy peroxidase enzyme obtained from isoelectic precipitation procedures was added to all-purpose flour (APF) to assess its effects on the rheological properties and consumer acceptability of yeast bread. A pH 4.8 isoelectrically precipitated fraction from soybeans was used because it produced the most precipitate and had about the same peroxidase activity as the other fractions. Gluten strength was determined using a farinograph for seven treatment groups: control (all-purpose flour), bread flour, all-purpose flour + soy flour, bread flour + soy flour, all purpose flour + pH 4.8 precipitate, all-purpose flour + 15 mg soybean peroxidase, and all-purpose flour + 25 mg soybean peroxidase. Four types of yeast bread were baked for loaf volume determination, texture analysis, and consumer acceptability: a control loaf using only all-purpose flour, a reference loaf using all bread flour, a loaf with all purpose flour + whole soy flour, and a loaf with all-purpose flour + pH 4.8 soy precipitate. The APF+soy flour, bread flour, bread flour + soy flour, and the APF + pH 4.8 precipitate produced an improvement in the gluten strength and mixing tolerance compared to the control (p

The goal of this research is to determine the effects of added soybean lipoxygenase (LOX) on bread dough rheological properties and physical properties of bread loaves compared to controls, and to determine sensory attributes of bread loaves using quantitative descriptive analysis (QDA). Protein fractions were obtained through the use of isoelectric precipitation. The pH 4.8 precipitate was found to yield the greatest LOX activity when compared with other fractions (p

Background: African-Americans are a vulnerable population group with disproportionately elevated rates of type 2 Diabetes Mellitus (DM). Resistant starch is a promising food ingredient that has the potential to reduce the risk factors involved in the development of type 2 DM. To date, there is a dearth of published research studies on the effect of resistant starch on African-Americans who are at increased risk for type 2 DM. Objective: The major objective of this study was to determine if daily consumption of approximately twelve grams of high-maize™ 260 resistant starch (RS) added to bread improved glucose homeostasis by monitoring changes in fasting plasma glucose, fructosamine, hemoglobin A1c, insulin, glucagon-like peptide-1, C-reactive protein, homeostasis model assessment insulin resistant (HOMA- IR) and beta-cell function (HOMA-Beta), serum acetate, propionate, and butyrate levels. Design: A fourteen-week, randomized, double-blind, within-subject crossover design feeding study was carried out in African-American males (n=8) and females (n=7) at increased risk for type 2 DM who resided in Southwest Virginia. All participants consumed bread containing added RS or control bread (no added RS) for six-weeks. RS and control bread feedings were separated by a two-week washout period. Results: Fasting Plasma Glucose (FPG) levels were significantly lower (P = 0.0179) after six-week control bread feedings compared to baseline. FPG levels were also significantly lower (P < 0.0001) after two-week washout period than at baseline. FPG levels were significantly higher (P < 0.0001) after six-week resistant starch bread feeding than at washout. FPG levels due to consumption of resistant starch versus control bread approached significance (P = 0.0574). Fructosamine levels were significantly lower (P = 0.0054) after control bread and resistant starch bread (P < 0.0012) consumption compared to baseline. No significant differences were found in fructosamine levels due to resistant bread intake versus control (P = 0.9692). Mean baseline HbA1c levels were 6.9% (n=15). This value was slightly lowered to 6.79% (n=14) at the end of the fourteen-week study, although statistical significance was not found. Mean ± standard errors for HbA1c values were 6.9% ± 0.18% and 6.9% ± 0.14% at baseline for the sequence groups, resistant starch first (n=7) and control treatment first (n=8) groups, respectively. Mean± standard error HbA1c values were 6.7%± 0.27% and 6.9% ± 0.27% at the conclusion of fourteen-week study for sequence groups, resistant starch first group (n=7) and control treatment first group, respectively. Baseline mean and standard errors C-reactive Protein (CRP) levels for male and female combined results were 0.62 ± 0.16 mg/dL (n=15). Mean CRP levels were 0.53 ± 0.12 mg/dL for resistant starch bread and 0.64 ± 0.21 mg/dL for control bread feeding periods. No significant differences were found for treatment, gender, or sequence effects for C-reactive protein levels during the fourteen-week study (P > 0.05). Mean HOMA-IR levels following six-week resistant starch and control bread consumption decreased to normal values (> 2.5), although no significant differences were found for treatment (P = 0.5923). Conclusions: Eighty-seven grams of Hi- maize™ 260 Resistant Starch added to baked loaves of bread consumed by a free-living African-American population at increased risk for type 2 diabetes did not consistently show significance in all clinical indicators and biochemical markers assessed. On the basis of the evidence in this study we do not have evidence that this amount of resistant starch in this population's diet will prevent the onset of diabetes. However, results are suggestive that higher levels of resistant starch in a more controlled experiment could reduce clinical risk factors for type 2 diabetes. Ph. D.

This study examined the effects of guar gum and xanthan gum on flax supplemented breads through objective and sensory testing. Breads containing flaxseed and gums were found to have a significantly (p0.05) difference in peroxide values among bread samples, control bread had a lower (p0.05), bread containing xanthan gum had a lower anisidine value than the other treatments. Sensory analysis found bread with both gums to be moister (p

The antioxidants BHA, BHT, and ascorbic acid were added to flaxmeal breads to prevent rancidity. Six types of yeast leavened breads were evaluated: control (100% bread flour), flaxmeal (15%) bread, and flaxmeal (15%) bread that contained 0.01% respectively of BHA, BHT, BHA and BHT, and ascorbic acid. Vital wheat gluten was added in all the flaxmeal breads. Chemical, objective and sensory tests were used to evaluate the breads. The crumb texture of all the experimental breads was significantly softer (p¡à 0.05) than the control breads, but the control breads were significantly moister (p¡à 0.05) than the flaxmeal breads that contained BHA and BHT, separately. No significant differences (p>0.05) were found in loaf volume of the control bread and the experimental breads. The crumb color of the experimental breads was significantly darker (p0.05) were found in peroxide values between the control breads and experimental breads after eight weeks. The QDA sensory tests showed that breads containing BHA or in combination with BHT were moister, chewier and had the least noticeable stale taste when compared to the control breads. Ascorbic acid was not as effective as BHA or a combination of BHA and BHT in preventing lipid oxidation, but produced the softest bread. This study showed that flaxmeal breads made with BHA and BHT provided the best protection against lipid oxidation and produced a moist and chewy bread. Master of Science

The effect of soy as a natural antioxidant against flaxseed rancidity in yeast breads was tested. Variables included: control (100% bread flour); yeast bread with 15% flax meal in place of part of the total bread flour; yeast bread with 15% flax meal and 5% soy; and yeast bread with 15% flax meal and 10% soy. Objective and sensory tests were used to evaluate breads. Peroxide values indicated that the hydroperoxides in breads increased during the first four weeks of the study, and then decreased, as would be expected as breads are exposed to more elements with time. Moisture content was not significantly different between the breads. Breads containing flax were significantly firmer (p < 0.02) in texture. Breads containing flax were also significantly lower in volume (p < 0.005) and significantly darker in crumb color (p < 0.01). The level of 10% soy contributed to a significantly darker crust color (p < 0.04). Quantitative descriptive analysis (QDA) found the level of 10% soy also contributed to an increased stale taste and aftertaste, firmer texture, coarser crumb, and drier loaf (p < 0.05). Musty aroma was not significantly different among breads and all breads containing flax had an increased grainy taste (p < 0.0001). Soy was found to have no significant antioxidant effect on the prevention of flaxseed rancidity in yeast breads. Master of Science

The performance of three different lipid/hydrocolloid coatings was tested on Golden Delicious apples. The coatings consisted of a mixture of lipid, wax, and various gum blends. The three treatments were compared to an uncoated group (control). Both objective and sensory tests were performed to determine the shelf-life stability of the apples. Objective results indicated that all three treatments significantly decreased (P0.0083) among the groups with regard to soluble solids and fresh weight loss. Externally, the treated apples had a significantly greener hue (Hunter color "a") than the control apples, however, there were no significant differences (P>0.0083) in yellow color (Hunter color "b") between the groups. Sensory results indicated that the treated apples were firmer, crisper and juicier (P0.0083) in the sweetness, tartness, and appearance of all of the groups. Overall, the derived coatings could serve as a resource for extending and maintaining the shelf life of perishable fruit. Master of Science

Durum wheat (Triticum durum Desf.) is produced primarily in the Northern Great Plains and the Pacific Southwest of the United States. Current germplasm is predominantly of the spring growth habit. The objective of this study was to determine the feasibility of winter durum production in Virginia based upon both yield and quality parameters. Adaptation and yield potential of available winter durum lines were assessed from 1993-1998, in three physiographic regions in Virginia. The highest average durum yields were produced in the northern piedmont plateau at the Orange County location. Winter durum yields generally averaged 1600-2800 kg/ha less than soft red winter wheat, traditionally grown in the state. The price premium for high quality durum can compensate for this difference in yield. Based on average durum yields, and assuming the grain meets U.S. No. 2 Hard Amber Durum standards, durum production in Virginia would have been more profitable than soft red winter wheat production in 1994 and 1997. Physical and chemical quality analyses of the top 19 performing durum lines were performed to determine grain marketability, suitability for pasta, and potential consumer acceptance of the end product. Protein content and gluten strength of the Virginia grown durum were acceptable. Color, firmness, and cooking loss of pasta produced from Virginia grown durum were comparable to pasta produced from commercial semolina. Requirements for U.S. No. 2 Amber Durum were met by 21% of the lines in both 1996 and 1997. Overall, the wet, humid Virginia climate was the greatest hindrance to durum production and quality. The field trials and quality analyses showed that high quality durum production in Virginia is possible, but not consistent over all years. Master of Science

The performance of a maltodextrin gel as a replacement (25, 50, 75, and 100%) for shortening along with high-fructose corn syrup-90 (HFCS-90), adjusted for sweetness in each treatment, were evaluated in a high-ratio white-layer cake formulation. Two controls were used to compare to fat-replaced cakes: control A (100% fat with 100% sucrose) and control B (100% fat with 50% sucrose/50% HFCS-90), which closely matched the sugar system of the fat-replaced cakes. Objective tests indicated that treatments D (50%), E (75%), and F (100%) had significantly higher (P

Nymphaea petersiana Klotzsch (Nyika) is an important wild tuber eaten in some districts of Malawi. The tubers were processed by boiling/freeze-drying(BFD) and sun-drying(USD). The tuber's nutrient and antinutrient composition was determined to produce a preliminary nutrient data base for use in sub-Saharan Africa. There was no significant difference (P > 0.05) in protein content of BFDand USD samples. Sun-dried samples were significantly (P < .05) higher in ash than boiled samples while boiled samples were significantly higher (P < .05) in crude fat and total carbohydrate. The protein content of the tubers (8.0 and 8.1 %) was higher than that of the staple maize (7.9%), African millets (unspecified) (7.5%), and polished rice (7.0%), but lower than sorghum (10.7%). Protein content was higher than tubers like cassava (1.3%), potato (2%), sweet potato (1.6%), yams (1.5%) and N. lotus (5.2). Nyika tubers have a well balanced amino acid content, limiting only in lysine. There were no significant (P > 0.05) differences in the mineral content of BFD and USD samples, except for iron, which was lower in the boiled samples. Nyika tubers have a higher calcium (1376 and 946 ug/g) and phosphorus (2250 and 2883 ug/g ) content than wild and domesticated cassava, potatoes, sweet potatoes and wild and domesticated yams. Sun-dried tubers have a higher iron content (88ug/g) than maize (20ug/g). The zinc content of tuber was higher (21and 25ug/g) than that of boiled maize flour, boiled sorghum flour, rice, cassava, and sweet potato. The predominant fatty acids in the tubers were oleic (47%), linoleic (32%), palmitic (21%) and linolenic (7%) acids. Ascorbic acid content was very low, only 0.1 and 0.003 mg/100g. Tannin content was lower (1 and 1.7 %) in the tubers than in Vulgare Pers. sorghum, DeKalb sorghum from U.S. and Kabale sorghum from Uganda. There was a significantly (P < 0.05) lower content of phytate in boiled (3.9ug/g) than in sun-dried tubers (6.0 ug/g). Phytate content of the tubers was lower than that of cooked maize flour, unrefined maize flour, cassava and sweet potato. Trypsin inhibitor activity in the tubers was reduced from 463 to 55 TIU/g tuber and chymotrypsin inhibitor activity was reduced to 50 from 267 CIU/g tuber by cooking. Nyika is a good source of iron and quality protein limiting only in lysine. Protein is comparable to staple maize and higher than root crops consumed in Malawi. It is not a good source of fat and ascorbic acid. Tannin, phytate, trypsin, and chymotrypsin inhibitor content lower than most food crops consumed in Malawi. Ph. D.

The antioxidant properties of various blends of rosemary extract and tocopherols, either alone or with citric and ascorbic acid, were compared in filleted, headed and gutted, and minced rainbow trout (Oncorhynchus mykiss). The filleted and headed and gutted products were stored at -29 degrees C for twelve months, while the minced was stored at the same temperature for 24 weeks. Oxidation was measured by following changes in thiobarbituric reactive substances, conjugated diene hydroperoxides, texture, drip loss, pH, sensory evaluation, and gas chromatographic detection of aldehydes. Natural antioxidants, in particular those that contained citric and ascorbic acids, were effective at retarding the development of conjugated diene hydroperoxides and malonaldehyde (p

Two lipid-based edible coatings, Apex B (AC Humko, Memphis, TN) and Durafresh (Pacrite, Ecoscience Produce Systems, Orlando, Fl) were evaluated for their ability to preserve post harvest quality changes in green bell peppers (Capsicum annum L. cv. King Arthur). Post harvest storage quality conditions tested included respiration rates, weight, color and texture changes, and stability of ascorbic acid (AA) and dehydroascorbic acid (DHA) content. Results indicated that no appreciable changes between days or treatment groups occurred in three of the parameters tested: weight, texture, and hue angle (p>0.05 for all parameters). Significant weekly changes were seen in respiration rates, dehydroascorbic acid content, and chromaticity values. Respiration rates and DHA were significantly higher during the last two weeks of the study (p=0.0001, p=0.0001 respectively). Chromaticity values were significantly lower, indicating a more faded color on the 14th day of the study alone (p=0.0097). Initial AA levels were much lower than expected (average initial content=78.72mg/100g). Significant differences between coated and uncoated pepper groups were seen in AA and DHA levels. AA content was found to be significantly lower in coated peppers (p=0.0279), while DHA levels were significantly higher in coated groups (p=0.0126). Overall, coated groups differed little from uncoated counterparts, except in the area of vitamin content in which the coated peppers showed an increase in vitamin breakdown. Despite the results, modifications of lipid coatings are needed, such as creating bilayer and composite coatings that contain either polysaccharide or protein constituents to enhance coating effectiveness. Master of Science

The food industry has responded to the American Heart Association's overwhelming concerns about the complications of obesity with an array of fat reduced products that maintain the functionality of fat in given systems. In baked products, it appears that no one single ingredient effectively mimics these functions. The present study investigated the effect of liquid or dry honey as a partial replacement for sugar on the baking and keeping qualities of fat reduced muffins. The fat reduced muffins also utilized a hydrocolloid fat replacer, bacterial and fungal amylases, and an emulsifier (DATEM). Results showed that both liquid and dry honey significantly (p0.05) affected but appeared to decrease with the addition of honey due to either premature starch gelatinization or a decrease in batter pH. The addition of honey increased moisture content, and decreased water activity, but did not decrease firmness or staling rates especially after prolonged frozen storage. Sensory panelists noted that the addition of liquid or dry honey increased the cohesive forces and decreased tenderness. The addition of moisture to the fat reduced system did not appear to improve the perceived moistness of the product. Master of Science

Nine 1B/1R translocated soft red winter wheat (SRWW) varieties and six non-1B/1R varieties from two crop years (1995-1996 and 1996-1997), grown in two Virginia locations (Warsaw and Blacksburg), were studied to evaluate the effects of the 1R rye chromosome on soft wheat flour quality and baking performance. The presence of the 1B/1R chromosomal translocation in wheat has been reported to provide disease resistance, but produce sticky doughs. The 1995-1996 and 1996-1997 SRWW flours were subjected to farinograph analysis and dough stickiness testing. Dough stickiness was determined by the Schwarzlaff-Shepherd Dough Stripping Method. Wheat samples from 1995-1996 were also analyzed for protein, ash, and moisture content, alkaline water retention capacity (AWRC), cookie diameter, tensile stress and strain, and by ¹³C nuclear magnetic resonance (¹³C-NMR) spectroscopy techniques. Significant (p = 0.0001) negative correlations were found between AWRC and cookie diameter of SRWWs grown in Warsaw and Blacksburg. Location was found to exert a significant effect on AWRC, cookie diameter and stickiness (p < 0.05). Farinograph data revealed that mixing characteristics of SRWW were affected significantly by variety, crop year and location (p < 0.05). In some cases the 1B/1R varieties had lower breakdown rates, longer departure times (DT) and lower mixing tolerance index (MTI), than their non-1B/1R counterparts. There was a significant difference (p = 0.0133) in the stickiness of 1B/1R and non-1B/1R samples from Blacksburg. However no such difference was found in the corresponding Warsaw samples (p = 0.9826), indicating that location exerted a significant effect on stickiness. Two flour samples exhibiting stickiness (one with and one without 1B/1R) and two non-sticky samples (one with and one without the 1B/1R) were fractionated into gluten, starch and water-solubles (WS) in order to determine if the sticky dough factor resided in the 1B/1R and / or non-1B/1R WS. The peel time of the interchanged samples, as in the case of 'Massey' flour combined with the WS from VA52-22, increased to 79 seconds from the 30 seconds originally observed in the Massey flour. However when gluten and starch fractions from a non-sticky, non-1B/1R sample,VA54-21, were mixed with WS from VA54-211 (sticky, 1B/1R), the peel time went from 18 in the original flour to 8 seconds. Tensile measurements showed dough stress was not significantly affected by the presence or absence of 1B/1R (p = 0.7057). However, dough strain was lower in 1B/1R translocated SRWWs (p = 0.0048). A ¹³C-NMR spectra failed to show differences amongst selected 1B/1R and non-1B/1R dough samples. Proton relaxation time (T1-rho-[H]) - a ¹³C-NMR technique, indicated that water did not exert a significant influence on the molecular dynamics within the dough samples of Massey (non-1B/1R), VA54-211 (1B/1R) and VA52-22 (1B/1R). However, the non-sticky, non-1B/1R sample (VA54-21) had a higher proton relaxation time at 62 ppm which may indicate the size of starch-protein particles in VA54-21 doughs were larger and less flexible than in the other three doughs. Ph. D.

Utilization of a fat substitute (100% replacement) with and without added fungal protease, fungal amylase, and bacterial amylase in a muffin was compared to a full fat counterpart. The enzymes were evaluated independently and in combination with each other. Physical and sensory data were reported with a p0.05) among any of the variations in volume, water activity (freshly baked, and after 24 and 48 hours storage), crumb L values and crust Land b values. The full fat muffin (control) was significantly (p

Wheat (Triticum aestivum L.) is one of the major cereals of the world. Farmers must produce wheat with good yield and quality to meet the high demands for wheat flour. To reduce disease and increase wheat yield, cultivars have been developed by replacing the short arm of chromosome 1B of wheat with the short arm of the 1R chromosome from rye (Secale cereale L.). This wheat-rye translocation, 1B/1R, carries linked genes which makes these wheat cultivars more disease resistant and higher yielding. Unfortunately, the 1B/1R translocation in hard wheats has been shown to produce undesirable characteristics such as dough stickiness and reduced mixing tolerance. Many promising wheat lines have been developed by crossbreeding 1B/1R Jines with soft wheat in hopes of producing a 1B/1R soft wheat of good quality for use in soft wheat products. The purpose of this research was to determine the end use quality of flours from soft red winter wheats possessing 1B/ 1R. Fourteen soft wheat varieties (7 without 1 B/1 R and 7 with 1B/lR) grown in two Virginia locations, Warsaw and Blacksburg, were assessed for flour quality and dough stickiness. Four pairs of the experimental wheats were sister lines. Flour quality was evaluated by means of protein content, farinograph analysis, cookie spread and protein analysis. Dough stickiness was measured using the "Schwarzlaff-Shephard Dough Stripping Method", specially designed for this study. It is the first method of its kind to measure dough stickiness quantitatively. Results indicated that the 1B/1R translocation, in general, had no adverse effect on flour quality and dough stickiness of the experimental wheats and even improved mixing tolerance and stability of the wheat flour doughs. The results of the study indicate that flours of 1B/lR wheats can be used in commercial soft wheat bakery formulas. Ph. D.

Performance of three carbohydrate-based fat replacers (pectin, gum, and oat fiber) in a southern-style baking powder biscuit was evaluated at substituted levels of 33%, 66%, and 100%. Objectives and sensory tests were conducted on all samples. Results were compared to the control for the determination of significant differences at (p