Oxidative Stability in Raw and Roasted Pecans: Chemical, Physical and Sensory Measurements

To develop predictive relationships for sensory responses of crunchiness and rancid aroma and flavor, raw and roasted pecans were stored under two different relative humidities (55 and 65%) up to 8 mo. In response to relative humidity, rancid scores did not differ with either raw or roasted pecans. Rancid scores in raw and roasted pecans during storage most closely paralleled peroxide value and thiobarbituric acid reactive substances, respectively. Multiple regression models employing two or three oxidative and chemical measurements led to better prediction of sensory scores. In general, primary oxidative products of triacylglycerols factored into the models for raw pecans while secondary oxidative products of total lipids factored into the models for roasted pecans.     

Sensory, Microbiological and Chemical Quality of Mini-Peeled Carrots as Affected by Edible Coating Treatment

The effect of three application rates of an edible cellulose-based coating on sensory, microbiological and chemical quality of mini-peeled carrots was studied during storage at 2°C. Carrots treated with edible coating had reduced levels of white surface discoloration, and higher sensory scores for orange color intensity, fresh carrot aroma, fresh carrot flavor, and overall acceptability than non-coated carrots. Edible coating treatment did not affect levels of total aerobic microorganisms, yeast, mold or lactobacilli. Oxygen, carbon dioxide and ethanol levels in packages, and sugar and soluble phenolic content of mini-peeled carrots were not affected by coating treatment. An edible coating application rate of 0.23–0.49 L/min protected against surface discoloration and retained quality during storage at 2°C.     

Maturity Effects on Sensory and Storage Quality of Roasted Virginia-Type Peanuts

Virginia-type peanuts from two yrs were studied to determine differences in sensory and storage characteristics of five mesocarp-color based maturity classes. Peanuts were roasted, stored at 37°C, and sampled over 12 wk to evaluate flavor and oil. Higher intensities of roasted peanutty and sweet and lower painty flavors were found in the most mature classes. Painty increased more quickly in immature classes. Oxidative stability and fatty acid profiles indicated this change. Immature peanuts had lower flavor impact and deteriorated faster. Distributions at progressive harvest dates indicated more immature peanuts in the Extra Large Kernel grade at early harvest. Variability in sensory characteristics of maturity classes and changes in their distribution in size-based commercial grades indicate a high potential for maturity related flavor variation between lots.     

Ultrasonication and Edible Coating Effects on Lipid Oxidation of Roasted Peanuts

Lipid oxidation is an important factor affecting the quality of roasted peanuts. Coatings applied to the peanuts can enhance oxygen barriers to reduce rancidity. Ultrasonication was used to remove lipids from the peanuts prior to applying the coating to improve attachment of the coating on the peanut surface. Peanuts were roasted at 178°C for 15 min and then sonicated in hexane for 10 min. Whey protein isolate (WPI) 11%, corn protein (Zein) 15%, and carboxymethyl cellulose (CMC) 0.5% were used as coating materials. Sample treatments were: (1) roasted–coated with CMC (RCMC), WPI (RWPI), and Zein (RZEIN); (2) roasted–sonicated–coated with CMC (SCMC), WPI (SWPI), and Zein (SZEIN); (3) roasted–uncoated (R) as a control. Oxidative stability was investigated by gas chromatography–mass spectrometry (GC–MS) to detect formation of volatile compounds. The GC–MS indicated an eightfold, fivefold, and fourfold increase in hexanal formation in R, RZEIN, and SZEIN samples, respectively. But there was 80%, 91%, 18%, and 66% decrease in hexanal formation in RCMC, SCMC, RWPI, and SWPI samples, respectively, as compared to R. Sonication increased capability of coatings to delay hexanal formation by 11% and 48% for CMC and WPI, respectively, as compared to nonsonicated samples. Thus, the coating in combination with ultrasonication treatment was an effective method in delaying formation of oxidative volatile compounds and hence inhibiting rancidity of roasted peanuts.     

Whey Protein Coating Effect on The Oxygen Uptake of Dry Roasted Peanuts

A procedure was developed to coat peanuts with aqueous whey protein isolate (WPI) solutions based on increasing coating-solution viscosity. Oxygen uptake of WPI-coated nuts and uncoated nuts were compared. WPI coatings delayed oxygen uptake of dry roasted peanuts at intermediate (53%) and low (21%) storage relative humidity. They had similar results at 29°C and 37°C. The effects of coating thickness and storage relative humidity indicate that the mechanism of protection of the coatings was through their oxygen barrier properties.     

Coating of Peanuts with Edible Whey Protein Film Containing α‐Tocopherol and Ascorbyl Palmitate

ABSTRACT: Physical properties of whey protein isolate (WPI) coating solution incorporating ascorbic palmitate (AP) and α‐tocopherol (tocopherol) were characterized, and the antioxidant activity of dried WPI coatings against lipid oxidation in roasted peanuts were investigated. The AP and tocopherol were mixed into a 10% (w/w) WPI solution containing 6.7% glycerol. Process 1 (P1) blended an AP and tocopherol mixture directly into the WPI solution using a high‐speed homogenizer. Process 2 (P2) used ethanol as a solvent for dissolving AP and tocopherol into the WPI solution. The viscosity and turbidity of the WPI coating solution showed the Newtonian fluid behavior, and 0.25% of critical concentration of AP in WPI solution rheology. After peanuts were coated with WPI solutions, color changes of peanuts were measured during 16 wk of storage at 25 °C, and the oxidation of peanuts was determined by hexanal analysis using solid‐phase micro‐extraction samplers and GC‐MS. Regardless of the presence of antioxidants in the coating layer, the formation of hexanal from the oxidation of peanut lipids was reduced by WPI coatings, which indicates WPI coatings protected the peanuts from oxygen permeation and oxidation. However, the incorporation of antioxidants in the WPI coating layer did not show a significant difference in hexanal production from that of WPI coating treatment without incorporation of antioxidants.     

Flavor and Oxidative Stability of Roasted High Oleic Acid Peanuts

A new peanut line has been developed at the University of Florida with about 80% oleic and 3% linoleic acid. Volatiles and sensory characteristics of roasted normal and high oleic acid peanuts stored at 25°C were compared. Volatiles were analyzed using adsorbent trapping and GCMS, a 20-member trained panel was used for sensory evaluation, and a GC sniffer port was used to evaluate odor characteristics of volatile isolates. Peroxide values were lower for high oleic (HO) peanuts than normal peanuts during storage at 25°C and 40°C. The hexanal content of the peanuts was higher for normal than HO. Peanutty flavor was more stable for HO than normal after 6 wk storage. Painty and cardboard flavors were higher in normal peanuts than HO during storage. Differences for both painty and cardboard flavors were significant after 6 wk storage. Pyrazines were more stable in HO peanuts. Shelf life was estimated from sensory data to be two times longer in HO peanuts.     

Vitamin E and Oxidative Stability During Storage of Raw and Dry Roasted Peanuts Packaged under Air and Vacuum

ABSTRACT: The relationship between vitamin E and the oxidative stability of raw and dry roasted peanuts was studied during storage at 21°C under air and vacuum. Lipid oxidation was monitored by peroxide values (PVs) and conjugated diene values (CDVs). In air, PV (meq/kg) for roasted peanuts reached 47 by 12 wk, whereas that for raw peanuts was below 2 after 38 wk. Under vacuum, lipid oxidation was significantly retarded ( P < 0.05). Tocopherols of raw and roasted peanuts exponentially decreased with increasing PV. After 12 wk, about 50% of α-tocopherol (α-T) was lost for roasted peanuts under vacuum compared with about 90% under air. For raw peanuts, more than 70% of each tocopherol remained after 38 wk under air and vacuum. In general, α-T showed the least stability in roasted peanuts compared with other tocopherols under the reported storage conditions.     

Chemical and Sensory Quality Preservation in Coated Almonds with the Addition of Antioxidants

Almonds provide many benefits such as preventing heart disease due to their high content of oleic fatty acid‐rich oil and other important nutrients. However, they are susceptible to oxidation reactions causing rancidity during storage. The objective of this work was to evaluate the chemical and sensory quality preservation of almonds coated with carboxymethyl cellulose and with the addition of natural and synthetic antioxidants during storage. Four samples were prepared: almonds without coating (C), almonds coated with carboxymethyl cellulose (CMC), almonds coated with CMC supplemented with peanut skins extract (E), and almonds coated with CMC and supplemented with butylhydroxytoluene (BHT). Proximate composition and fatty acid profile were determined on raw almonds. Almond samples (C, CMC, E and BHT) were stored at 40 °C for 126 d. Lipid oxidation indicators: peroxide value (PV), conjugated dienes (CD), volatile compounds (hexanal and nonanal), and sensory attributes were determined for the stored samples. Samples showed small but significant increases in PV, CD, hexanal and nonanal contents, and intensity ratings of negative sensory attributes (oxidized and cardboard). C had the highest tendency to deterioration during storage. At the end of storage (126 d), C had the highest PV (3.90 meqO₂/kg), and BHT had the lowest PV (2.00 meqO₂/kg). CMC and E samples had similar intermediate PV values (2.69 and 2.57 meqO₂/kg, respectively). CMC coating and the addition of natural (peanut skin extract) and synthetic (BHT) antioxidants provide protection to the roasted almond product.     

Minimal Processing and Edible Coating Effects on Composition and Sensory Quality of Mini-peeled Carrots

Coating treatment did not affect fresh carrot flavor or aroma, sweetness, bitterness, harshness or taste preference. Total terpenoids declined 72% after 17 days storage, with the major loss occurring within 3 days after minimal processing. α- and β-carotene declined 18% and 14% within 3 days after minimal processing with no further loss. Peel tissue contained less β-carotene than phloem tissue, and its removal was not responsible for loss of β-carotene. The edible coating did not affect terpenoid or carotene content.     

Sensory Quality and Performance of Spray-dried Coffee Whitener from Peanuts1

The feasibility of producing coffee whitener by spray drying peanut extracts was studied. The whiteners were spray-dried at 200°C using atomizer speeds of 15000, 25000, 35000 rpm and volumetric flow rates of 0.6, 1.2, 1.8 L/hr. Performance of the whiteners in coffee was evaluated vs commercial coffee creamers by a consumer panel. Objective tests for color, solubility, and moisture were performed. The liquid whitener had lower performance and sensory scores than commercial samples (p < 0.01). Recommended processing conditions for spray drying liquid whitener from peanuts at 200°C include atomizer speeds in the 15000-29000 rpm range and volumetric flow rates > 1.80 L/hr.     

Sensory, Physical, and Microbiological Properties of Liquid Whitener from Peanuts

Liquid whitener was prepared using peanut extract, cottonseed oil, and water. Quadratic canonical polynomials predicted the response of the sensory variables peanutty, milky, oily flavor, astringent, and surface layer thickness to the component proportions. Reduced cubic canonical polynomials were necessary to predict responses of the sensory variables color lightness, roasted nutty, oily suspension; and the variables viscosity and stability in coffee to the component proportions. Increasing or decreasing extract from 50% of the blend decreased whitening capacity. Increasing extract increased peanutty and roasted nutty ratings. Increasing oil increased ratings for oily flavor and surface layer thickness but decreased astringent ratings and stability of whiteners in coffee. Storage of the whitener at 5° was necessary to prevent mi-crobial spoilage.     

Enzymatic and Autoxidation of Defatted Peanuts

Ground, blanched, raw, and roasted peanuts with varying oil contents were analyzed for oxidation products. Peroxide values (PV) of blanched, ground raw (BRAW) peanuts, demonstrating enzymatic oxidation, and heat-treated rancid roasted peanuts (RRST), demonstrating autoxidation, exhibited decreases (p ≦ 0.05) with decreasing oil content. The Oxidative Stability Index (OSI) time at 110 °C increased (p < 0.05) with decrease in oil content of raw (BRAW) and roasted (BRST) ground peanuts. A higher OSI indicated more oxidative stability, thereby supporting the hypothesis of higher potential for autoxidation at higher oil contents. In addition, BRST exhibited a shorter OSI than BRAW, indicating slower autoxidation in BRAW. Roasted peanutty odor, burnt odor, and roasted peanutty flavor, rancid/oxidized flavor, and burnt flavor scores of rancid roasted peanuts decreased (p ≦ 0.05) with decreasing oil content.     

Oil Coating Affects Internal Quality and Sensory Acceptance of Selected Attributes of Raw Eggs during Storage

Four (coconut, palm, rice bran, and soybean) edible oils and glycerol were applied on eggshell. All noncoated and coated eggs were stored for 5 wk at 25 ± 2 °C and drawn weekly for quality evaluation. All oil coatings were more effective in preserving internal quality of eggs than was glycerol coating. As storage time increased, the preservative effects of edible oil coating on weight loss, and albumen and yolk quality were significantly noticed. Oil‐coated eggs had significantly lower weight loss (<0.43%) than did noncoated (3.87%) and glycerol‐coated (3.73%) eggs after 5 wk of storage. Based on the Haugh unit, oil‐coated eggs maintained AA grade up to 3 wk. After 5 wk of storage, noncoated, glycerol‐coated, and oil‐coated eggs changed from AA grade to below B, below B and A grade, respectively. The albumen pH of noncoated and glycerol‐coated eggs considerably increased from 8.23 to 9.51 and 9.42, respectively, while those of oil‐coated eggs either maintained or slightly increased to 8.32. The albumen viscosity of all eggs decreased with increased storage time. Consumers (N = 120) could differentiate surface glossiness of oil‐coated eggs from uncoated eggs (R‐index of 81.42% to 86.99%). All oil‐coated eggs were acceptable for surface glossiness (liking scores of 6.22 to 6.77) and surface odor (liking scores of 6.20 to 6.55) with overall liking scores of 6.34 to 7.03. Overall, this study demonstrated that edible oil (coconut, palm, rice bran, and soybean) coating could preserve internal quality of eggs (maintaining grade A) at least 4 wk longer than noncoated eggs. Practical Application: Freshness is a major contribution to the egg quality. The internal quality of eggs begins to deteriorate after they have been laid due to loss of moisture and carbon dioxide via the eggshell pores. Refrigeration is very effective in preserving egg quality. Surface coating is an alternative method to preserve egg quality, although it is much less effective than refrigeration. This study demonstrated that coconut, rice bran, soybean, and palm oils, which are abundant and commonly consumed in many parts of the world, could preserve the internal quality and reduce weight loss of oil‐coated eggs during room temperature storage.     

Correlation of Sensory, Instrumental and Chemical Attributes of Beef as Influenced by Meat Structure and Oxygen Exclusion

Correlation of elements contributing to meat flavor quality (MFQ) were examined. Muscle structure influences generation of micro temperature environments that lead to formation of flavor-zones. Generation of such zones was also attributed to a structurally-dependent barrier to oxygen. MFQ was examined in the presence and absence of oxygen. Vacuum storage completely retarded flavor deterioration as marked by chemical markers such as thiobarbituric acid reactive substances and lipid volatiles. Vacuum storage incompletely affected changes in sensory attributes; it partially retarded development of painty, cardboard, bitter and sour flavors and limited loss of desirable flavors such as cooked beef/brothy and browned/caramel. Bivariate plots of factor solutions resulting from multivariate principal components analysis proved a suitable method to graphically present statistical correlations between experimental treatments and sensory, chemical, and instrumental attributes.     

Physicochemical and Sensory Characteristics of Peanut Paste Stored at Different Temperatures

When peanut paste was stored at 30, 40 and 50°C for up to 1 yr, that held at 30°C for 161 days had minimal deteriorative changes. At 50°C, the primary deterioration was increased browning, oxidized and cardboard flavors, and oil separation. Regression analysis indicated that ratings for chroma, cooked peanut, cardboard, and oxidized flavors were responsible for > 50% of the variation in response. When a detectable oxidized flavor was used as the indicator of storage deterioration, peanut paste had a predicted shelf life of 152 days at 30°C; 98 days at 40°C; and 96 days at 50°C.