Effect of prickly pear and algarrobo pod syrup coatings on consumer acceptance and stability of roasted almonds

BACKGROUND: The objective of this study was to evaluate the oxidative stability of roasted almonds coated with prickly pear and ‘algarrobo’ pod syrups and the effect of these coatings on consumer acceptance. RESULTS: Prickly pear syrup had higher moisture, proteins, ashes and lipids, and lower carbohydrate content, than algarrobo pod syrup. Phenolics and antioxidant activity such as inhibition percentages of diphenyl picryl hydrazyl radical were higher in prickly pear syrup than algarrobo pod syrup. Roasted almonds had higher protein and lipid contents and lower total carbohydrates than coated almonds. Three main fatty acids detected in all almond products were palmitic (63.2 g kg^?1), oleic (727.0 g kg^?1) and linoleic (208.0 g kg^?1) acids. The overall acceptance means in roasted almonds, roasted almonds coated with prickle pear syrup and roasted almonds coated with algarrobo pod syrup were 6.83, 6.65 and 6.70, respectively, on a 9‐point hedonic scale. The peroxide and anisidine values increased in all products. The increase was higher in roasted almonds without coating. CONCLUSION: These results indicated that the syrup coatings provided protection against lipid oxidation in almond products. Prickly pear syrup showed better protection against lipid oxidation. Copyright © 2009 Society of Chemical Industry     

IMPROVEMENT OF OXIDATIVE STABILITY OF ROASTED PEANUTS BY EDIBLE COATINGS AND ULTRASONICATION

In this study, an innovative method was developed to improve the shelf life of roasted peanuts. Sonication was combined with edible coating for enhancing the oxidative stability of roasted peanuts. Georgia green runner peanuts were roasted, subjected to sonication and then coated with whey protein isolate (WPI), ZEIN and carboxymethyl cellulose (CMC). Relative to the control, the oxidative stability of roasted-coated samples was improved by 80, 38 and 5% for CMC, WPI and ZEIN coating, respectively, while roasted-sonicated-coated samples were improved by 91, 52 and 27% for CMC, WPI and ZEIN coating, respectively. Sonication prior to coating resulted in 11, 14 and 22% improvement beyond the CMC, WPI and ZEIN coatings, respectively. Texture analysis showed there were no significant differences ( P <  0.05) in peanut texture between the treated and the control. Color results showed the HunterLab color parameters L, a, and b for most of the treatments did not have significant differences ( P <  0.05) compared with the control.

PRACTICAL APPLICATIONS

Edible coatings used in this study (carboxymethyl cellulose, whey protein isolate and ZEIN) were capable of acting as oxygen barriers to reduce peanut lipid rancidity. This research demonstrated the potential of power ultrasound to remove lipids from the peanut surfaces and improve coating adhesion. The texture and the color of coated peanuts did not change over the storage period. This study indicated that edible coatings in combination with sonication provided an alternative way for improving the oxidative stability and eventually the shelf life and quality of roasted peanuts.     

Preserving sensory attributes of roasted peanuts using edible coatings

Peanut products are susceptible to develop rancid and off‐flavours through lipid oxidation. Preservation of these products is one of the problems in the peanut industry. The purpose of this work was to determine the sensory and chemical stability of roasted peanuts (RP) coated with different edible coatings: carboxymethyl cellulose (RP‐CMC), methyl cellulose (RP‐MC) or whey protein (RP‐WPI) during storage. Sensory attributes and chemical indicators (peroxide and p‐anisidine values, and conjugated dienes) of lipid oxidation were measured during storage. Chemical indicator values and intensity ratings of oxidised and cardboard flavours had lower increase in RP‐CMC, RP‐MC and RP‐WPI during storage than in RP, whereas roasted peanutty flavour showed a lower decrease. The stability of RP‐CMC is about a double longer with respect to RP. These results indicate that edible coatings preserve the sensory properties of roasted peanuts. Carboxymethyl cellulose exhibited the best protecting effect on this product.     

Antioxidant effect and characterization of South American Prosopis pods syrup

The traditional syrup made of Prosopis pods, known as “algarrobina” or “arrope de algarrobo” in the Andean countries, is commonly used in confectionery and local cuisine to prepare sweets and cocktails. The polyphenolic content of four Prosopis pods syrup samples as well as from the phenolic-enriched Amberlite-retained fraction of the syrup, were analyzed using reversed phase high performance liquid chromatography-diode array detector coupled to electrospray ionization mass spectrometry (HPL-DAD-ESI-MS). The main phenolics in the syrups were apigenin-derived C-glycosyl flavonoids, including 6,8-C-pentoside-C-hexoside, 6,8-dihexoside and quercetin glycosides. The sugar derivative 5-hydroxymethyl furfural was present in most of the samples. All syrups were devoid of cytotoxicity towards human lung fibroblasts and human gastric AGS cells, with IC₅₀ values > 1000 μg/mL. The phenolic constituents of the syrups are C-glycosylflavonoids with known anti-inflammatory, antioxidant and other nutraceutical properties. The phenolic composition of South American algarrobo syrup is presented for the first time.     

EFFECT OF CHOCOLATE COATING ON OXIDATIVE STABILITY OF NORMAL AND HIGH OLEIC PEANUTS

Oxidative stability studies were performed on roasted high-oleic acid peanuts (HOP-SunOleic 95) and normal oleic acid peanuts (NOP-Florunner). Peanuts were dry-roasted to a Hunter Lab value of approximately 50. Chocolate-coated peanut bars (6"x4"×1/2") were prepared using milk chocolate, white chocolate, and reduced-fat chocolate (containing salatrim). Chocolate bars were stored at 25C and 0.60 water activity (a_w). Uncoated peanuts were stored at 0.60 and 0.19 a_w at 25C. Samples were removed from storage at 4-week intervals for peroxide value measurement. Oxidation of peanuts with chocolate coatings were higher than the peanuts that were stored uncoated at the same a_w. The peroxide values of NOP were similar for chocolate coated treatments and 0.60 a_w control but the 0.19 a_w control was 2–4 times higher than the others. Chocolate-coated peanuts had higher oxidation rates compared to uncoated peanuts.     

Effects of Sonication and Edible Coating Containing Rosemary and Tea Extracts on Reduction of Peanut Lipid Oxidative Rancidity

Rancidity due to the lipid oxidation process is a critical factor influencing the quality of roasted peanuts. Sonication in combination with edible coatings added with plant extracts may extend the oxidative stability of peanuts. Peanuts were roasted at 178°C for 15 min, subjected to sonication in hexane for 10 min, and then coated with carboxymethyl cellulose (CMC) solution mixed with rosemary, tea extracts, and α-tocopherol and stored at 35°C for 12 weeks. The oxidative stability of the samples was investigated by measuring the oxidative stability index. Reduction in oxidation of 66.1% and 10.4% was observed for samples roasted and coated with extracts of rosemary and tea, respectively, as compared to uncoated sample. However, the oxidative stability of samples roasted–sonicated and coated with extracts of rosemary and tea was improved by 100.7% and 28.1%, respectively, in relation to the control. Sonication beyond coating improved the oxidative stability of the samples mixed with rosemary, tea extracts, and α-tocopherol by 10.3%, 12.1%, 34.6%, and 17.7%, respectively. The L ^* , a ^* , and b ^* values indicated that the peanut coated with CMC mixed with rosemary, tea extracts, and tocopherol at different concentration levels did not have significant (P < 0.05) color change during the 12-week storage at 35°C.     

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.     

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.     

FLUIDIZED-BED SYSTEM FOR WHEY PROTEIN FILM COATING OF PEANUTS

Complete peanut‐surface coverage and strong adhesion are necessary for whey protein‐based oxygen barrier coatings to be totally effective in reducing the oxidative rancidity of peanuts. Peanuts coated with a fluidized‐bed coating system attained practically complete coverage, and coating efficiency results were consistent and reproducible. Addition of surfactant to the coating solution improved whey protein coating efficiency on blanched/roasted peanuts coated with a bench‐scale fluidized‐bed coating system. A lower level of surfactant addition to the coating solution was required to attain complete coverage, compared with previous studies on dip coating and pan coating of peanuts. Addition of surfactant to the coating solution and peanut preroughening both imparted good coating adhesion for fluidized‐bed‐coated peanuts. Compared with pan coating, fluidized‐bed coating required application of a greater amount of coating solution because of the loss of coating solution to the fluidized‐bed column wall during spraying. Overall, fluidized‐bed coating required a shorter processing time and provided the peanuts with better coating efficiency and adhesion. These results suggest that a fluidized‐bed coating system is a viable alternative coating process for whey protein coating of peanuts.     

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.     

Physical and Antioxidant Characterization of Edible Films Added with Red Prickly Pear (<Emphasis Type="Italic">Opuntia ficus-indica</Emphasis> L.) cv. San Martín Peel and/or Its Aqueous Extracts

The aim of this research was to investigate the effect of the addition of peel powder and/or its aqueous extract on physical and antioxidant characteristics of carboxymethyl cellulose (CMC) edible films. Prickly pear peel powder and aqueous extract (2 and 4%) were characterized in color, bioactive compounds (betalains and total phenolic compounds), antioxidant capacity and reducing power. Edible films were prepared with CMC, glycerol, varying the dissolution medium (0, 2, or 4% aqueous extract from prickly pear peel) and peel powder (0, 1, or 2%) using a face-centered central composite design. Physical, mechanical, bioactive compounds, and antioxidant capacity properties were investigated in edible films. Prickly pear peel powder presented 58.8 ± 0.08 mg of betacyanins/100 g, 53.8 ± 0.2 mg of betaxanthins/100 g, 967.8 ± 20 mg Gallic acid equivalent (GAE)/100 g for total phenolic compounds, an antioxidant capacity equivalent to 420.9 ± 4.9 mg GAE/100 g and a reducing power of 879.1 ± 115.9 mg ascorbic acid equivalent (AAE)/100 g. High concentration of aqueous extract and peel powder in CMC films increased the bioactive compounds content, antioxidant capacity and reducing power. Films mechanical properties were not affected by the aqueous extract; nevertheless, were strongly affected by the peel powder. Response surface methodology was used to optimize edible films formulation with high antioxidant characteristics, being the optimal formulation 1.7% of peel powder plus 3.3% of aqueous extract. This study may be the base for exploitation of prickly pear peel as source of bioactive compounds with antioxidant capacity for their use in edible coatings.     

EDIBLE COATINGS COMPOSED OF METHYLCELLULOSE, STEARIC ACID, AND ADDITIVES TO PRESERVE QUALITY OF PEAR WEDGES

The ability of methylcellulose and methylcellulose-stearic acid coatings to preserve the quality of Anjou pear wedges stored at 4C and 78% relative himidity over a period of 12 days was assessed. The effect of some additives (ascorbic acid, calcium chloride, and sorbic acid) alone or in combination with the edible coatings was also evaluated. The use of edible coatings and additives prolonged the shelf life of treated samples by retarding browning and enhancing texture when compared to control samples. Methylcellulose-stearic acid coatings played an important role in avoiding weight loss, while methylcellulose-only coatings showed poor water vapor barrier properties. Pear wedges coated with the methylcellulose-stearic acid formulation contained higher amounts of hexyl acetate throughout the storage period, probably due to synthesis by wounded tissue from the stearic acid contained in the coating. No effect from the applied treatments on the titratable acidity, soluble solids content, and microbial load of treated pear wedges was found.     

Flavor and Oxidative Stability of Peanut-Sesame-Soy Blends

Five spreads were formulated from roasted high‐oleic acid peanuts and sesame paste (HOPS), normal‐oleic acid peanuts and sesame paste (NOPS), high‐oleic acid peanuts, sesame paste and soy (HOPSS), normal‐oleic peanuts, sesame paste and soy (NOPSS), and normal‐oleic acid peanuts only (NOP). Spreads were evaluated during 12 wk at 40 °C for sensory attributes: roast peanut, sesame, sweetness, bitterness, cardboardy, and painty. Roast peanut and sesame flavor generally decreased, and HOPSS and NOPSS had lower roasted peanut flavor. Cardboardy and painty increased in NOP, and HOPS had the lowest cardboardy and painty flavors. Peroxide values increased, with the highest value in NOP and lowest in HOPS. Sesame paste limited oxidation in products containing NOP and soy.     

Inhibitory activity of aromadendrin from prickly pear (<Emphasis Type="Italic">Opuntia ficus-indica</Emphasis>) root on aldose reductase and the formation of advanced glycation end products

Prickly pear (Opuntia ficus-indica) is a longdomesticated crop plant of arid and semiarid parts of the world. The efficacy of extracts of prickly pear root for managing diabetes and diabetes complications was evaluated using a variety of in vitro bioassays. The ethyl acetate-soluble fraction was most effective in the prevention of diabetes and its complications via the inhibition of rat lens aldose reductase activity, the formation of advanced glycation end products, and α-glucosidase activity. MS and NMR were used to identify the bioactive compound from the ethyl acetate-soluble fraction as 3,5,7,4′-tetrahydroxyflavanone (aromadendrin).     

COMPARISON AMONG GLUTEN,MALTODEXTRIN, AND SOYBEAN OIL COATINGS AS FLAVOR CARRIERS ON PITA CHIPS1

Dietary health concerns of consumers have prompted manufacturers to produce snacks with lower fat content. Reduced fat products need additional ingredients to compensate for flavor loss. Gluten and maltodextrin coatings were compared with soybean oil as a carrier of cheese powder on pita chips. Coated pita chips were packaged with or without nitrogen and stored at 33C and 50% humidity for 60 days. Physical, chemical, microbiological, and sensory properties of the chips were evaluated. Saturation index and hue angle were significantly different at 30 and 60 days for all treatments. Instrumental texture analysis was inconclusive due to high standard deviations. Peroxide value for oil‐coated chips increased significantly over time. Consumer acceptance testing indicated a stronger cheese flavor for maltodextrin and gluten treatments compared with oil. No off‐flavors were detected from any chips. Microbial counts were low and did not differ significantly among treatments. Gluten and maltodextrin coatings may be alternative flavor carriers to oil for reduced fat content in snack foods.     

'Flavor-fade' and Off-Flavors in Ground Roasted Peanuts As Related to Selected Pyrazines and Aldehydes

Headspace volatiles from ground roasted Florunner medium peanuts, stored at 65°C for 1–68 days, were separated and identifled by GC/MS. Selected pyrazines, resulting from Maillard browning and selected aldehydes from autoxidation were evaluated to determine their mechanistic contributions to peanut ‘flavor-fade.’ The 2,6-dimethylpyrazine, 2-methylpyrazine, 2-ethyl-5-methyl or 6-methylpyrazine, 2,3,5-trimethylpyrazine, and pentanal remained constant during storage (p < 0.05). Flavor scores for ‘roasted peanut’ decreased slightly, then leveled off and hex-anal, heptanal, octanal and nonanal increased during storage (p < 0.05). Oxidative ‘rancid’ flavor scores and thiobarbituric acid values also increased during storage (p < 0.05). Based on results, the ‘flavor-fade’ of stored roasted peanuts is due to masking of pyrazines and other ‘roasted peanut’ flavor compounds by large quantities of low-molecular weight aldehydes from lipid autoxidation, and not due to polymerization and/or degradation of the pyrazines.