Soybean oil‐chitosan emulsion affects internal quality and shelf‐life of eggs stored at 25 and 4 °C

Effects of soybean oil (SO), chitosan solution (CH) and their emulsions (SO:CH = 60:40, 50:50 and 40:60 ratios) as coatings on internal quality of eggs stored at 25 and 4 °C, respectively, for 7 and 20 weeks, were evaluated. Eggs coated with SO and SO:CH emulsions maintained grade AA and/or A quality up to 7 weeks at 25 °C and 20 weeks at 4 °C, while noncoated eggs changed from AA to B grade after 2 weeks at 25 °C. Compared with noncoated eggs, shelf‐life of eggs stored at 25 °C was extended for 5 weeks by all SO:CH emulsions. Weight loss of eggs coated with SO:CH emulsions was <3% after 7 weeks at 25 °C and <5% after 20 weeks at 4 °C. SO:CH emulsion is alternatively an effective coating with possible shorter drying times for reducing weight loss and preserving the internal quality of eggs.     

Chitosan-soybean oil emulsion coating affects physico-functional and sensory quality of eggs during storage

Effects of soybean oil (SO) and chitosan-soybean oil (CH:SO = 40:60) emulsion as coating materials for preserving internal quality of eggs were evaluated during 7 and 15 weeks storage at 25 °C and 4 °C, respectively. Consumers (n = 150) assessed surface properties and purchase intent of freshly coated eggs. Noncoated eggs deteriorated from AA to B grade after 1 week while coated eggs retained A grade up to 5 weeks at 25 °C. Amongst coatings, CH:SO emulsion maintained a lower albumen pH while SO was better at reducing weight loss. Effect of refrigeration on albumen pH was minimal. Weight loss of coated eggs was <3% after 7 weeks at 25 °C. Emulsion capacity and emulsion viscosity were minimally affected by coating and refrigeration, and their trends were more correlated to the yolk index at 25 °C than at 4 °C. Only SO-coated eggs were not sensorially smoother than noncoated eggs; however, CH:SO emulsion-coated eggs had the least shell colour changes (ΔE^∗, values at day 0 as a reference) during storage at 25 °C. All coated eggs had 85% positive purchase intent. SO and CH:SO emulsion coatings significantly extended egg shelf-life compared to that of noncoated eggs at room and refrigerated storage.     

A novel emulsion coating and its effects on internal quality and shelf life of eggs during room temperature storage

Effects of mineral oil (MO), chitosan solution (CH) and their emulsions (MO:CH = 75:25, 50:50, and 25:75 ratios) as coating materials in preserving internal quality of eggs were evaluated during a 5‐weeks storage at 25 °C. Consumers (n = 109) evaluated surface properties and purchase intent of freshly coated eggs. As storage time increased, Haugh unit and yolk index values decreased whereas weight loss increased. Noncoated eggs rapidly changed from AA to B and C grades after 1 and 3 weeks, respectively. However, all emulsion‐coated eggs maintained their A‐grade quality for 4 weeks. Compared with noncoated eggs, all emulsion coatings reduced weight loss of eggs by at least seven times (0.88–1.03% vs. 7.14%). Only MO:CH = 25:75 emulsion‐coated eggs were not sensorially glossier than noncoated eggs. All emulsion‐coated eggs had >80% positive purchase intent and were negative for Salmonella. This study demonstrated that MO:CH emulsion coatings preserved internal quality and prolonged shelf life of eggs.     

Effects of initial albumen quality and mineral oil–chitosan emulsion coating on internal quality and shelf‐life of eggs during room temperature storage

Effects of mineral oil (MO) and mineral oil–chitosan emulsion (MO:CH = 25:75) as coatings on internal quality and shelf‐life of eggs were evaluated during 5‐week storage at 25 °C. Eggs with three different initial albumen qualities [Haugh unit (HU): H = 87.8, M = 75.6 and L = 70.9] were evaluated. As storage time increased, HU and yolk index values decreased whereas weight loss increased. Coating with MO and/or 25:75 MO:CH emulsion could preserve the internal quality for at least 4 more weeks for H‐eggs and at least 3 more weeks for M and/or L‐eggs, all with weight losses <0.92%. All coated eggs had >70% positive purchase intent, and their colour differences at week 0 could not be detected by naked human eye (ΔE^* < 3.0, noncoated eggs as reference). Consumers significantly differentiated freshly MO‐coated from noncoated eggs on overall surface appearance. This study demonstrated that MO and 25:75 MO:CH emulsion coatings could preserve internal quality and prolong shelf‐life of eggs.     

Edible coating affects physico‐functional properties and shelf life of chicken eggs during refrigerated and room temperature storage

Effects of chitosan, whey protein concentrate (WPC), mineral oil (MO) and/or soybean oil (SO) coating on egg quality were compared at 25 and 4 °C, respectively, during 5 and 20 weeks of storage. Storage time and temperature, and type of coating significantly affected Haugh unit, yolk index, weight loss, albumen pH and emulsifying capacity. Shelf life was extended 4 weeks by MO and SO and 2 weeks by chitosan and WPC longer than that observed for noncoated eggs at 25 °C. MO‐ and SO‐coated eggs maintained AA grade for 20 weeks at 4 °C. Weight loss of SO‐coated eggs was <1% after 5 weeks at 25 °C and after 20 weeks at 4 °C. Yolk index and emulsifying capacity were more correlated at 25 °C than at 4 °C. MO and SO were more effective coating materials, with SO providing a more cost‐effective coating for extending egg shelf life.     

Mineral oil-chitosan emulsion coatings affect quality and shelf-life of coated eggs during refrigerated and room temperature storage

Effects of mineral oil (MO) and 4 emulsions (prepared with different emulsifier types) of MO and chitosan solution (CH) at a fixed ratio of MO:CH = 25:75 as coating materials in preserving the internal quality of eggs were evaluated during 5 wk at 25 °C and 20 wk at 4 °C. Generally, as storage time increased, Haugh unit and yolk index values decreased whereas weight loss increased. However, MO and/or 4 emulsion coatings minimized the weight loss (<1.5%) and preserved the albumen and yolk quality of eggs (with the final B grade) for at least 3 wk longer than those observed for noncoated eggs at 25 °C. At 4 °C, all coated eggs changed from AA to A grade after 5 wk and they maintained this grade for 10 wk (5 wk longer than that of noncoated eggs). Although refrigeration (4 °C) alone could maintain the B grade of noncoated eggs for up to 20 wk, coating treatments were necessary to keep the weight loss below 2%. Compared with 4 °C, the increasing weight loss showed stronger negative correlation (P < 0.01) with the decreasing Haugh unit (-0.46 to -0.89) and yolk index (-0.36 to -0.89) at 25 °C. The emulsifier type used in this study generally did not affect the internal quality of eggs. Salmonella spp. detection was negative for all coated and noncoated eggs. This study demonstrated that MO and MO:CH emulsion coatings preserved the internal quality, prolonged the shelf-life, and minimized weight loss (<2%) of eggs.     

Viscosity changes of chitosan solution affect physico-functional properties and consumer perception of coated eggs during storage

Effects of storage of chitosan (CH) solution on physico-functional properties and consumer perception of CH-coated eggs were evaluated during 5- and 15-weeks storage at 25 °C and 4 °C, respectively. Seven treatments [CH0 (freshly-prepared), CH1 (stored for 1-week at 25 °C), CH1R (1-week, 4 °C), CH3 (3-weeks, 25 °C), CH3R (3-weeks, 4 °C), CH5 (5-weeks, 25 °C), CH5R (5-weeks, 4 °C)] were applied on eggshell. After 5-weeks storage, CH-solution viscosity decreased by 2.56 and 4.6 times, respectively, at 4 °C and 25 °C while pH slightly increased. CH0 preserved grade-A quality for 4-weeks vs. 1-week for noncoated eggs at 25 °C. After 5-weeks, weight loss (%) of coated eggs at 25 °C (6.04–5.59) was lower than that of noncoated eggs (7.44) but higher than that of all eggs at 4 °C (2.93–2.46). Albumen pH increased while emulsion capacity decreased with increased storage time; however, both were insignificantly affected by CH viscosity. Consumers perceived CH0- and CH1R-eggshell to be glossier than noncoated eggs after 5-weeks. Purchase intent was higher for CH-coated eggs (72–77.3%) than for noncoated eggs (61.3%). Overall, viscosity changes of CH-coating solution had lesser impact on quality of CH-coated eggs than did storage temperature/time of eggs.     

Preparation of Recombined Milk Using Modified Butterfats Containing α‐Linolenic Acid

Abstract: Modified butterfats (MBFs) were produced by lipase‐catalyzed interesterification with 2 substrate blends (6:6:8 and 4:6:10, by weight) of anhydrous butterfat (ABF), palm stearin, and flaxseed oil in a stirred‐batch type reactor after short path distillation. The 6:6:8 and 4:6:10 MBF contained 21.7% and 26.5%α‐linolenic acid, respectively. Total saturated fatty acids of the MBFs ranged from 41.4% to 47.4%. The cholesterol contents of the 6:6:8 and 4:6:10 MBFs were 21.0 and 12.1 mg/100 g, respectively. In addition, the melting points of the 6:6:8 and 4:6:10 MBFs were 32 °C and 31 °C, respectively. After preparation of recombined milks (oil‐in‐water emulsions) with MBFs, the stability of emulsions prepared with the MBFs (6:6:8 and 4:6:10) was compared to those with ABF during 10‐d storage at 30 °C. Skim milk powder (containing 1% protein) was added to prepare emulsions as an emulsifier. Microstructures of emulsions freshly prepared with the ABF and the MBFs consisted of uniform fat globules with no flocculation during 10‐d storage. With respect to fat globule size distribution, the volume‐surface mean droplet diameter (d₃₂) of the 6:6:8 and 4:6:10 MBF emulsions ranged between 0.33 and 0.34 μm, which was similar to the distribution in ABF emulsion. Practical Application: Milk, an expensive dairy food, has been widely used in various milk‐derived food products. Modified butterfats (MBFs) contain α‐linolenic acid as an essential fatty acid. Emulsion stability of recombined milks (oil‐in‐water emulsions) with MBFs was similar to that in anhydrous butterfat emulsion during 10‐d storage. They may be a promising alternative for reconstituted milks to use in processed milk‐based products.     

In vitro β‐Carotene Bioaccessibility and Lipid Digestion in Emulsions: Influence of Pectin Type and Degree of Methyl‐Esterification

Citrus pectin (CP) and sugar beet pectin (SBP) were demethoxylated and fully characterized in terms of pectin properties in order to investigate the influence of the pectin degree of methyl‐esterification (DM) and the pectin type on the in vitro β‐carotene bioaccessibility and lipid digestion in emulsions. For the CP based emulsions containing β‐carotene enriched oil, water and pectin, the β‐carotene bioaccessibility, and lipid digestion were higher in the emulsions with pectin with a higher DM (57%; “CP57 emulsion”) compared to the emulsions with pectin with a lower DM (30%; “CP30 emulsion”) showing that the DM plays an important role. In contrast, in SBP‐based emulsions, nor β‐carotene bioaccessibility nor lipid digestion were dependent on pectin DM. Probably here, other pectin properties are more important factors. It was observed that β‐carotene bioaccessibility and lipid digestion were lower in the CP30 emulsion in comparison with the CP57, SBP32, and SBP58 emulsions. However, the β‐carotene bioaccessibility of CP57 emulsion was similar to that of the SBP emulsions, whereas the lipid digestion was not. It seems that pectin type and pectin DM (in case of CP) are determining which components can be incorporated into micelles. Because carotenoids and lipids have different structures and polarities, their incorporation may be different. This knowledge can be used to engineer targeted (digestive) functionalities in food products. If both high β‐carotene bioaccessibility and high lipid digestion are targeted, SBP emulsions are the best options. The CP57 emulsion can be chosen if high β‐carotene bioaccessibility but lower lipid digestion is desired.     

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.     

Effects of Green Tea Extract and α‐Tocopherol on the Lipid Oxidation Rate of Omega‐3 Oils,Incorporated into Table Spreads,Prepared using Multiple Emulsion Technology

Abstract: This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)‐3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil‐in‐water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil‐in‐water‐in‐oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α‐Tocopherol), or both. Spreads containing α‐Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5 °C, while p‐Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G′ values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05). Practical Application: Lipid oxidation is a major problem in omega‐3 rich oils, and can cause off‐odors and off‐flavors. Double emulsion technology was used to produce omega‐3 enriched spreads (O/W/O emulsions), wherein the omega‐3 oil was incorporated into the inner oil phase, to protect it from lipid oxidation. Antioxidants were added to further protect the spreads by reducing lipid oxidation. Spreads produced had good oxidative stability and possessed functional (omega‐3 addition) properties.     

Effects of mineral oil coating on internal quality of chicken eggs under refrigerated storage

The selected internal qualities (weight loss, Haugh unit, yolk index, and albumen pH) of noncoated and mineral oil‐coated chicken eggs during 15 weeks of storage at 4 °C and/or during 5 weeks of storage at 25 °C were evaluated. Results indicated that, without refrigeration, the noncoated and mineral oil‐coated eggs rapidly changed from AA to C and B grades as measured by Haugh unit, respectively, after 5 weeks of storage. However, the AA quality of the noncoated eggs could be maintained under refrigerated storage (4 °C) for at least 5 weeks. The mineral oil coating and refrigerated storage (4 °C) synergistically minimised weight loss and preserved the albumen and yolk qualities of chicken eggs during a long‐term storage. At 4 °C, the mineral oil‐coated eggs preserved the initial AA grade for at least 15 weeks with l.19% weight loss.     

Formation of oil‐in‐water (O/W) pickering emulsions via complexation between β‐cyclodextrin and selected organic solvents

Cyclodextrins (CDs) are cyclic oligosaccharides derived from the enzymatic degradation of starch. Emulsifying functionality of β‐cyclodextrin (β‐CD) upon its complexation with selected solvents (octanol, decane, and toluene) was studied. In several tests, the three‐phase systems containing the emulsion fraction in the middle position were obtained. The examination of variations in the phase behavior of the test systems showed that the decane/β‐CD/water system had the highest emulsion phase volume when β‐CD at concentration of 10% w/v was used. A reduction in interfacial tension (IFT) of the oil–water interface in each test system was observed with the following order: toluene, decane, and octanol. The precipitated fraction obtained upon centrifugation of the emulsion phase, was structurally characterized as the inclusion complex (IC) formed between β‐CD and each of the three test solvents. The wettability of the IC particles was determined through contact angle measurement and formation of the oil‐in‐water (O/W) Pickering emulsions was confirmed (θ_ow<90°). With use of size distribution data, the ICs particles as the microparticles (1–10 µm) were found to be the main species involved in the formation and stabilization of the emulsions.     

Emulsifying Properties of Legume Proteins Compared to β‐Lactoglobulin and Tween 20 and the Volatile Release from Oil‐in‐Water Emulsions

The emulsifying properties of plant legume protein isolates (soy, pea, and lupin) were compared to a milk whey protein, β‐lactoglobulin (β‐lg), and a nonionic surfactant (Tween 20). The protein fractional composition was characterized using sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis. The following emulsion properties were measured: particle diameter, shear surface ζ‐potential, interfacial tension (IT), and creaming velocity. The effect of protein preheat treatment (90 °C for 10 min) on the emulsifying behavior and the release of selected volatile organic compounds (VOCs) from emulsions under oral conditions was also investigated in real time using proton transfer reaction‐mass spectrometry. The legume proteins showed comparable results to β‐lg and Tween 20, forming stable, negatively charged emulsions with particle diameter d_3,2 < 0.4 μm, and maintained stability over 50 d. The relatively lower stability of lupin emulsions was significantly correlated with the low protein surface hydrophobicity and IT of the emulsion. After heating the proteins, the droplet size of pea and lupin emulsions decreased. The VOC release profile was similar between the protein‐stabilized emulsions, and greater retention was observed for Tween 20‐stabilized emulsions. This study demonstrates the potential application of legume proteins as alternative emulsifiers to milk proteins in emulsion products.     

Physicochemical properties and emulsion stabilization of rice dreg glutelin conjugated with κ‐carrageenan through Maillard reaction

BACKGROUND: Rice dreg is an underutilized source of cereal protein with good potential for application in the food industry. Glutelin represents about 850 g kg^?1 of total storage protein in rice dreg. The objective of this study was to characterize the physicochemical properties and emulsion stabilization of the Maillard type conjugate formed with rice dreg glutelin (RDG) and κ‐carrageenan (1:2 weight ratio) dry‐heated at 60 °C and 79% relative humidity for 24 h. RESULTS: Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and Fourier transform‐infrared analysis provided evidence on the formation of the Maillard type conjugation. Amino acid analysis suggested that the major locus during the Maillard reaction were lysine and arginine. Circular dichroism spectra showed decreasing amounts of α‐helix and β‐strand in the products with increment in the amount of turns and random coil. Conjugation with κ‐carrageenan could significantly improve solubility of RDG (P < 0.05). Measurements of mean droplet size and creaming stability in oil‐in‐water emulsions showed that the conjugate was more effective at stabilizing emulsions at low pH or in the presence of high ionic strength. CONCLUSION: The Maillard reaction can be successfully used as a coupling method for RDG and κ‐carrageenan to form the conjugate with improved solubility and emulsion stabilization. Copyright © 2012 Society of Chemical Industry     

Phytosterols in banana (Musa spp.) flower inhibit α‐glucosidase and α‐amylase hydrolysations and glycation reaction

Three phytosterols were isolated from Musa spp. flowers for evaluating their capabilities in inhibiting glucosidase and amylase activities and glycation of protein and sugar. The three phytosterols were identified as β‐sitosterol (PS1), 31‐norcyclolaudenone (PS2) and (24R)‐4α, 14α, 4‐trimethyl‐5α‐cholesta‐8, 25(27)‐dien‐3β‐ol (PS3). IC₅₀ values (the concentration of inhibiting 50% of enzyme activity) of PS1, PS2 and PS3 against α‐glucosidase were 283.67, 11.33 and 43.10 μg mL^?1, respectively. For inhibition of α‐amylase, the IC₅₀ values of PS1, PS2 and PS3 were 52.55, 76.25 and 532.02 μg mL^?1, respectively. PS1 was an uncompetitive inhibitor against α‐amylase with K_m at 5.51 μg mL^?1, while PS2 and PS3 exhibited a mixed‐type inhibition with K_m at 52.36 and 2.49 μg mL^?1, respectively. PS1 and PS2 also significantly inhibited the formation of advanced glycation end products (AGEs) in a BSA–fructose model. The results suggest that banana flower could possess the capability in prevention of the diseases associated with abnormal blood sugar and AGEs levels, such as diabetes.     

Quality of eggs coated with oil–chitosan emulsion: Combined effects of emulsifier types,initial albumen quality,and storage

Effects of mineral oil:chitosan (MO:CH at 25:75) emulsions prepared with four different emulsifiers (2 water- and 2 oil-miscible) as coatings on the internal quality (weight loss, Haugh unit, yolk index, and albumen pH) of coated eggs were evaluated during 5 weeks at 25 ± 2 °C and 20 weeks at 4 ± 2 °C. Eggs with two initial albumen qualities [Haugh unit (HU): H = 87.8 and L = 70.9] were used. At 25 ± 2 °C, Haugh unit, yolk index, and albumen pH of all coated eggs decreased with increased storage time. Coated H- and L-eggs maintained an A-grade up to 4 weeks and 1 week, respectively. Weight loss of all coated eggs remained below 1.35% after 5 weeks of storage at 25 ± 2 °C. All coated eggs maintained an A-grade with less than 2.5% weight loss during 20 weeks of storage at 4 ± 2 °C. Emulsifier types marginally affected the internal quality of coated eggs regardless of storage temperatures.     

Selected Quality and Shelf Life of Eggs Coated with Mineral Oil with Different Viscosities

ABSTRACT:  Selected quality and shelf life of eggs coated with mineral oil having 6 different viscosities (7, 11, 14, 18, 22, and 26 cP) were evaluated during 5 wk of storage at 25 °C. As the storage time increased, weight loss and albumen pH increased whereas Haugh unit and yolk index values decreased. After 5 wk of storage, eggs coated with 11, 14, 18, 22, or 26 cP oil possessed better quality than the control noncoated eggs and eggs coated with 7 cP oil. Oil coating, irrespective of viscosities, did not improve the emulsion capacity. There was an observable trend that coating with 26 cP oil was more effective in preventing weight loss and in maintaining the Haugh unit of eggs compared with coating with other viscosities of mineral oil. Based on the Haugh unit, the grade of noncoated eggs changed from "AA" at 0 wk to "C" after 3 wk whereas that of 26 cP oil-coated eggs from "AA" at 0 wk to "A" at 3 wk and "B" at 5 wk of storage. Coating with 26 cP oil reduced the weight loss of eggs by more than 10 times (0.85% compared with 8.78%) and extended the shelf life of eggs by at least 3 more weeks compared with the noncoated eggs.     

Screening of β‐Glucosidase and β‐Xylosidase Activities in Four Non‐Saccharomyces Yeast Isolates

The finding of new isolates of non‐Saccharomyces yeasts, showing beneficial enzymes (such as β‐glucosidase and β‐xylosidase), can contribute to the production of quality wines. In a selection and characterization program, we have studied 114 isolates of non‐Saccharomyces yeasts. Four isolates were selected because of their both high β‐glucosidase and β‐xylosidase activities. The ribosomal D1/D2 regions were sequenced to identify them as Pichia membranifaciens Pm7, Hanseniaspora vineae Hv3, H. uvarum Hu8, and Wickerhamomyces anomalus Wa1. The induction process was optimized to be carried on YNB‐medium supplemented with 4% xylan, inoculated with 106 cfu/mL and incubated 48 h at 28 °C without agitation. Most of the strains had a pH optimum of 5.0 to 6.0 for both the β‐glucosidase and β‐xylosidase activities. The effect of sugars was different for each isolate and activity. Each isolate showed a characteristic set of inhibition, enhancement or null effect for β‐glucosidase and β‐xylosidase. The volatile compounds liberated from wine incubated with each of the 4 yeasts were also studied, showing an overall terpene increase (1.1 to 1.3‐folds) when wines were treated with non‐Saccharomyces isolates. In detail, terpineol, 4‐vinyl‐phenol and 2‐methoxy‐4‐vinylphenol increased after the addition of Hanseniaspora isolates. Wines treated with Hanseniaspora, Wickerhamomyces, or Pichia produced more 2‐phenyl ethanol than those inoculated with other yeasts.     

Efficacy of Antimicrobial Pullulan‐Based Coating to Improve Internal Quality and Shelf‐Life of Chicken Eggs During Storage

There has been a growing interest in the use of natural materials as a delivery mechanism for antimicrobials and coatings in foods. The aim of the present study was to evaluate the effectiveness of pullulan coatings to improve internal quality and shelf‐life of fresh eggs during 10 wk of storage at 25 and 4 °C. Three treatments of eggs were evaluated as follows; non‐coated (control; C), coated with pullulan (P), and coated with pullulan containing nisin (N). The effects of the pullulan coatings on microbiological qualities, physical properties, and freshness parameters were investigated and compared with non‐coated eggs. For non‐coated eggs, as storage time increased, yolk index, albumen index, and Haugh unit value decreased and weight loss increased. However, pullulan coatings (P or N) minimized weight loss (<1.5%) and preserved the albumen and yolk quality of eggs (with a final B grade) 3 wk longer than non‐coated eggs at 25 °C. At 4 °C, both P‐ and N‐coated eggs went from AA to A grade after 9 wk and maintained the grade for 10 wk (4 wk longer than that of non‐coated eggs). This study is the first to demonstrate that pullulan coatings can preserve the internal quality, prolong the shelf‐life, and minimize weight loss of fresh eggs.