Search

Effects of starch formulation, highly concentrated sucrose solution, and coconut milk on the stability of starch gels kept under chilled and frozen conditions were determined. Gels containing rice starch (RS), tapioca starch (TS) (RS:TS of 1 : 0.85), and hydroxypropyl distarch phosphate (HDP, 0-50% of total starch) were prepared from 15% starch suspension using water, 45°Brix sucrose syrup or coconut milk as liquid media. After aging at 4°C for 21 days, starch gels had higher hardness and chewiness, with lower cohesiveness and springiness ( p ≤ 0.05 ). Water-based gels containing HDP had less extent of texture hardening, lower degree of crystallinity, and more homogeneous microstructure during 4°C aging. However, for the starch gels in sucrose syrup or coconut milk, HDP induced greater gel hardening, higher degree of crystallinity, and denser gel microstructure during chilled storage. This could be due to the crystallization of sucrose or lipid/amylose-lipid complexes. Nevertheless, HDP enhanced freeze-thaw stability of the gels, regardless of the liquid media used ( p ≤ 0.05 ). According to the consumer test of the model desserts subjected to a single freeze-thaw cycle, the sample containing 50% HDP gel in sucrose syrup or 25% HDP gel in coconut milk gained the highest hedonic score of texture and overall acceptance ( p ≤ 0.05 ).

Synthesis of large-ring cyclodextrins (LR-CDs) in any significant amount has been challenging. This study enhanced the LR-CDs production by Thermus filiformis amylomaltase (TfAM) enzyme by starch pretreatment using glycogen debranching enzyme from Corynebacterium glutamicum (CgGDE). CgGDE pretreated tapioca starch gave LR-CD conversion of 31.2 ± 2.2%, compared with LR-CDs produced from non-treated tapioca starch (16.0 ± 2.4%). CgGDE pretreatment enhanced amylose content by approximately 30%. Notably, a shorter incubation time of 1 h is sufficient for CgGDE starch pretreatment to produce high LR-CD yield, compared with 6 h required for the commercial isoamylase. High-Performance Anion Exchange Chromatography coupled with Pulsed Amperometric Detection (HPAEC-PAD) and Gel Permeable Chromatography (GPC) revealed that CgGDE is more efficient than the commercial isoamylase in debranching tapioca starch and gave lower molecular weight products. In addition, lower amount of by-products (linear oligosaccharides) were detected in cyclization reaction when using CgGDE-pretreated starch. In conclusion, CgGDE is a highly effective enzyme to promote LR-CD synthesis from starch with a shorter incubation time than the commercial isoamylase.

Variations in starch pasting properties, considered an alternative potential quality classification parameter for rice starches, are directly controlled by the diverse starch molecular composition and structural features. Here, the starch characteristics of four rice cultivars (i.e., RD57, RD29, KDML105, and RD6) differing in pasting properties were assessed, and their relationship was determined. The results revealed that protein and moisture contents and their crystalline type were similar among the four rice starches. However, their molecular compositions and structures (i.e., reducing sugar and amylose contents, amylopectin branch chain-length distributions, granule size and size distribution, and degree of crystallinity) significantly varied among different genotypes, which resulted in distinct swelling, solubility, gelatinization, retrogradation, and hydrolytic resistance properties. The swelling power and gelatinization enthalpy (∆H) were positively correlated with C-type granule and relative crystallinity, but were negatively correlated with amylose content, B-type granule and median particle size (d(0.5)). Conversely, the water solubility and resistant starch content negatively correlated with C-type granule, but positively correlated with amylose content, B-type granule, and d(0.5). The gelatinization onset temperature (To(g)), and retrogradation concluding temperatures (Tc(r)), enthalpy (∆H(r)), and percentage (R%) were positively impacted by the amount of protein, amylose, and B1 chains (DP 13–24), while they were negatively correlated with short A chains (DP 6–12). Collectively, the starch physicochemical and functional properties of these Thai rice starches are attributed to an interplay between compositional and structural features. These results provide decisive and crucial information on rice cultivars’ suitability for consumption as cooked rice and for specific industrial applications.

In-depth molecular structure and properties of cassava-derived resistant maltodextrins (RMDs) were determined. Cassava starch was dextrinized with 0.04% or 0.06% HCl at 120 °C for 60–180 min to obtain resistant dextrins (RDs), which were further hydrolyzed by α-amylase to produce RMDs. Prolonging dextrinization duration decreased proportion of α-1,4 linkages and α-/β-reducing ends but increased fraction of indigestible α-/β-1,6, β-1,4, β-1,2 linkages, degree of branching (DB), degree of polymerization, relative molecular weight, and total dietary fiber (TDF) content of the RMDs. Moreover, RMDs had greater proportion of β-glycosidic linkages, α-/β-reducing end, DB, TDF, and low molecular weight dietary fiber (LMWDF) content than their RD counterparts. Potential prebiotic activity score was higher in RMDs with abundant LMWDF fraction but low DB. Slight difference in the glass transition temperature of maximally freeze-concentrated unfrozen phase (Tg’) and unfrozen water content was found among RMDs. However, RMDs had lower Tg’ than their RD counterparts.

The water solubility of domperidone (DMP) could be improved by complexation with large ring cyclodextrins (LR-CDs). LR-CDs contain a relatively hydrophobic cavity that is capable of entrapping the molecules to form inclusion complexes. The complex formation capability of mixture LR-CDs having a degree of polymerization (DP) of 22–48, with DMP was investigated. The phase solubility profile of mixture LR-CD/DMP was classified as AN-type, resulting in increased DMP solubility in water by 3-fold. Various physicochemical techniques confirmed the mixture LR-CD/DMP complex formation. Single LR-CD with DP of 26, 27, 28, 29, 30, 33 and 34 (CD26 ~ CD34) were isolated from LR-CD mixtures using ODS column for HPLC separation. The CD33/DMP complex has demonstrated the most significant improvement compared to other single LR-CD complexes with a 2.7-fold increase in DMP solubility. The molecular dynamic result revealed that DMP formed stable complexes with CD33 by positioned fully encapsulated inside the cavity and covered by 13–14 subunits of CD33.

Impact of drying process and storage conditions on properties of konjac glucomannan (KGM) and whey protein isolate (WPI) blend films was investigated. Hundred grams of film solution contained 0.4 g KGM, 3.8 g WPI and 1.5 g glycerol. During drying process, air velocity was varied to produce fast drying (3 h) and slow drying (15 h) in tray dryers under 50 °C. The high air velocity resulted in a significant higher drying rate in fast drying than low air velocity in slow drying. Drying curves from both processes were well-fitted with Page model and Henderson and Pabis model (R2 ≥ 0.98). Fast drying improved transparency and mechanical properties without impairing color, solubility or water vapor permeability (WVP). Fast-dried film had less surface roughness and contained larger protein clusters. It also had greater melting enthalpy of protein aggregates, implying stronger networks. For stability study, fast-dried film was stored at 4-35 °C for 24 days. Transparency decreased over time. Overall mechanical properties have improved during storage. Color, solubility and WVP did not significantly change over time at all conditions (p > 0.05). Microstructure of aged films was relatively similar to that of the freshly prepared film. Overall, the fast-dried KGM-WPI film exhibited reasonable storage stability.

Effects of packaging materials (metalized or polylactic acid, PLA, based pouches), storage temperatures (30-50°C) and time (up to 6 months) on quality of solar-dried banana were investigated. At 30°C in both packaging materials, change in moisture content, water activity (a w ) and hardness were minimal while darkening of the surface color progressed. No microbial spoilage was found. Hedonic scores of color, flavor, taste, texture and overall acceptance of the 6th month aged samples were lowest (p≤0.05). Based on the sensory test, product packed in both packaging materials had shelf life of 5 months at 30°C. Higher storage temperature greatly induced time-dependent decrease in moisture content and a w with an increase in hardness, especially for the samples in PLA-based pouches. Fractional conversion model was used to predicted time-dependent change in total color difference (ΔE) (R2 ≥ 0.84). Temperature dependence of the rate constant followed Arrhenius-type relationship (R2 ≥ 0.99).

Background The use of biodegradable polymeric materials has been proposed as an environmentally-friendly alternative to petroleum-based packaging. To extend the shelf life of food products, these bioplastics must possess appropriate barrier properties and food-package stability. In the present study, shelf life analysis of packaged baby formula in biopolymeric, multilayer film, fabricated from poly(lactide) (PLA) and whey protein isolate (WPI), PLA/WPI/PLA and PLA pouches was performed at 4-35 o C and 50-59% relative humidity. Results Despite the possible sorption of food components into contact PLA surfaces, the results demonstated that the transparency and barrier properties of PLA-based pouches were insignificantly changed over time (P > 0.05), although the films showed a slow rate of color change. The baby formula packaged in PLA/WPI/PLA had a delayed lipid oxidation compared to the sample in the PLA pouch, especially at a higher temperature. The application of WPI in the multilayer structure shifted the shelf life determination factor from lipid oxidation to moisture gain. Conclusion The results indicate that the PLA/WPI/PLA pouch has good storage stability. The film could be used to package dry food properly at 4-35 o C and 50-59% relative humidity for an extended period of time. © 2016 Society of Chemical Industry.

The objectives of this study were to monitor the changes in rice properties during aging and to compare kinetic parameters related to some of those changes. Paddy of three low amylose rice varieties was stored at ambient (30 ± 2oC) and chilled (8 ± 2oC) temperatures for 9 and 18 months, respectively. Aging led to a decrease in solid loss, peak viscosity, breakdown, and adhesiveness and an increase in head rice yield, minimum cooking time, water uptake, volume expansion, pasting temperature, final viscosity, through viscosity, setback, and hardness. Low temperature storage efficiently retarded those changes. Data of the time-dependent changes in hardness, adhesiveness, pasting temperature, peak viscosity, and breakdown of all samples stored at 30°C were fitted well with the first-order fractional conversion kinetic model (R2 = 0.77 – 0.98). Higher storage temperature resulted in greater rate constant (k; up to 9 times higher) of those changes.

To extend the shelf life of sponge cake by an O 2 scavenger (OS) and an ethanol emitter (EE) as alternatives to chemical preservatives, sponge cake samples were packaged with an active packaging system and a high barrier pouch, polyvinylidene chloride (PVDC)-coated nylon or nylon. Effects studied included the initial rate of O 2 reduction, total O 2 -scavenging capacity to maintain critically low O 2 concentration through storage, and effects of ethanol on microbial growth and evolution of headspace CO 2 and O 2 . Active packaging system effectively extended mold-free shelf life of preservative-free cake from ∼1 day (control) to more than 42 days. By significantly retarding microbial growth and activities, active packaging shifts the critical shelf life determination reaction to physicochemical deteriorations. OS retarded lipid oxidation and enhanced color stability of the cake. EE delayed staling. PVDC-coated nylon enhanced the efficiency of active packaging better than nylon. The combination of OS and EE synergistically delayed microbial spoilage as well as physical and chemical deteriorations. Application of active packaging systems is an effective alternative preservation technology for prolonging the shelf life of highly perishable sponge cake without the direct addition of chemical preservatives into the bakery formula.

The impact of spice powders on physical, mechanical, thermal and barrier properties, and on storage stability, of whey protein isolate (WPI)-based films was determined. Films with added spices were prepared from casting solution containing 10 % (w/w) heat-denatured WPI, glycerol (WPI:glycerol of 3:2 w/w), sodium chloride (0.4 g/100 g solution), garlic and pepper powders (≤3 g each/100 g solution). Water activity (aw) of all films was 0.53–0.57. Addition of spice powders increased thickness, darkness and yellowness of the WPI films. Films with added spices had lower tensile strength (TS), percent elongation (%E), and melting enthalpy of WPI matrices, but possessed higher water vapor permeability (WVP) than WPI film without sodium chloride and spices. The WPI film containing highest amount of garlic powder and lowest amount of pepper powder was selected for storage tests at 25–45 °C. Storage for up to 49 days resulted in reduced aw and %E, increased TS, and color changes at 35 and 45 °C, with few changes at 25 °C. However, film WVP and OP were not affected by storage conditions after 7 days storage. Active ingredients decreased over time with up to 81 % allicin and 37 % piperine retained in the film matrix after 47 days storage.

The objective of this research was to study the changes in physicochemical properties of rice during elevated temperature storage. Paddy of three rice cultivars with low amylose content (9–11%) and the other three with high amylose content (23–25%) was stored at 39.2 °C and 43.1% relative humidity up to 31 weeks. Drastic changes in moisture content and some parameters representing cooking qualities, cooked rice texture and pasting properties occurred during the first four weeks of aging. At similar aging time, low amylose rice had higher adhesiveness, peak viscosity and breakdown, but had lower pasting temperature than high amylose rice. Time-dependent change in adhesiveness and pasting temperature was predicted by fractional conversion model (0.60 ≤ R2 ≤ 0.94). Difference among rate constant values of the data from low and high amylose rice was found. Proportion of high molecular weight proteins (>225 kDa) tended to increase over time. However, enthalpy of amylose-lipid complex melting fluctuated during storage. Changes in protein molecular weight pattern could thus be key mechanism of rice aging at elevated temperature. NIR-based predictive models for minimum cooking time, adhesiveness, pasting temperature, peak viscosity, and breakdown of rice samples were established (R2 of calibration ≥ 0.81; R2 of validation ≥ 0.87).

The objective of this research is to develop edible, fast dissolving, sealable whey protein isolate (WPI)-based films for packaging premeasured dry foods/ingredients that will dissolve and release their contents upon contact with water. Modifications to the structure and properties of WPI films via heat-denaturation and plasticizers were determined. The structure-function relationship of the films was elucidated based on FTIR analysis. The developed water-soluble native WPI (NWPI) films had similar visual and barrier properties (oxygen permeability 4.74 × 10−4 to 12.26 × 10−4 cm3 μm/m2∙s∙kPa and water vapor permeability 0.0113–0.0148 g mm/m2∙s∙kPa) but lower mechanical properties (tensile strength 1.04–3.16 MPa, % elongation 7.45–15.31%, and elastic modulus 18.88–105.34 MPa) than the water-insoluble heat-denatured WPI films. The solution-sealed NWPI pouches of dry food models showed ready solubility. Heat denaturation strengthened the cohesion of the WPI films via the enhanced formation of the intermolecular β-sheet. Glycerol and atmospheric moisture showed plasticizing effects on both the barrier and tensile properties, which correlated well with the films’ moisture sorption isotherms. Solution-sealed NWPI pouches can be potentially used as leave-in packaging for portioned dry foods. The comprehensive understanding of the properties of glycerol-plasticized WPI films gained from this study is valuable in designing WPI-based packaging for commercial packaged food systems.

Physical, chemical and thermal properties, as well as molecular structure of cassava-based resistant dextrins prepared under different dextrinization conditions (0.04–0.10% HCl, 100–120 °C, 60–180 min) were determined. Increasing acid concentration, temperature and heating time resulted in the products with darker color, higher solubility, reducing sugar content, total dietary fiber and proportion of high molecular weight fiber fraction. An endothermic peak at 45–70 °C, having enthalpy of 1.66–2.14 J/g, was found from the samples processed under mild conditions (0.04–0.08% HCl, 100 °C, 60 min). However, harsher dextrinization conditions eliminated this endotherm. Dextrinization led to 1000-fold decrease in weight-average molecular weight (Mw) of the products, comparing to the native starch. Stronger processing conditions yielded the resistant dextrins with slightly higher Mw but composing of shorter branched chains. During dextrinization, hydrolysis was a predominant step, while transglucosidation and repolymerization played key roles in modifying molecular structure and properties, especially dietary fiber content, of resistant dextrins.

This work aimed to investigate freeze thaw stability of 20 wt% coconut oil (CtO) and corn oil (CnO)-in-water emulsions stabilized by 1 wt% of various types of sucrose esters and Tweens. Sucrose esters composed mainly of sucrose monostearate (S1670), sucrose monopalmitate (P1670), sucrose monolaurate (L1695), Tween 20 (TW20), Tween 60 (TW60), and Tween 80 (TW80) were used. After all emulsions were frozen at ∼−20 ± 2 °C and thawed to room temperature, their stability was analyzed from visual appearance, optical micrographs, amounts of destabilized oil, and average particle sizes. The CtO emulsions stabilized by S1670 and P1670 were very stable, the CtO emulsions stabilized by L1695 partly destabilized, and the CtO emulsions stabilized by TW20, TW60, and TW80 mostly destabilized into oil layers separated on top. The excellent stability of CtO emulsions stabilized by S1670 and P1670 was also confirmed from similar thermograms obtained from differential scanning calorimeter after three cooling–heating cycles (40 °C to −40 °C to 40 °C at 5 °C/min). It was proposed here that S1670 and P1670 affected the interfacial fat crystallization and their interfacial layers protected CtO emulsions against partial coalescence. Differently for the case of CnO emulsions, the CnO droplets remained liquid during freezing. All CnO emulsions stabilized by any emulsifiers destabilized by coalescence since these small surfactants could not provide enough interfacial barriers.

Edible composite packaging has been developed by blending biocomponents for specific applications, aiming to take advantage of complementary functional properties or to overcome their respective flaws. The aim of this work was to study the effect of incorporation of whey protein isolate (WPI) on the properties of konjac glucomannan (KGM) based films. Five aqueous solutions of KGM and/or WPI were prepared by casting and solvent evaporation of 1:0, 0.8:3.4, 0.6:3.6, 0.4:3.8 and 0:4.2 g KGM:g WPI/100 g solution. Glycerol (Gly) was used as a plasticizer at 1.5 and 1.8 g/100 g solution. The result showed that incorporated WPI proportionally increased transparency of KGM-based films. An increase in proportion of WPI resulted in decreased tensile strength and elastic modulus as well as improved flexibility. The incorporation of WPI into the KGM matrix led to an increase in water insolubility which enhanced product integrity and water resistance. Nevertheless, WPI did not improve water vapor barrier of KGM–WPI films. WPI and blend film with the highest concentration of WPI could be heat sealed at 175 °C. Overall, the range of Gly in this study did not apparently affect properties of the films.

The stability of biopolymeric multilayer film fabricated from poly(lactide) (PLA) and glycerol-plasticized whey protein isolate (WPI), PLA/WPI/PLA, at 4 °C, 25 °C, and 35 °C were examined. The PLA/WPI/PLA film showed small rates of decreasing in transparency and increasing total color difference. Storage at 35 °C caused the film to become stronger and less extendible. The multilayer structures showed lower tensile strength and higher elongation over storage at 4 °C and 25 °C. Oxygen and water vapor barrier abilities of PLA/WPI/PLA gradually improved over time, especially at 35 °C. The changes in properties of laminate structure can be empirically fitted with either zero- or first-order reaction kinetics, with overall R2 ≥ 0.90. The results suggested that PLA/WPI/PLA film could be stored at 4–35 °C, 50–59% RH, for extended period of inventory time. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43547.

Summary Influences of the conditions of raw rice storage and cooking on parameters related to colour and antioxidant activities of organic hulled red fragrant rice were investigated. Raw rice samples were vacuum-packed in oriented polypropylene/aluminium/linear low-density polyethylene or nylon/linear low-density polyethylene pouches and stored at ambient temperature or 15 °C up to 12 months. Cooked samples were prepared from aged raw samples. Kernel colour, total anthocyanin content (TAC) of acidic methanolic extracts as well as total phenolic content (TPC), reducing power (RP) and radical scavenging activity (RSA) of methanolic extracts and enzymatically digested samples were maintained during 12-month storage, regardless of packaging materials and storage temperatures. Cooked kernels had larger L value, lower a and b values, and greater TAC (dry basis), comparing with the raw rice. Cooking caused drastic decrease in TPC, RP and RSA of methanolic extracts. Nevertheless, less negative impacts of cooking were found for enzymatically digested samples.

The effects of engineering higher levels of the High Molecular Weight Glutenin Dx5 subunit on starch characteristics in transgenic wheat (Triticum aestivum L.) grain were evaluated. This is important because of the interrelationship between starch and protein accumulation in grain, the strong biotechnological interest in modulating Dx5 levels and the increasing likelihood that transgenic wheat will be commercialized in the U.S. Unintended effects of Dx5 overexpression on starch could affect wheat marketability and therefore should be examined. Two controls with native levels of Dx5 were used: (i) the nontransformed Bobwhite cultivar, and (ii) a transgenic line (Bar-D) expressing a herbicide resistant (bar) gene, and they were compared with 2 transgenic lines (Dx5G and Dx5J) containing bar and additional copies of Dx5. There were few changes between Bar-D and Dx5G compared to Bobwhite. However, Dx5J, the line with the highest Dx5 protein (×3.5) accumulated 140% more hexose, 25% less starch and the starch had a higher frequency of longer amylopectin chains. These differences were not of sufficient magnitude to influence starch functionality, because granule morphology, crystallinity, amylose-to-amylopectin ratio, and the enthalpy of starch gelatinization and the amylose–lipid complex melting were similar to the control (P > 0.05). This overall similarity was borne out by Partial Least Squares-Discriminant Function Analysis, which could not distinguish among genotypes. Collectively our data imply that higher Dx5 can affect starch accumulation and some aspects of starch molecular structure but that the starches of the Dx5 transgenic wheat lines are substantially equivalent to the controls. Practical Application: Transgenic manipulation of biochemical pathways is an effective way to enhance food sensory quality, but it can also lead to unintended effects. These spurious changes are a concern to Government Regulatory Agencies and to those Industries that market the product. In this study we examined if making “specific” changes to the composition of gluten proteins in wheat seeds would simultaneously alter starch, as their synthesis is interrelated and the molecular structure of both determine f lour functionality. This information may be used to address issues of “substantial equivalence” and to inform Industrial End-Users of possible changes in product performance.

Effects of packaging materials, storage temperatures and time on physicochemical properties of organic hulled red fragrant rice cv. Hom Daeng were investigated. The samples were vacuum-packed in oriented polypropylene/aluminium/linear low-density polyethylene or nylon/linear low-density polyethylene pouches and stored at ambient temperature or 15 °C for up to 12 months. Results from differential scanning calorimetry indicated that onset and peak temperature of gelatinisation of the aged rice samples increased after the 6th month while enthalpy of gelatinisation initially increased and then decreased after the 8th month. Measurements from the Rapid Visco Analyzer revealed that peak viscosity and breakdown of the rice pastes increased within the first 2 months, then decreased after the 6th month, whereas setback gradually increased during storage. Swelling power, at 70 and 90 °C, of the aged samples, tended to decrease after the 4th month. Lower storage temperature retarded those changes while packaging materials did not influence the changes. Changes in thermal and pasting properties of the aged samples were reversed after adding 2-mercaptoethanol. Hence, an increase in disulphide linkages of oryzenin during storage could play a crucial role in altering those properties. Sensory evaluation indicated a significant increase in hardness of the cooked rice prepared from the longer-aged samples (p ⩽ 0.05). However, the cooked rice samples, deriving from the samples stored at ambient temperature for up to 12 months, were still acceptable for Thai consumers.

BACKGROUND: Aroma of fragrant rice greatly affects palatability as well as consumer acceptability. Loss of desirable volatile compounds such as 2-acetyl-1-pyrroline (2-AP) and increase in volatile lipid oxidation products in aged rice have been reported. The aim of this study was to monitor the changes in key volatile compounds of organic red fragrant rice cv. Hom Daeng during storage. Effects of packaging material, storage temperature and time were evaluated using solid phase microextraction/gas chromatography/mass spectrometry. RESULTS: Thirteen key volatile compounds including ten lipid oxidation products were monitored. For samples vacuum packed in Nylon/LLDPE pouches at ambient temperature, significant increases in hexanal, 2-pentylfuran, 1-octanol and 4-vinyl guaiacol and significant decreases in 2-AP and geranyl acetone were found after the second month (P⩽0.05). Vacuum packing in OPP/Al/LLDPE pouches or storage at 15 °C better retarded the formation of volatile lipid oxidation products and greater retained desirable odorants, including 2-AP. However, accumulation of lipid oxidation products and 4-vinyl guaiacol was apparent after the sixth month under these storage conditions. CONCLUSION: A greater extent and higher rate of undesirable changes in volatile compounds were found in samples stored under Nylon/LLDPE/ambient temperature condition. Nevertheless, this condition is acceptable for the retail trade of organic rice in Thailand. Storage conditions using reduced temperature or better packaging materials may be more appropriate for exported rice or superior-grade fragrant rice to better maintain the desirable rice aroma. Copyright © 2010 Society of Chemical Industry

This research aimed to determine optimum extraction condition of black glutinous rice crude extract and to determine its application as an antioxidant in fish oil enriched mayonnaise. Black glutinous rice flour was extracted twice with 70:30 acetone-water mixture (v/v) at pH 2 and 6.8 for 2, 4 and 8 h of total extraction times. Total phenolic content (TPC), total monomeric anthocyanin content (TMA) and antioxidant activities as determined by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assays of the crude extracts were measured. The extraction with pH 6.8 solvent for 4 h yielded the crude extract with significantly highest antioxidant activities analyzed by both FRAP and DPPH tests (p ≤ 0.05) although its TPC and TMA were not greatest. The freeze-dried extract from this condition was then added into fish oil enriched mayonnaise at 500 mg/kg and 1000 mg/kg (oil weight basis). Conjugated diene hydroperoxides (CDH), thiobarbituric acid reactive substance (TBARs) and color in CIELAB system of the mayonnaise samples stored at 30 °C were determined up to 30 days. The samples contained 1000 mg/kg crude extract had lowest rate of CDH and TBARs increase but had greatest extent of color deterioration, possibly due to anthocyanin degradation and Maillard reaction.

The aim of this work was to determine if the molecular structure of starch from tomato ( Solanum lycopersicum L.) is influenced by fruit physiology and carbohydrate metabolism. The effect of fruit size, fruit ripening behavior, and assimilate availability on starch granule accumulation was examined in nine tomato samples. The percentage of (14)C-glucose partitioning to starch was similar among samples, but starch contents varied 10-fold, suggesting differences in metabolism. In contrast, granule size (10-20 microm), amylose content (19-23%), degree of crystallinity (26-31%), and enthalpy of gelatinization (14.8-17.2 degrees C) were similar. Some differences in structure were detected in starch from the largest and smallest fruit using more sensitive analyses such as thermal properties, chain length distribution of amylopectin, and susceptibility to in vitro alpha-amylase digestion. However, overall, our results suggest that granule characteristics are highly conserved in tomato fruit, and we conclude that this is likely due to inherent metabolic constraints.

The interactions between water and starch during gelatinization as affected by water content, maximum heating temperature and amylopectin crystallinity pattern were investigated by Differential Scanning Calorimetry (DSC) and 1H NMR relaxation. DSC was used to measure additional unfrozen water (AUW) arising from gelatinization, reflecting enhanced water–starch interactions, and enthalpy of gelatinization (ΔHgel) of waxy corn, normal corn, potato and pea starches between 0.7 and 3.0 g water/g dry starch. The contribution of separated G and M1 stages in gelatinization was estimated using a deconvolution DSC technique. The results show that AUW largely depends on the initial water content. For the samples subjected to higher heating temperature (M1 process), a larger AUW is found presumably due to the greater disruption in granule structure. Deconvolution of the biphasic endotherm suggests that, as water content increases, the M1 process is much reduced and gradually incorporates into the dominant G process. NMR T2 distribution reveals two distinct water populations corresponding to intra- and extra-granular water, which rapidly exchange during gelatinization. After the M1 process, a relatively homogeneous gel with one water fraction from fast diffusional averaging is obtained. AUW and peak T2 values of pea starch are intermediate between those of native corn and potato starches, consistent with its composite A- and B-type crystal structure.

The effects of initial water content, maximum heating temperature, amylopectin crystallinity type, and annealing on the glass transition of starch gels were studied by differential scanning calorimetry (DSC). The glass transition temperatures of the frozen gels measured as the onset (T(g,onset)) or midpoint temperature (T(g,midpoint)), heat capacity change during the glass transition (deltaC(p)), unfrozen water of starch gels, and additional unfrozen water (AUW) arising from gelatinization were reported. The results show that T(g,onset) and T(g,midpoint) of the partially gelatinized gels are independent of the initial water content, while both of the T(g) values of the fully gelatinized gel increase as the initial water content increases. These observations might result from the difference in the level of structural disruption associated with different heating conditions, resulting in different gel structures as well as different concentrations of the sub-T(g) unfrozen matrix. The amylopectin crystallinity type does not greatly affect T(g,onset) and T(g,midpoint) of the gels. Annealing at a temperature near T(g,onset) increases both T(g,onset) and T(g,midpoint) of the gels, possibly due to an increase in the extent of the freeze concentration as evidenced by a decrease in AUW. Annealing results in an increase in the deltaC(p) value of the gels, presumably due to structural relaxation. A devitrification exotherm may be related to AUW. The annealing process decreases AUW, thus also decreasing the size of the exotherm.

© 2015 American Chemical Society. The aim of this work was to examine agronomic, compositional, and functional changes in rice (Oryza sativa L. cv. Nipponbare) grains from plants grown under low-to-moderate salinity stress in the greenhouse. Plants were grown in sodium chloride-containing soil (2 or 4 dS/m2electrical conductivity), which was imposed 4-weeks after transplant (called Seedling EC2 and EC4) or after the appearance of the anthers (called Anthesis EC2 and EC4). The former simulates field conditions while the latter permits observation of the isolated effect of salt on grain filling processes. Key findings of this study are the following: (i) Plants showed adaptive responses to prolonged salt treatment with no negative effects on grain weight or fertility. Seedling EC2 plants had more panicles and enhanced caryopsis dimensions, while surprisingly, Seedling EC4 plants did not differ from the control group in the agronomic parameters measured. (ii) Grain starch increased in Seedling EC4 (32.6%) and Anthesis EC2 (39%), respectively, suggesting a stimulatory effect of salt on starch accumulation. (iii) The salinity treatment of 2 dS/m2was better tolerated at anthesis than the 4 dS/m2treatment as the latter led to reduced grain weight (28.8%) and seed fertility (19.4%) and compensatory increases in protein (20.1%) and nitrogen (19.8%) contents. (iv) Although some salinity treatments led to changes in starch content, these did not alter starch fine structure, morphology, or composition. We observed no differences in reducing sugar and amylose content or starch granule size distribution among any of the treatments. The only alterations in starch were limited to small changes in thermal properties and glucan chain distribution, which were only seen in the Anthesis EC4 treatment. This similarity of compositional and functional features was supported by multivariate analysis of all variables measured, which suggested that differences due to treatments were minimal. Overall, this study documents the specific response of rice under defined conditions, and illustrates that the plasticity of plant response to mild stress is complex and highly context-dependent, even under greenhouse conditions in which other potential environmental stress impacts are minimized.

High-pressure inactivation of Salmonella Typhimurium DMST 28913, eating quality, and microstructure of pressurized raw chicken breast meat was determined. The inoculated samples (approximately 7 log CFU/g initial load) were processed at 300 and 400 MPa, using pressurized medium of 25 to 35 °C during pressurization. Weibull model was well fitted to the survival curves with tailing. Least severe conditions with acceptable inactivation levels were 300 MPa, 35 °C, 1 min (approximately 2 log reduction) and 400 MPa, 30 °C, 1 min (approximately 4 log reduction). Based on these 2 conditions, the 400 MPa treatment yielded the raw chicken meat with higher L* value, greater cooking loss, and lower water holding capacity. Cooked chicken breast meat prepared from the pressurized samples had firmer texture than the control. Scanning electron microscopic images showed that higher pressure resulted in increasing extent of protein coagulation and the contraction of the muscle bundles. Practical Application: For raw chicken breast fillet, 300 MPa, 35 °C, 1 min was the condition that reasonably reduced the load of Salmonella Typhimurium. However, the pressurized samples had greater cooking loss. Marination with brine containing sodium chloride and phosphate prior to pressurization might help improve this eating quality.

UNLABELLED Residual O(2) in a package headspace can be removed by an O(2)-absorbing sachet, which can be harmful if swallowed by the consumer, or by a chemically-active plastic packaging film, which is difficult to recycle. An edible, O(2)-absorbing film would avoid these disadvantages. The objective of our research was to assess the O(2)-scavenging potential of an edible whey protein isolate (WPI) film incorporating ascorbic acid (AA). AA at 0.05, 0.1, or 0.2 M was added to 5% (w/w) heat-denatured WPI film-forming solutions with WPI : glycerol (Gly) ratio of 1: 1.00, 1: 0.80, or 1: 0.67. The pH of solutions was then adjusted to 3.5 (below pK(a1) of AA), to stabilize AA against oxidation, before film casting. The mechanical properties, O(2) permeabilities, and thermal transitions of films were measured. Activation of the O(2)-scavenging function of the AA-incorporated films was accomplished by adjustment of the films to pH ≥ 7. O(2)-scavenging ability of AA-incorporated WPI films was determined by measuring residual O(2) in the headspace of a high-barrier container. Incorporation of AA into WPI film decreased film tensile strength and further reduced O(2) permeability at each WPI : Gly ratio. AA-containing films adjusted to pH ≥ 7 demonstrated O(2) absorption proportional to AA content, consistent with theoretical O(2)-scavenging capacity. Thermal transition measurements indicated that AA was involved in WPI structural modification and decreased the degradation temperature of WPI-based film. The demonstrated O(2)-scavenging function, improved O(2) barrier and acceptable mechanical properties of AA-incorporated films indicate potential commercial usefulness. PRACTICAL APPLICATION Ascorbic acid-incorporated whey protein film with oxygen scavenging function can be used to extend shelf lives of a wide variety of oxygen-sensitive products by eliminating headspace oxygen as well as oxygen permeating through the packaging wall over time. Edible oxygen-scavenger film has the advantages of avoiding both accidental consumption and nonrecyclability of conventional oxygen scavenger systems.

Publisher Summary Macadamia is a tree nut indigenous to Australia, whose kernels can be processed into a wide variety of products, such as nut snacks, oil, and flours. Macadamia kernels are good sources of proteins, dietary fibers, vitamins, and minerals. Defatted or reduced-fat macadamia flours obtained as by-products of macadamia oil production can be nutrient-rich ingredients for foods and beverages. This chapter provides a review of the production and nutritional quality of macadamia nuts and flours. Details on functional aspects as well as possible applications of macadamia flours in food products are also provided. A limited amount of lysine is a significant problem in using macadamia flours as potential protein sources. A limited amount of lysine is a significant problem in using macadamia flours as potential protein sources. Mixtures of macadamia flours and other lysine-rich flours are thus recommended as ingredients for protein fortification in baked goods. A higher degree of lipid extraction improves functional properties, including water and oil absorption capacities and foaming capacity, of macadamia flours. Due to their outstanding functional properties, macadamia flours may be used to replace egg and dairy ingredients, as well as to enhance the texture and flavor of baked goods.

The objective of this research was to study the chemical compositions, functional properties, and microstructure of partially defatted flours (PDF, 12–15% fat, dry basis (db)) and totally defatted flours (TDF, 1% db fat) from three macadamia cultivars, PY 741, DS 344, and DS 800, grown in Northern Thailand. The defatted flours were high in protein (30.40–36.45% db) and carbohydrate (49.29–57.09% db). For each macadamia cultivar, while emulsion activities and emulsion stabilities of the TDF tended not to be different from those of the PDF ( p > 0.05), TDF had significantly greater water absorption capacities (WAC), oil absorption capacities and foaming capacities (FC), but had significantly lower foaming stability (FS) than the PDF ( p ⩽ 0.05). The TDF from PY 741 cultivar possessed the highest WAC and FC but the lowest FS. The variation in the functional properties of the defatted flours could mainly arise from the difference in the quantity and characteristics of the proteins in the flours. Structure determination of macadamia flours showed that the proteins bodies and starch granules were embedded in kernel tissues. The starch granules were oval and approximately 10 μm in diameter.