教学课程资源库 更多>>

关键词： Antioxidant capacity   flavanols   food safety   Malus domestica   total phenolics  

摘要： Providing consumers with fresh and safe fruit can greatly increase their access to recommended daily intake of phytonutrients. Thus, this study investigated the impact of dipping in alkaline electrolyzed water (AEW) and dipping duration on the physicochemical, phytonutrients and microbial load on 'Granny Smith' apples. Apples treated with AEW (200 and 300 mg L-1) were compared to sodium hypochlorite (NaOCl, 200 mg L-1) and to non-treated (control) under dipping durations of 10 and 15 min. Apples treated with AEW maintained titratable acidity (TA) and total soluble solids (TSS) compared to other treatments (P > 0.05). Interaction of treatments and storage duration had a significant impact (P <= 0.05) on total phenolics and flavonoids contents. Apples treated with AEW better maintained antioxidant capacity compared to control. Treatments with AEW resulted in approximate to 2 Log reduction in total aerobic mesophilic bacteria (4.1 Log CFU cm(-2) to 2.2 Log CFU cm(-2)) and < 1 Log reduction for yeasts and moulds (3.9 Log CFU cm(-2) to 2.7 Log CFU cm(-2)). This study demonstrated the efficacy of electrolyzed water treatment as an alternative to conventional pack-house practices for apple fruit.

关键词： Breakfast cereal   calcium carbonate   extrusion   lecithin   silkworm pupae powder  

摘要： Effects of Lecithin (LC):Calcium carbonate (CaCO3) ratios (0.00:0.50, 0.10:0.40, 0.25:0.25, 0.40:0.10 and 0.50:0.00%w/w) on selected physicochemical properties and sensory acceptability of extruded breakfast cereals made with silkworm (Samia ricini D.) pupae powder and rice flour were investigated. The control sample was made without LC:CaCO3. Compared to the control, addition of LC significantly (P <= 0.05) reduced sectional expansion index, water solubility index and hardness, while increasing L*, bulk density and water absorption index of the samples. Increasing the CaCO3 level decreased bulk density while increased L*, Delta E*, sectional expansion index and crispness. The LC:CaCO3 interaction influenced a(w), moisture, porosity and sensory liking, especially at 0.10:0.40%w/w which was suitable to produce the breakfast cereals. All samples had a protein content between 31.70% and 33.76% (dry basis), which made them qualified as a "high-protein" source. The white malt-honey flavour coating increased liking scores of the finished product compared to the uncoated ones.

关键词： Starch   X-ray diffraction   Scanning electron microscopy   Second harmonic generation microscopy   Fourier transform infrared spectroscopy   Differential scanning calorimeter  

摘要： Starch from a given botanical source can vary considerably in terms of physicochemical properties in its native and hydrolyzed forms. The current study investigated the structural and functional characteristics of starch from ten indigenous rice varieties endemic to Northeast India. In vitro enzymatic hydrolysis was used to reveal the dextrose equivalent profile of each type of starch. Gezep Sali and Betguti Sali respectively exhibited the highest and lowest starch hydrolysis. Among the ten rice varieties, amylose content varied between 7.50 and 28.58%. Optical and scanning electron microscopy (SEM) revealed the polyhedral shape of the native starch granules and deformation of the shape upon enzymatic hydrolysis. Second harmonic generation (SHG) microscopy and X-ray diffraction (XRD) analysis confirmed the presence of and variations in starch crystallinity. XRD revealed spectral peaks characteristic of A-type starch crystals in the native form. The elevated intensity of XRD peaks in hydrolyzed starch granules confirmed the occurrence of amylose hydrolysis rather than hydrolysis in amylopectin regions. Fourier transform infrared (FTIR) spectra revealed the common stretching and bending of bonds in all native starches;however, changes were observed in the fingerprint region (1080, 1000, 926 cm-1) of hydrolyzed starch granules, which indicates the amylolysis of the amylose region and disturbances in the ordered arrangement in the crystalline part. Differential scanning calorimeter (DSC) endotherms revealed the highest and lowest gelatinization peak temperatures in Harfoni (78 degrees C) and Tulosi Sali (41 degrees C) rice cultivars, respectively. The findings in this study can help to optimize the usage of rice starch in food and non-food industries. Furthermore, understanding the control points of starch digestion and genetically tailoring rice grains with different digestibility could be beneficial for nutraceutical applications.

关键词： digestion properties   high-speed shearing   particle size   rheological properties   starch nanoparticles  

摘要： This study is the first to investigate the relations between particle size and physicochemical properties of starch nanoparticles (SNPs) prepared by the combination of high-speed shearing and precipitation. Results show that this new approach allows to produce SNPs in nanoscale range of 157.8-859.4 nm by modifying the main operating parameters regarding the effect of starch variety, shearing speed, and shearing time. Interestingly, with decreasing the average particle size of potato starch nanoparticles (PtS-SNPs), the apparent amylose content, solubility, loss modulus, flow behavior index, rapidly digestible starch content, equilibrium hydrolysis percentage, and kinetic constant increased, whereas the swelling power, storage modulus, consistency coefficient, slowly digestible starch content, resistant starch content decreased. These findings suggest the significant impact of average particle size on the physicochemical properties of PtS-SNPs, which provides useful information for the utilization of these size controlled PtS-SNPs with desirable physicochemical properties in product development for different demands.

关键词： PLA   ZnO nanoparticles   Zataria multiflora   Mentha piperita   Nanocomposites  

摘要： The main shortcoming of polylactic acid (PLA) for packaging applications is its brittleness. Thus, there is a pronounced interest in the potential use of PLA/zinc oxide nanoparticle (ZnO NP) systems as active food packaging. In this study, ZnO NPs and two types of essential oils (EOs) including Zataria multiflora L. (ZEO) and Mentha piperita L. (MEO) at different concentrations (0.5%, 1%, 1.5% w/w) were used for the production of active PLA-based bionanocomposites for packaging applications. The presence of ZnO NPs and EOs led to increased film thickness and improved contact angle properties. ZnO NPs boosted the PLA-based films' WVP, whereas the EOs had the opposite effect. The increase in the ZEO and MEO content reduced the ultimate tensile strength and Young's modulus and increased the elongation at break. The X-ray diffraction and Fourier transform infrared spectroscopy results confirmed that the improvements are related to the ZnO NPs exfoliation and good interaction between PLA and ZnO NPs in the presence of EOs. Differential scanning calorimetry analysis showed that the incorporation of ZnO NPs increased the glass transition temperature (T-g), but did not change the melting temperature (T-m), though the addition of the EOs lowered the values of both parameters. Morphology analysis by scanning electron microscopy and atomic force microscopy showed that the presence of ZEO/MEO led to increased pinholes, pores, and roughness in the microstructure of the films. These results revealed that ZnO-PLA films containing EOs may be used as controlled release antimicrobial food active packaging.

关键词： Hippophae salicipholia seed oil   Ultrasound extraction   Carotenoid   Antioxidant activity   Oxidative stability  

摘要： Effects of ultrasound-assisted extraction (UAE) conditions viz., treatment time, temperature, solvent to sample ratio, and ultrasound power on antioxidant activity, stability, and extraction efficiency of oil from sea buckthorn (Hippophae salicipholia) seed were studied. The treatment time, temperature, and power showed a significant effect (p < 0.05) on the extraction yield and quality of sea buckthorn seed oil (SBSO). The UAE process could achieve a maximum oil recovery of 6.87 g. hg- 1and was significantly higher than that by the solvent extraction technique. The optimum values of UAE conditions attained were at 50 degrees C for 8.28 min at 552 W ultrasound power with a solvent to sample ratio 10:1 (mL: g). The SBSO samples revealed high carotenoid content (237.04 +/- 3.86 mg per 100 g beta-carotene equivalent), potent free radical scavenging ability (1.42 +/- 0.01 IC50 mu g per mL), and oxidative stability (totox value = 8.04 +/- 0.02) upon the UAE treatment. GC-MS profiling of the oil sample extracted at optimum UAE conditions exhibited better retention of fatty acids.

关键词： functional properties   isoelectric precipitation   Lens culinaris   Lentil protein  

摘要： Background and objectives Providing information on protein structure and functionality is essential for evaluating the potential of specific agricultural commodities to be utilized as plant-based protein sources. Amino acid composition, secondary structure, surface charge, thermal, and functional properties of proteins isolated from five local lentil landraces were investigated. Secondary objective of the study was to investigate if a relationship exists between the amino acid composition and the physicochemical or functional properties of the isolates. Findings Aspartic acid and glutamic acid were found to be the dominant amino acids in the isolates while they were poor in methionine. Denaturation temperatures of isolates ranged between 96-108 degrees C and their secondary structure mainly consisted of beta-sheet. Emulsion capacity, emulsifying activity (EAI), and emulsion stability indices (ESI) of isolates were found to be between 403.8-468.2 g oil/g protein, 18.8-24.2 m(2)/g, and 43.4-125.5 min, respectively. Foaming capacity of the isolates changed between 71% and 91% whereas their least gelation concentration varied between 110 and 150 g/L. Conclusions Yusufhan isolate which had relatively higher acidic amino acid content showed the highest net charge and solubility at acidic pH. Tigris isolate which had higher hydrophobic amino acid content compared to the other isolates showed relatively high thermal stability, EAI and ESI. Significance and novelty Findings of the study make a contribution toward the potential use of local lentil landraces as sources for extracting protein-based ingredients.

关键词： Bacteria  

摘要： Different aquaculture modes have been developed in the past decade. This study evaluated the impact of different fish aquaculture modes on the physiochemical changes and microbiota composition of grass carp fillets during 4 degrees C storage. The total viable counts of container-cultured grass carp were 1 day later than that of pond-cultured group to exceed 7 log CFU/g. Its sensory scores were higher than that of pond-cultured group after day 9. The total volatile basic nitrogen and hypoxanthine in container-cultured group were 26.00% and 47.78% lower than that in pond-cultured group on day 11, respectively. However, the concentration of trichloroacetic acid -soluble peptides and putrescine in container-cultured group were higher than the pond-cultured group on day 11. The initial microbiota of grass carp fillets in both groups was Acinetobacter. However, the dominant spoilage bacteria in pond-cultured and container-cultured grass carp on day 11 were Shewanella and Pseudomonas, respectively. Novelty impact statement On the one hand, our study firstly reported the dominant spoilage bacteria in pond-cultured and container-cultured grass carp were different, which may cause the different quality of grass carp under the two different aquaculture modes. On the other hand, our results showed that the shelf life of container-cultured grass carp was at least 14.29% longer than the pond-cultured group. In conclusion, our results can provide information for researchers and industries to compare the advantages and disadvantages of different aquaculture modes and develop the quality control technology of fish cultured in different modes in the future.

关键词： annealing   cross-linking   digestibility   dual modification   pasting properties  

摘要： Native maize starch (NS) is modified by annealing (ANN) and cross-linking (CL) processes, and also by using two different combinations of the ANN and CL processes (ANN-CL and CL-ANN). The effects of modifications on physicochemical properties and in vitro digestibility of starch are studied. The results show that CL-ANN significantly (p < 0.05) improves swelling power and decreases solubility. The reduction in breakdown and setback indicate that ANN-CL and CL-ANN improve shear resistance and anti-retrogradation effect of starch. All the modified starches exhibit native A-type crystals but show higher crystallinity than native starch. The decreased enthalpy of the CL-ANN starch is due to starch granule rupture during the treatment process. Scanning electron microscopy shows that ANN results in the formation of starch clusters, which are also present in CL-ANN and ANN-CL starches. The surface of CL starch is rough and partially cracked. CL-ANN significantly (p < 0.05) increases the content of resistant starch to 10.74%. Physicochemical properties and digestibility of CL and ANN dual-modified starches are related to the different combinations of the modification processes. Thus, dual modification using cross-linking and annealing is an effective method to improve the properties of starch, thus broadening its application in the food industry.