Impact of apple procyanidins on sensory perception in model cider (part 2): Degree of polymerization and interactions with the matrix components

The impact of the degree of polymerization (DP) of procyanidins and its interactions with fructose, acidity and alcohol in a model solution of cider was investigated. Four sensory characteristics (bitterness, astringency, sweetness and sourness) were studied. At 750 mg/L of procyanidins, the DP impacted astringency and bitterness but not sweetness or sourness. The medium DP (tetramer) of apple procyanidins was the most bitter and astringency increased with the DP. The impact of ethanol, fructose and acidity on the four sensory attributes was also examined. These results provide insights into how the components interact to produce the taste of cider.     

Chemical and sensory evaluation of Bordeaux wines (Cabernet-Sauvignon and Merlot) and correlation with wine age

Wine quality study was carried out with 24 vintages of Cabernet-Sauvignon (CS) and 7 vintages of Merlot (M) produced by two different Bordeaux wine-growing areas. Proanthocyanidin monomers and oligomers were identified and quantified by HPLC-UV-Fluo. Percentage of galloylation (%G), of prodelphinidins (%P) as well as mean degree of polymerisation (mDP) were also determined. Total phenolic compounds, total anthocyanins, total tannins, hue, CI (colour intensity), titratable acidity, ethanol level and pH were evaluated. Sensory analysis concerning astringency and bitterness intensity was also performed. Total phenolic compounds, total anthocyanins, total tannins, tannin monomers, hue, CI, % G, % P, mDP and astringency intensity differentiate both wines (M and CS) according to vintage. Correlations between wine age and: mDP, hue, astringency and tannin monomers (C + EC) are obtained. Qualitative tannin characterisation is established by correlation between astringency and mDP (R² = 0.509, p = 0.051, CS; R² = 0.780, p = 0.000 M). In addition, mDP decreases significantly during ageing (R² = 0.796, p = 0.000; CS and R² = 0.946, p = 0.000; M). Scale patterns between wine mDP and tannin perception (astringency) are proposed.     

Impact of appearance on degree of liking and eating quality expectations of selected apple cultivars

This study investigated the effect of taste expectations based on cultivar recognition on the preference for apple‐eating quality. Consumer preference for eating quality was assessed using three levels of product information, viz. (i) no visual information, (ii) a photograph depicting the typical appearance of the specific cultivar and (iii) an incorrect photograph, misleadingly depicting a different cultivar. Consumers scored the eating quality of ‘Pink Lady^?’ served with the correct photograph significantly higher compared with presentation without pictorial information, suggesting a positive image for this trademark cultivar. Conversely, consumers had lower eating quality expectations for ‘Starking’ and ‘Golden Delicious’ indicated by lower scores when supplied with matching photos. Cultivar developers and researchers should be mindful of the confounding effect of fruit appearance on the hedonic assessment of eating quality. The order of presentation (matching or wrong photograph first) affected the preference scores and should be considered in future studies.     

The effects of green tea drinking on salivary polyphenol concentration and perception of acid astringency

Samples of dilute HCl intended to result in mixtures with saliva with pH levels below, near and above the level of maximum protein-polyphenol interaction were presented to panelists. Significant differences in astringency were seen, but no evidence of a decline in astringency with stronger acid.Panelists abstained from tea drinking for some time, then drank two or more cups of green tea per day for some days, and finally omitted tea drinking for a period. Salivary polyphenol levels were determined throughout the experiment. Drinking green tea resulted in a highly significant (p < 0.01) increase in salivary polyphenol levels that persisted for some days. Very dilute HCl solutions (0, 0.005, 0.006 and 0.007 N) were presented to panelists before, during and after the period of tea drinking and rated for astringency and sourness. Astringency and sourness intensity ratings increased significantly (p < 0.01) during the period of tea drinking. It appears that there is a metabolic pool of polyphenol that is influenced by dietary habits. It appears likely that the salivary polyphenol level influences perception of astringency caused by acids.     

Brewing of glucuronic acid-enriched apple cider with enhanced antioxidant activities through the co-fermentation of yeast (Saccharomyces cerevisiae and Pichia kudriavzevii) and bacteria (Lactobacillus plantarum)

Co-fermentation using yeast (Saccharomyces cerevisiae and Pichia kudriavzevii) and the bacteria (Lactobacillus plantarum) as starters isolated from spontaneous sourdough was conducted for the brewing of glucuronic acid (GlcA)-enriched apple cider. The concentration of GlcA in the apple cider co-fermented for 14 d with commercial S. cerevisiae and L. plantarum was 37.7 ± 1.7 mg/mL while a concentration of 62.8 ± 3.1 mg/mL was recorded for fermentation with P. kudriavzevii and L. plantarum, which was higher than the corresponding single yeast fermentation. The co-fermented apple cider revealed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 171.67 ± 0.79 µg trolox equivalents (TE)/mL using P. kudriavzevii and L. plantarum, compared to the control (143.89 ± 7.07 µg TE/mL) just using S. cerevisiae. Thus, the co-fermentation of S. cerevisiae and L. plantarum and P. kudriavzevii and L. plantarum provided a new strategy for the development of GlcA-enriched apple cider with enhanced antioxidant capacity.     

Relating the effect of saliva-induced emulsion flocculation on rheological properties and retention on the tongue surface with sensory perception

Perception of food emulsions can often not be directly related to the structure of the products before consumption. Taking into account the changing product structure upon oral processing might increase understanding of the relation between perception and product properties.     

Modeling the diffusion-adsorption kinetics of 1-methylcyclopropene (1-MCP) in apple fruit and non-target materials in storage rooms

The purpose of this research was to model the kinetics of adsorption of 1-methylcyclopropene (1-MCP) in apple fruit and non-target solid materials found in apple storage rooms. The process was described by Fick’s second law of diffusion of the gas through the pores of the material coupled with adsorption kinetics of the gas on the material’s binding sites. A finite element formulation of the model, describing the diffusion and adsorption mechanisms separately, was first developed. The values of the relevant parameters were estimated based on headspace measurements of the decrease of 1-MCP in jars containing the different materials. The headspace concentration of 1-MCP was measured using gas chromatography. Apple fruit (Golden Delicious and Jonagold) and the following bin construction materials were investigated: high density polyethylene (HDPE), oak, poplar wood and card lining. The range in the magnitude of the diffusion coefficient, adsorption coefficient, and concentration of active sites in the various solids was 10,000-, 8-, and 30-fold, respectively.     

高粱原花青素对生长育肥猪抗氧化、免疫以及养分消化率的影响

研究高粱原花青素(sorghum procyanidins,SPC)对生长育肥猪生长性能、养分消化率、消化酶活性、免疫力和抗氧化能力的影响。160头70日龄、平均体重为(31. 28±1. 12) kg的杜×长×大三元杂交猪,按照单因素完全随机设计分为4个组,分别饲喂玉米-豆粕基础日粮,以及基础日粮中添加100、150、200 mg/kg SPC。实验期为14周,生长期和育肥期各7周。在每个实验阶段开始和结束时称重,每天记录采食量,计算各阶段平均日增重(ADG)、平均日采食量(ADFI)和料重比(F/G)。在每个实验阶段的最后3 d,收集粪样测养分消化率。在每个实验阶段结束时,采血测血清抗氧化指数和免疫参数,同时,每个重复随机屠宰2头猪,取胰腺组织,测消化酶活性。结果表明,日粮添加SPC对生长育肥猪的生长性能没有显著的促进作用(P 0. 05)。在生长猪阶段,日粮添加150 mg/kg和200 mg/kg SPC显著降低了消化酶的活性,对养分消化率有降低的趋势。在育肥猪阶段,日粮添加150 mg/kg显著提高了粗蛋白的表观消化率(P 0. 05),200 mg/kg SPC显著地抑制了消化酶的活性(P 0. 05)。与对照组相比,不论是在生长期还是育肥期,添加150 mg/kg或200 mg/kg的SPC均显著地增强了猪血清谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD)的活性以及血清总抗氧化能力(T-AOC)(P 0. 05),降低了血清丙二醛(MDA)浓度(P 0. 05),提高了猪血清IgG、IgM和白细胞介素2(IL-2)的浓度(P 0. 05)。总之,SPC有利于提高生长育肥猪抗氧化能力,增强免疫力,但是对于生长育肥猪的生长性能及养分消化率没有显著的促进作用,相反,高浓度的SPC甚至抑制了消化酶的活性,从而影响养分的消化利用。     

Adapting tribology for use in sensory studies on hard food: The case of texture perception in apples

Application of tribology in food systems has primarily focused on liquids and semi-solids. The present study examined texture perception in a solid food, using apples as the proof-of-concept. The study aimed to assess a) the ability of tribological measurements to predict a multicomponent sensory property (mealiness) in hard food, and b) the impact of two common motion patterns (rotational and linear reciprocating) on tribological measurements and mathematical correlations with sensory texture of a hard food. The textures of ten apple varieties were evaluated by a trained sensory panel while friction and wear behavior were measured instrumentally. Spearman correlations indicated that texture attributes (crisp, juicy, mealy, and rate of melt) significantly correlated with total penetration depth (p < 0.05) and with friction coefficients during the transient (non-equilibrium) phase (p < 0.05), but not with friction coefficients from the steady-state phase in both rotational and linear tribology (p > 0.05). This was an important finding as the steady-state phase is predominantly used in food tribology research, yet our findings showed poor correlations with steady-state data, while showing strong correlations with sensory perception in the transient phase. The strong mathematical correlations found in the transient phase suggest that test conditions that provoke a dynamic friction response from the sample may more closely resemble the conditions under which humans perceive friction during oral processing.     

Analysis of key aroma components in cider from Shaanxi (China) Fuji apple

Aroma components play an important role in the quality of cider. To understand the contribution of every component to cider aroma quality, major aroma components present in ten ciders processed with different technological methods with different yeasts and apple orchards were determined by Headspace-solid phase microextraction–gas chromatography–mass spectrometry and internal standard method. Experimental results by principal component analysis indicated that ethyl acetate, acetic acid isobutylester, isopentylacohol acetate, ethyl caprylate, ethyl 4-hydroxybutanoate, isopentylalcohol, 3,4,5-trimethyl-4-heptanol, nonyl alcohol, 3-methylthio-1-propanol serve as the key aroma components in cider from Shaanxi (China) fuji apple. A model was established and verified for evaluating aroma quality based on factor analysis by comparing with the sensory evaluation method.     

海南蒲桃原花青素DPPH自由基清除活性及稳定性的初步研究

从海南蒲桃果实提取原花青素,研究了原花青素清除DPPH自由基的活性及温度、光照及pH对海南蒲桃原花青素清除DPPH自由基活性的影响。结果:海南蒲桃原花青素对DPPH自由基的半抑制剂量IC50为5.9077μg/mL。20～80℃处理8h原花青素DPPH自由的清除率与初始值差异不显著,90℃处理3h和100℃处理2hDPPH自由的清除率与1h间差异显著。120℃及130℃处理30min分别较初始的DPPH自由基清除率低5.68%和20.46%;pH1～9处理8d对原花青素自由基清除活性无显著降低,pH10处理2d及pH11～12处理1d原花青素DPPH自由基清除活性较初始值显著下降。光照度3418lx以下照射8d自由基清除率较初始值无显著差异,45～70klx太阳光处理8h自由基的清除率降低14.80%。     

不同杂交后代苹果与富士苹果的多酚氧化酶特性比较

不同杂交后代苹果54号、45号及富士苹果多酚氧化酶特性比较结果表明：不同苹果的最适pH值不同，45号和富士为5．5，54号为6．0；45号、54号和富士最适温度分别为30，35，40℃；富士热稳定性最强，其次是45号，最次为54号；不同苹果PPO的最适底物依次为绿原酸、咖啡酸、儿茶酚；Na2S203对PPO活性抑制效果最佳，L-半胱氨酸与抗坏血酸的抑制效果较好，EDTA-2Na的抑制效果较差；不同苹果PPO同工酶酶带不同，染色深浅不同。富士有四条酶带，45号和54号只有一条共有酶带，富士酶带数最多，染色最深。     

Evaluation of drying models of apple (var. McIntosh) dried in a convective dryer

Drying behaviour of apple particles was investigated in a laboratory type dryer. The effect of drying air temperature, airflow velocity, initial height of layer, particles shape and size on the dehydration characteristics of apples was investigated. Increase in drying air temperature and increase in the airflow velocity caused a decrease in the drying time and an increase in drying rate. Increase in initial height of layer and increase in the sample thickness caused an increase in the drying time and decrease in drying rate. Drying time of the cubes was shorter and their drying rate was higher than for slices. The experimental dehydration data of apple particles obtained were fitted to the semi‐theoretical, empirical and theoretical models. The accuracies of the models were measured using the correlation coefficient (R), mean bias error (MBE), root mean square error (RMSE), reduced chi‐square (χ²), and t‐statistic method. All models described the drying characteristics of apple particles satisfactorily (R > 0.9792). The Logarythmic model can be considered as the most appropriate (R > 0.9976, MBE = ?10^?11?4.5 × 10^?6, RMSE = 0.00287–0.01746, χ² = 8.5 × 10^?6?3.1 × 10^?4, t‐stat = 7.3 × 10^?9?1.2 × 10^?3). The effect of drying air temperature, airflow velocity, characteristic dimension of the particle and initial height of layer on the drying models parameters were also determined.     

Primary metabolites and organic acid metabolism in apple (Malus sylvestris) fruit callus culture

In-vitro culture cells were obtained from seven different varieties of Indian apples (Malus sylvestris L). The cultivar Golden Delicious showed the highest yield of callus tissue followed by Maharaji and American Epirouge. Cultured apple cells exhibited some deviation from the apple fruit in primary metabolism as well as primary metabolite profiles. In callus cultures, the pool size of free amino acids and organic acids increased considerably while the free sugar pool decreased drastically compared with apple fiuit. There was higher incorporation of ¹⁴C acetate, ¹⁴C citrate, ¹⁴C malate and ¹⁴C succinate into the CO₂, lipid, protein, carbohydrate and amino acid fractions and lower incorporation into the free sugar fraction in cultured cells compared with the explant. The incorporation of ¹⁴CO₂ showed a similar trend. Qualitatively, there was some similarity between the callus and explant in free amino acid and sugar profiles and dissimilarity in organic acids. Compounds such as citrate, succinate and fumarate and also some amino acids (methionine, arginine, leucine and proline) were present at higher concentration in callus cultures whereas they were almost absent in the original tissue. There were also differences in the carbohydrate and protein profiles of explant ana callus as judged by their sugar and amino acid make-up respectively.     

Radiofrequency inactivation of oxidative food enzymes in model systems and apple derivatives

The effect of increasing radiofrequency (RF) electric fields on the activity of oxidative enzymes was studied in model systems and food. In particular, the mechanisms of enzyme inactivation by RF treatments were studied on polyphenoloxidase (PPO) and lipoxygenase (LOX) model systems. RF treatments efficiently inactivated both enzymes, although PPO was more sensitive to an increase in the RF electric field. RF efficacy was attributed to the generated thermal effect, while the contribution of the electromagnetic field resulted negligible.Following, the efficacy of RF in blanching vegetables to obtain color stable derivatives was evaluated. To this aim, RF and conventionally water blanched apples were processed to get purees which were analyzed for color, sensory attributes and consumer preference. RF allowed apples to be adequately blanched. In particular, the puree obtained from the RF blanched apples was judged comparable to the conventionally water blanched one for color and sensory attributes. However, a slightly higher perceivable sweetness of the RF blanched sample was found, probably due to the fact that the RF treatment allowed any contact with water to be avoided.     

陕北小粒黑豆皮原花青素提取工艺及抗氧化性研究

提取陕北小粒黑豆皮中原花青素,考察乙醇浓度、提取时间、提取温度和液料比对其提取得率的影响,利用Box-Behnken设计试验,建立提取过程的数学模型及二次多项式回归方程,预测出最优提取条件,并对提取的原花青素进行抗氧化性研究。结果表明,陕北小粒黑豆皮提取原花青素的优化工艺条件为提取时间4.2h、提取温度53℃、液料比22:1(mL/g)、乙醇浓度60%,在该条件下提取得率为5.380%;原花青素对DPPH自由基、羟基自由基和超氧阴离子均具有一定的清除效果,其IC_(50)值分别为0.075,0.590,0.220mg/mL。     

Nonthermal inactivation and sublethal injury of Lactobacillus plantarum in apple cider by a pilot plant scale continuous supercritical carbon dioxide system

The objective of this study was to evaluate the efficacy of supercritical carbon dioxide (SCCO₂) for inactivating Lactobacillus plantarum in apple cider using a continuous system with a gas-liquid metal contactor. Pasteurized apple cider without preservatives was inoculated with L. plantarum and processed using a SCCO₂ system at a CO₂ concentration range of 0-12% (g CO₂/100 g product), outlet temperatures of 34, 38, and 42 °C, a system pressure of 7.6 MPa, and a flow rate of 1 L/min. Processing with SCCO₂ significantly (P < 0.05) enhanced inactivation of L. plantarum in apple cider, resulting in a 5 log reduction with 8% CO₂ at 42 °C. The response surface model indicated that both CO₂ concentration and temperature contributed to the microbial inactivation. The extent of sublethal injury in surviving cells in processed apple cider increased as CO₂ concentration and processing temperature increased, however the percent injury dramatically decreased during SCCO₂ processing at 42 °C. Structural damage in cell membranes after SCCO₂ processing was observed by SEM. Refrigeration (4 °C) after SCCO₂ processing effectively inhibited the re-growth of surviving L. plantarum during storage for 28 days. Thus this study suggests that SCCO₂ processing is effective in eliminating L. plantarum and could be applicable for nonthermal pasteurization of apple cider.     

Preparation and radical scavenging activities of polymeric procyanidins nanoparticles by a supercritical antisolvent (SAS) process

The aim of this study was to prepare nanoscale polymeric procyanidins (PPC) by the supercritical antisolvent precipitation process (SAS), to improve the radical scavenging activities of PPC. Nanoscale PPC was successfully achieved by SAS. The effects of process parameters like temperature, pressure, solution flow rate and solution concentration have been investigated to reveal their impact on the mean particle size of the final product. We obtained microspheres with mean diameters ranging from 100 to 200 nm. The processed and unprocessed PPC was characterised by scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, differential scanning calorimeters, fourier-transform infrared spectroscopy and specific surface area analysis. The solubility of PPC precipitated using SAS process was significantly increased in comparison with unprocessed PPC. Moreover, the nanoscale PPC demonstrated higher antioxidant activities than unprocessed PPC. These results indicate that nanoscale PPC might be of interest to be used as a natural antioxidant.