Assessment of apple (Malus × domestica Borkh.) fruit texture by a combined acoustic-mechanical profiling strategy

Texture of apple fruit originates from anatomic traits related to cell wall architecture and is one of its most important quality characteristics, thus there is the desire to better understand the different factors which contribute to apple texture. Here we present a novel approach based on the simultaneous profiling of the mechanical and acoustic response of the flesh tissue to compression, using a texture analyzer coupled with an acoustic device. The methodology was applied to a 86 different apple cultivars, measured after two months postharvest cold storage and characterised by 16 acoustic and mechanical parameters. Statistical treatment of the data with principal component analysis (PCA) allowed for the identification of three groups of variables, the mechanical ones being clearly distinguished from the acoustic ones. Moreover, the distribution of the apple cultivars in the multivariate PCA plot allowed characterisation of the cultivars according to their textural performance. Each cultivar was analyzed also with non-destructive vis/NIR spectroscopy in order to determine impartially the ripening stage. Sensory evaluation by panellists was performed on a selected group of cultivars and sensory data correlated with the acoustic-mechanical data. The results demonstrate the good performance of our combined acoustic-mechanical strategy in measuring apple crispness as it is perceived by human senses.     

Anatomical and biochemical trait network underlying genetic variations in tomato fruit texture

Firmness is an indicator of fruit freshness and a main component of tomato (Solanum lycopersicum) fruit texture. In this work, the genetic variability in fruit firmness and stiffness was analyzed in pre- and postharvest periods and underlying anatomical and biochemical traits were identified. Three tomato contrasted parental lines and six derived quantitative trait loci (QTL)-NILs harboring texture QTL on chromosome 4 (QTL4) and 9 (QTL9) were analyzed; the seasonal variability was assessed on two distant trusses. Firmness and stiffness were measured by compression and puncture tests at harvest and after 7-day storage at 20 °C. QTL4 poorly influenced the textural variables, on the contrary to QTL9 which increased firmness measured by puncture test and had similar effects in the two genetic backgrounds. According to this test, firmness increased along the season, but ranks among genotypes and QTL effects were hardly affected. Only some of the QTL effects were still significant after storage and firmness losses were not predicted by firmness at harvest. Fruit firmness and stiffness measured by puncture tests correlated with both morphological (locular number, R = −0.89), histological (cell size, R < −0.80) and biochemical (dry matter (R > 0.82) and soluble sugar content (R < −0.74)) fruit traits. In contrast, compression test values hardly correlated with any of the measured traits. This work provided an original comprehensive approach to analyse fleshy fruit firmness and paves the way for a future predictive model.     

Apple firmness: Creating a tool for product evaluation based on a sensory–instrumental relationship

In studies with trained and untrained participants, we have demonstrated that people can discriminate differences in texture between apples that differ by more than ∼5 N in instrumental puncture tests [Harker, F.R., Gunson, F.A., Brookfield, P.L., White, A., 2002a. An apple a day: the influence of memory of consumer judgement of quality. Food Qual. Prefer. 13, 173–179; Harker, F.R., Maindonald, J., Murray, S.H., Gunson, F.A., Hallett, I.C., Walker, S.B., 2002b. Sensory interpretation of instrumental measurements 1: texture of apple fruit. Postharvest Biol. Technol. 24, 225–239]. Using this information, it is possible to estimate the probability that a consumer will perceive a difference between apples selected at random from two lines of fruit (e.g. apples harvested from different orchards) based on knowledge of the distribution of instrumental values in each product line. The data we present demonstrates the overwhelming impact of biological variability on attempts to use instrumental–sensory relationships to predict product quality in apples. Calculations predicted that two lines of fruit needed to differ by about 12 N (mean puncture force) in order for consumers to perceive a difference in sensory texture (p = 0.95). At a practical level, curves are provided to enable researchers to infer the probability with which consumers may perceive differences between apples from treatments that differ in mean puncture force.     

Relationships between the instrumental and sensory characteristics of four peach and nectarine cultivars stored under air and CA atmospheres

‘Big Top’ and ‘Venus’ nectarines and ‘Early Rich’ and ‘Sweet Dream’ peaches were picked at commercial maturity and stored for 20 and 40 d at −0.5 °C and 92% RH under either air or one of the three different controlled atmosphere regimes (2 kPa O₂/5 kPa CO₂, 3 kPa O₂/10 kPa CO₂ and 6 kPa O₂/17 kPa CO₂). Physicochemical parameters and volatile compounds emission were instrumentally measured after cold storage plus 0 or 3 d at 20 °C. Eight sensory attributes were assessed after cold storage plus 3 d at 20 °C by a panel of 9 trained judges, in order to determine the relationship between sensory and instrumental parameters and the influence of storage period and cold storage atmosphere composition on this relationship.A principal component analysis (PCA) was undertaken to characterize the samples according to their sensory attributes. PCA results reflected the main characteristics of the cultivars: ‘Big Top’ was the nectarine cultivar with the highest values for sweetness, juiciness and flavor; ‘Sweet Dream’ was the sweetest peach and was characterized by high values for crispness and firmness, while ‘Venus’ and ‘Early Rich’ were characterized by their sourness. To assess the influence of storage period and CA composition on sensory properties, a PLS model of the flavor of the different samples was constructed using standard quality attributes and volatile concentrations as the X-variables. The model with 2 factors accounted for more than 80% of flavor variance. PLS results indicated that the main influence on flavor perception was storage period. Atmosphere composition also had an influence on flavor perception: flavor perception decreased from samples stored in a 2/5 O₂/CO₂ atmosphere composition to those of 3/10 and 6/17. These results can be qualitatively extended to juiciness and sweetness since all these sensory properties were strongly correlated.     

Predicting sensory attributes of different chicory hybrids using physico-chemical measurements and visible/near infrared spectroscopy

Chicory (witloof) is a typically Belgian vegetable appreciated for its slightly bitter taste. Up until now no measurements exist to objectively quantify the sensory characteristics of chicory. Taste and texture of nine different chicory hybrids were analyzed by sensory and instrumental analysis (three-point bending test, high performance anion exchange with pulsed amperometric detection, high performance liquid chromatography and visible/near infrared spectroscopy). The main objective of the study was to correlate and predict the sensory attributes and consumer acceptance of chicory with destructive physico-chemical measurements and non-destructive Vis/NIR data, to avoid time- and money-consuming sensory profiling in the future. A univariate analysis showed that glucose and sucrose concentrations in chicory leaves were highly correlated with the attributes crunchiness and bitterness. The fructose concentrations however were correlated with the sweetness score of the panel. When performing partial least squares on all destructive instrumental parameters and Vis/NIR data for the major sensory attributes of chicory, satisfactory prediction models (ratio of standard deviation to root mean square error of cross-validation (RPD) > 2) could be established for all attributes but sweetness using all physico-chemical parameters. Using Vis/NIR data improved the prediction capacity of the sweetness model, and this technique proved to be useful in predicting the sensory quality of chicory.     

Aloe vera based edible coatings improve the quality of minimally processed ‘Hayward’ kiwifruit

This article studies the efficacy of an edible coating based on Aloe vera gel at four different concentrations (0, 1, 5, 15% (v/v)) in maintaining the quality of fresh-cut kiwifruit. The kiwifruit slices were packaged under passive atmosphere and stored at 4 ± 1 °C. Quality attributes such as colour and texture (firmness and texture profile analysis), titratable acidity, total soluble solids, pectin content, microbial load and sensory parameters were evaluated during storage. In general, Aloe vera coating reduced respiration rates and microbial spoilage in sliced kiwifruit. After seven days of storage, the mesophilic load dropped by approximately one logarithmic unit for slices coated with 15% and 5% Aloe vera. Total pectin depolymerization was also lower in the treated samples and the texture of the uncoated samples deteriorated more rapidly than the treated slices during storage. Furthermore, due to the atmospheric composition and the microbial load, the quality of the control samples declined after six days of storage. Our results show that an Aloe vera coating improved the quality of stored kiwifruit slices. The best results obtained in the instrumental texture profile and in the preference panel test were with the 5% coating, indicating that this may be a healthy alternative coating for fresh-cut kiwifruit.     

QTL mapping of volatile compounds in ripe apples detected by proton transfer reaction-mass spectrometry

The availability of genetic linkage maps enables the detection and analysis of QTLs contributing to quality traits of the genotype. Proton Transfer Reaction Mass Spectrometry (PTR-MS), a relatively novel spectrometric technique, has been applied to measure the headspace composition of the Volatile Organic Compounds (VOCs) emitted by apple fruit genotypes of the progeny ‘Fiesta’ × ‘Discovery’. Fruit samples were characterised by their PTR-MS spectra normalised to total area. QTL analysis for all PTR-MS peaks was carried out and 10 genomic regions associated with the peaks at m/z = 28, 43, 57, 61, 103, 115 and 145 were identified (LOD > 2.5). We show that it is possible to find quantitative trait loci (QTLs) related to PTR-MS characterisation of the headspace composition of single whole apple fruits indicating the presence of a link between molecular characterisation and PTR-MS data. We provide tentative information on the metabolites related to the detected QTLs based on available chemical information. A relation between apple skin colour and peaks related to carbonyl compounds was established. The two authors contributed equally to this work.     

Effect of storage conditions on chemical and physical characteristics of hazelnut (Corylus avellana L.)

This study evaluated the effect of different storage conditions currently used by the industry, on the chemical, physical and sensory characteristics of ‘Tonda Gentile delle Langhe’ hazelnuts, during one year of storage. The traditional method of in-shell preservation in a storage room at ambient temperature was compared with refrigerated storage of shelled nuts at 4 °C and 55% relative humidity, with or without modified atmosphere (1% oxygen, 99% nitrogen). The following parameters were measured: moisture content, lipid content, total phenolic content, and antioxidant capacity of the kernel; acidity and peroxide value of the oil. The kernel resistance to breakage was evaluated by texture analysis using a compression test. The hazelnuts were also evaluated by sensory analysis. The results showed that the acidity and the peroxide value were the most discriminating parameters. After one year of storage, the acidity of hazelnuts stored at ambient temperature (0.47% oleic acid) was higher than the value considered the acceptable limit after storage (0.40% oleic acid), while refrigerated storage maintained a low level of acidity and lipid oxidation, with the best performance in modified atmosphere (0.13% oleic acid; 0.057 O₂ mmol kg⁻¹). Sensory analysis after 12 months also showed differences among the three storage treatments. In-shell storage of hazelnuts at ambient temperature was able to preserve the kernels below threshold limits of acidity and oxidative degradation for up to 8 months, but refrigeration was necessary to maintain high quality for up to one year. The use of modified atmosphere is recommended for long periods of storage.     

Effect of prolonged cold storage on the sensory quality of peach and nectarine

To maintain peach and nectarine quality after harvest, low temperature storage is used. Low temperatures induce physiological disorders in peach, but the effect of cold storage on the sensory quality of the fruit before it is damaged by chilling injury syndrome remains unclear. To evaluate the cold storage effect on the sensory quality two peach cultivars (’Royal Glory’ and ‘Elegant Lady’) and two nectarines (’Ruby Diamond’ and ‘Venus’) were harvested at a standardized firmness level and subjected to quality evaluations and sensory analysis at harvest and after storage at 0 °C for 35 d. For both time points, a supplementary ripening followed such that homogeneous flesh firmness and suitability for consumption was achieved.The fruit segregation through the Durofel firmness (DF), evaluated using a non-destructively method (Durofel device), allowed the formation of a uniform group of fruit in terms of flesh firmness (FF), showing scores between 45.1 and 55.9 N. The average FF in fruit ripened immediately after harvest was 22.9 N and 25.6 N in fruit ripened after cold storage for 35 d.The “acceptability” of fruit is highly correlated with “aroma”, “sweetness”, “juiciness”, “texture” and “flavor”. Only the “acid taste” parameter had no significant correlation with “acceptability” or with the other parameters evaluated.It is possible to conclude that the sensory quality and acceptability of peach and nectarine are characteristic of each cultivar and change, depending on the time elapsed after harvest. In general, it was confirmed that nectarine cultivars have a more consistent quality than peach cultivars.     

Surface decontamination of fresh-cut apple by pulsed light: Effects on structure,colour and sensory properties

The effect of pulsed light at increasing fluence (17.5, 52.5, 105.0 and 157.5 kJ/m²) was studied with reference to germicidal efficiency and changes in fresh-like appearance of sliced apple. Independent of fluence, viable counts and inoculated bacteria were reduced by 1 and 3 logs respectively. Fluence significantly affected weight loss, colour and sensory attributes of apple slices during storage at 6 °C. Pulsed light at 17.5 kJ/m² resulted in apple slices comparable to the untreated samples, with limited quality changes. By contrast, at higher fluence, apple slices underwent dehydration and browning due to loss of cell integrity. Exposure to high fluence treatments was also associated with negative changes in the flavour profile of sliced apple during storage.     

Effect of harvest maturity on quality of fresh-cut pear salad

Texture of an unripe pear is firm and crisp, similar to an apple. However, at the crisp stage, the flavor of pears is flat. This study evaluated the effect of harvest maturity on the quality of fresh-cut pear salad. Fruit were harvested at commercial maturity and 1-month delayed. After 2 and 5 months (1 and 4 months for delayed-harvest fruit) storage at ?1 °C, fruit were sliced into 8–12 wedges per fruit, dipped in an antibrowning solution, packaged in Ziploc bags and stored at 1 °C for up to 21 d. Delayed-harvest fruit were larger in size (≈20% increase in weight), had lower flesh firmness (≈17% decrease), lower titratable acidity content (≈20% decrease), and lower phenolic content (≈45% and 13% decreases in pulp and peel, respectively). There was no significant difference in soluble solids content. After 2 months storage, ethylene production and respiration rate were initially lower in the slices from delayed-harvest fruit, but tended to become similar after 7 d in storage at 1 °C. Delayed-harvest fruit had lower hydroxycinnamic acids and flavanols, and higher ester, alcohol, and aldehyde volatile compounds after 2–5 months storage. The results indicated that fruit salad produced with delayed-harvest pears had less browning potential and better flavor. Sensory evaluation results showed that about 80% of the panel liked slices from delayed-harvest fruit over commercial harvested, especially in terms of visual quality (65–85%), sweetness (75–95%), taste (70–80%), and overall quality (75–80%) during 21 d storage at 1 °C. The cut surface of slices appeared dry in delayed-harvest fruit when processed after 5 months in storage. However, sensory evaluation showed that panels still preferred the delayed-harvest fruit.     

冰温气调对红富士苹果贮藏效果的影响

研究了冰温条件下不同气体成分对红富士苹果果实生理及贮藏品质的影响。结果表明,八成熟红富士苹果的冰点为-1．5℃,其冰点温度与果实的成熟度呈负相关;适宜的冰温气调贮藏条件可明显地抑制红富士苹果呼吸及乙烯释放速率．减缓果实组织相对电导率的上升和杲肉硬度及可溶性固形物（TSS）的下降速率,贮藏8个月仍能保持良好的品质;红富士苹果较长期冰温贮藏的适宜气体指标为：O2 1％～3％,CO2〈2％。     

Estimation of genetic parameters in a recurrent selection program in Apple

Combining ability was estimated for 8 tree and 11 agronomic traits in a multi-location apple genetics population to select individuals for the next cycle of selections. Families more than three standard errors away from the general mean were identified for each trait and extreme individuals (with regard to that trait) from those families were selected. On the whole, 148 individuals were chosen based upon individual traits and, in a few cases a combination of traits, in a way that maintains the original diversity within the population. Narrow-sense heritability estimated separately for each site for fruit ribbing, fruit russet, fruit overcolour amount and fruit weight ranged from 0.0–0.13, 0.05–0.58, 0.34–0.40 and 0.27–0.90 respectively. Phenotypic correlation and additive genetic correlation were small and from small to moderately high respectively, between pairs of traits. The implication of these genetic parameter estimates in apple breeding is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Volatile compounds,quality parameters and consumer acceptance of ‘Pink Lady®’ apples stored in different conditions

Standard quality parameters, consumer acceptance, and volatile compound emission of ‘Pink Lady^®’ apples (Malus × domestica Borkh.) were measured at harvest and after 14 and 25 weeks of cold storage in three different atmospheres. After storage, fruit were left to ripen for 1 and 7 days at 20 °C before instrumental and sensory measurements were performed. Data were subjected to principal component analysis (PCA) and partial least square regression (PLSR). PLSR results indicated that the parameters positively influencing acceptability were soluble solid content, titratable acidity, background colour, and emission of hexyl 2-methylbutanoate, hexyl hexanoate, hexyl propanoate, butyl 2-methylbutanoate, 2-methylbutyl acetate and butyl propanoate. Results of sensory analyses revealed the treatments considered in this work could be split into two levels of acceptability.     

广东鲜食橄榄果实质构特性比较

为比较分析广东省主要鲜食橄榄果实质构特性的差异,探讨鲜食橄榄果实质地评价的量化参数,验证感官评价质地的有效性。采用质构刺穿试验法对7个优质鲜食橄榄品种果肉质构参数和2种水肥管理方式不同成熟期的‘香甜榄’果实品质进行测定和比较分析。结果表明,不同品种之间果肉的各质构参数变异系数为12.57%~23.95%,差异性显著,与感官评价一致;果皮强度与果皮脆性和果皮韧性均呈显著正相关,果皮破裂深度与果肉硬度呈显著负相关。采用本次试验栽培管理方式可以提高橄榄完熟果实可溶性固形物6%、可滴定酸3.5%、单宁54.9%、果皮强度12.7%、果皮脆性23.5%,降低粗纤维10%、果皮韧性13.7%。果实质地品质参数主成分分析表明,果皮强度、果实硬度和纤维指数可作为质地参数量化区分不同品种间的差别,并明确果皮强度、果实硬度分别小于2300、1600 g和纤维指数大于10,为鲜食橄榄果肉质地品质较好的数值范围。研究初步建立了利用质构刺穿试验法量化评价鲜食橄榄果实质地品质的方法。     

Root traits and yield in sugar beet: identification of AFLP markers associated with root elongation rate

Morpho-physiological and molecular analysis were conducted to identify useful root indexes of sugar beet nutrient uptake capacity and productivity. Root architectural parameters, root elongation rate, sulfate uptake rate and glucose and fructose content in the root apex, traits involved in the plant response to sulfate stress, were evaluated in 18 sugar beet genotypes characterized by different root yield. Morpho-physiological traits, determined on 11-day-old seedlings grown in hydroponics under sulfate deprivation, showed variations from 59 to 197% and were significantly correlated (P < 0.01) with root yield. Under field conditions, the highest root yield genotype (L18), which has the highest root phenotypic values following sulfate shortage, also showed the greatest root length density and leaf relative water content, with respect to the lowest root yield genotype (L01). Bulk segregant analysis based on AFLP analysis, done on a segregating progeny obtained from the cross between the two lines L01 × L18, allowed the identification of two AFLP markers associated to the root elongation rate parameter that showed the highest variation among all the analyzed root traits. The genetic diversity of root adaptive traits and the use of marker-assisted selection aimed at increasing sugar yield under water and nutrient stress in sugar beet breeding programmes are discussed.     

不同桃品种的品质及加工特性评价分析

为构建不同品种桃的品质评价方法及加工特性评价体系,为桃果实的品种筛选、品质分析、贮藏加工提供参考依据,以10个品种的蒙阴蜜桃果实为试验材料,测定其感官性状、质构特性、营养品质及加工特性。结果表明,不同桃品种在感官性状、质构特性、营养品质及加工特性上存在差异,供试的10个桃品种中,白桃九号在质构特性、VC含量、糖酸比、固酸比、果汁特性等方面均具有优势,是既适合鲜食又适合加工的优良桃品种;新世纪、黄金绣的果皮硬度、可溶性固形物含量和果汁感官评分均较高,可鲜食,也可加工成果汁;黄金毛桃的可滴定酸含量较高,口感偏酸,在加工过程中需要考虑降酸以保证产品口感;寒露蜜、红焗油、黄焗油、红芙蓉的VC含量较高,可加工成高VC含量的产品;黄金蜜三号、中蟠十七口感较为软糯,但可溶性固形物和可溶性糖含量较高,甜度高,适合鲜食,同时需要注意后期的运输贮藏环节。聚类分析结果将10个桃品种分为3个类群,可根据不同果实类群特性进行加工与贮藏。