Differentiation of post harvest date fruit varieties non‐destructively using FT‐NIR spectroscopy

The world production of dates has more than doubled over the last two decades. Presently, the industrial sorting of dates is a difficult operation, affected by a high level of losses. As a consequence, the objective of this article is to study the variety discrimination capabilities of Fourier Transform‐Near Infrared (FT‐NIR) reflectance spectroscopy for post‐harvest sorting purposes. The same methodology was tested on six commercial date varieties named Estamaran, Kabkab, Mazafati, Piarom, Deglet nour and Zahedi. For each cultivar, 100 fruits were analysed using the FT‐NIR spectrometer, subsequently characterised by destructive measurements. A multivariate analysis of the FT‐NIR spectra appears a feasible tool for cultivar discrimination and even to estimate the soluble solid content (SSC) and dry matter (DM) of dates at their optimal harvesting conditions. FT‐NIR, as a non‐destructive techniques, could be a suitable way for on‐line screening of different dates varieties.     

Harvest parameters to optimise storage life of European plum 'Oullins Gage'

European plum ( Prunus domestica L.) cv. 'Oullins Gage' was harvested according to firmness on five harvest dates. Fruit was analysed at harvest and during storage for weight loss, firmness, total soluble solids (TSS), titratable acidity (TA) and skin colour before and after a 3-day shelf-life period at 20 °C. Significant differences were found among harvest dates in fruit mass, skin colour, firmness, TSS and TA. Fruit mass, TSS and colour b * increased, whereas firmness and TA decreased significantly during the harvesting period. Firmness parameter as a maximum maturity index and TSS:TA (or b * colour, a non-destructive measurement) as a minimum maturity index could be used to distinguish maturity at harvest. It is suggested that the best post-storage quality of 'Oullins Gage' plums would be obtained when fruit is harvested with TSS:TA >9 or b * colour >30, but with a firmness >20N to assure a long storage life.     

果实成熟度对南果梨近红外无损检测技术模型的影响

通过研究不同成熟度的南果梨内部化学成分含量的差异性,建立不同成熟度的南果梨可溶性固形物、酸度近红外模型,并研究模型性能的差异性,讨论成熟度的变化对南果梨近红外分析技术的影响。结果表明：在2007 年9 月13 日采收的南果梨糖、酸含量与在9 月7 日和9 月10 日采收的南果梨存在显著差异性,而7 日与10 日采收的无差异性变化;建立不同成熟度的南果梨可溶性固形物、酸度模型的相关系数都高于0.9,校正均方根误差为0.014～0.201;对模型预测能力分析表明,样品采收期在9 月13 日的模型适用范围明显高于其他两个成熟度的模型,证明成熟度的显著差异性变化,扩大了校正集样品化学成分含量的范围,进而提高了模型的适用范围。     

Quantifying the onset,rate and duration of sugar accumulation in berries from commercial vineyards in contrasting climates of Australia

Background and Aim: To predict the trajectory of sugar accumulation in berries for planning of harvest and post‐harvest operations, we derived a simple model that is consistent with the known biological and viticultural drivers of berry ripening and requires inputs that are readily available to industry. Methods and Results: We used data from three vintages in climatically contrasting regions of Australia to derive a relationship between total soluble solids (TSS) and thermal time. A linear‐plateau function was fitted to the 90th percentile data, hence providing a boundary function representing the potential for each variety‐environment combination. Biologically relevant parameters were derived including the rate of change in TSS, maximum TSS (TSS_max), the threshold thermal time when berries reached TSS_max, the onset and the duration of the period of linear increase in TSS. Gaps, calculated as the difference between actual TSS and the boundary function, correlated positively with vapour pressure. A model with the observed onset of ripening as an input and a variety and site specific rate as parameter accounted for 81–92% of the variation in TSS for independent data sets. Conclusion: The trajectory of TSS in berries can be modelled ‘as if’ the main environmental and management sources of variation affect the onset rather than the rate of sugar accumulation. Significance of the Study: Our onset‐rate model can be coupled with: (i) short‐term temperature forecasts to predict the trajectory of TSS for management purposes; and (ii) long‐term records of temperature to produce probabilistic profiles of maturity date.     

催熟对采后菠萝品质的影响与光谱识别

为探究催熟对采后菠萝品质的影响,并寻找一种快速检测品质的方法,本实验探究了催熟与未催熟菠萝采后一定贮藏期内黑心程度变化与果心、果肉和整果的可溶性固形物（total soluble solid,TSS）、可滴定酸（titratable acid,TA）质量分数变化,并探究可见/近红外光谱（visible near/ infrared spectroscopy,VIS/NIR）技术实时识别以及早期预测菠萝品质状态的可行性。菠萝采后品质变化规律表明,TSS质量分数在催熟、未催熟菠萝果肉中均最高,其次是整果,果心最低,但催熟菠萝的TSS质量分数在采摘初期高于未催熟菠萝,在贮藏过程中逐渐降低,未催熟菠萝TSS质量分数在贮藏过程中逐渐升高。催熟和未催熟菠萝的TA质量分数从高到低依次均为果肉＞整果＞果心。催熟菠萝的TA质量分数在采摘初期高于未催熟菠萝,在贮藏过程中无明显变化趋势,未催熟菠萝TA质量分数随贮藏时间延长逐渐上升。催熟与未催熟菠萝TSS/TA均为果心最高,整果和果肉其次。未催熟菠萝TSS/TA在采摘初期（第4天）大于催熟菠萝,但随贮藏时间延长逐渐降低,差异逐渐缩小。在第9天,催熟与未催熟菠萝的TSS质量分数、TA质量分数和TSS/TA均接近。VIS/NIR识别结果表明,VIS/NIR可以有效展现菠萝果实的特征信息,识别菠萝是否经过催熟处理及黑心程度,识别催熟菠萝贮藏时间（第4、5、6、7、8、9天）,识别未催熟菠萝贮藏时间（第4、5～7、8、9天）,并可预测未催熟菠萝采后第6天是否会发生黑心。本研究结果为菠萝种植与采后货架管理提供科学参考,对促进菠萝产业提升具有一定的积极意义。     

Non-destructive determination of acid–brix ratio of tomato juice using near infrared spectroscopy

Consumer's acceptance of tomato juice depends on its sourness to sweetness ratio and measuring this is important for quality control and marketing. Traditional methods destroy the samples, are time consuming and cannot be used in continuous packing or bottling systems. A non‐destructive method of quality evaluation, using near infrared (NIR) techniques, was tested, by using a portable NIR measuring unit. Spectra of tomato juice of known acid and brix values were determined and, in the wavelength range 703–1124 nm (NIR), a calibration model for acid–brix ratio (ABR) was developed, by using unscrambler software. When used to predict ABR of tomato juice statistical analysis showed minimal standard error (0.009) and satisfactorily high correlation coefficients (0.92) over the wavelength range 1059.5–1124.8 nm, for both calibration and prediction. These values were hardly different from analytical results and the NIR model has potential for non‐destructive prediction of ABR of tomato juice.     

Effect of deficit irrigation on apricot fruit quality at harvest and during storage

The effect of different irrigation strategies on the fruit quality at harvest and during storage at 1 °C of 'Búlida' apricots (Prunus armeniaca L.) was studied. Irrigation treatments consisted of a control irrigated at 100% of crop evapotranspiration (ETc) throughout the season, and two deficit irrigation treatments consisting of continuous irrigation at 50% of control, and regulated deficit irrigation (RDI) at 100% of ETc during the critical periods (second rapid fruit growth and early post‐harvest) and at 25% during the rest of the season. Fruits at harvest from both deficit irrigation treatments showed higher values of total soluble solids (TSS), titratable acidity and hue angle (h°) than control fruits, whereas their diameter, fresh weight, firmness and maturity index values were similar to those in the control. During the first 10 days of the 30‐day chilling storage period, higher TSS and h° values were found in deficit irrigated fruits, whilst the other parameters were similar for all treatments. Weight loss and fungal attacks (mainly Rhizopus sp. and Monilinia sp.) during a subsequent retail sale period of 4 days at 13 °C were the lowest in RDI. Deficit irrigation was demonstrated to be commercially advantageous for keeping fruit quality, saving considerable amounts of water. Copyright © 2007 Society of Chemical Industry     

Non‐destructive measurement of grapevine water potential using near infrared spectroscopy

Background and Aims: Near infrared (NIR) spectroscopy techniques are not only used for a variety of physical and chemical analyses in the food industry, but also in remote sensing studies as tools to predict plant water status. In this study, NIR spectroscopy was evaluated as a method to estimate water potential of grapevines. Methods and Results: Cabernet Sauvignon, Chardonnay and Shiraz leaves were scanned using an Integrated Spectronic (300–1100 nm) or an ASD FieldSpec^® 3 (Analytical Spectral Devices, Boulder, Colorado, USA) (350–1850 nm) spectrophotometer and then measured to obtain midday leaf water potential using a pressure chamber. On the same shoot, the leaf adjacent the one used for midday leaf water potential measurement was used to measure midday stem water potential. Calibrations were built and NIR showed good prediction ability (standard error in cross validation (SECV) <0.24 MPa) for stem water potential for each of the three grapevine varieties. The best calibration was obtained for the prediction of stem water potential in Shiraz (R = 0.92 and a SECV = 0.09 MPa). Conclusion: Differences in the NIR spectra were related to the leaf surface from which the spectra were collected, and this had an effect on the accuracy of the calibration results for water potential. We demonstrated that NIR can be used as a simple and rapid method to detect grapevine water status. Significance of the Study: Grapevine water potential can be measured using NIR spectroscopy. The advantages of this new approach are speed and low cost of analysis. It may be possible for NIR to be used as a non‐destructive, in‐field tool for irrigation scheduling.     

Non‐destructive measurement of vitamin C,total polyphenol and sugar content in apples using near‐infrared spectroscopy

BACKGROUND: The vitamin C and polyphenol content of apples constitute quality and nutritional parameters of great interest for consumers, especially in terms of health. They are commonly measured using laborious reference methods. The purpose of this study was to evaluate the potential of near‐infrared (NIR) spectroscopy as a rapid and non‐destructive method to determine the sugar, vitamin C and total polyphenol content in apples. RESULTS: The quality parameters of more than 150 apple genotypes were analyzed using NIR and reference methods. The results obtained using the least squares support vector machine regression method showed good to very good prediction performance. Low standard error of prediction values, in addition to relatively high ratio to prediction (RPD) values, demonstrated the precision of the models, especially for polyphenol and sugar content. High RPD values (5.1 and 4.3 for polyphenol and sugar, respectively) indicated that an accurate classification of apples based on their content could be achieved. CONCLUSION: NIR spectroscopy coupled with the multivariate calibration technique could be used to accurately measure the quality parameters of apples. In addition, in the case of breeding programs, NIR spectroscopy can be considered an interesting tool for sorting varieties according to a range of concentrations. Copyright © 2012 Society of Chemical Industry     

Deciphering the ability of different grapevine genotypes to accumulate sugar in berries

Background and Aims: To analyse the genetic determinants of berry sugar content in grapevine varieties, a method that combined measurements of total soluble solids (TSS) from berries sampled at a fixed stage after veraison with data on the yield and the leaf area was tested. Methods and Results: Over three seasons, differences in TSS at harvest for Riesling and Gewurztraminer grapes were explained by differences in the veraison dates and in the fruit‐to‐leaf ratios. TSS, yield and leaf area were also evaluated for 120 genotypes, which were progeny from a cross between Riesling and Gewurztraminer. Thermal timescales (degree‐days) proved relevant for describing sugar accumulation in the parent varieties, and when berries were sampled at a fixed heat sum after veraison in the progeny, the genotypic variability of sugar content was considerably reduced compared with the measurements on the same date at the end of the season. A negative relationship between the fruit‐to‐leaf ratio and the sugar content was also detected in the progeny. Conclusions: The evolution of TSS during berry ripening can be described using thermal timescales. Additionally, information on the yield and the leaf area needs to be integrated to analyse the behaviour of genotypes. Significance of the Study: A method to characterize the genotypic effect on fruit sugar accumulation after eliminating the contribution of veraison dates and crop load was proposed.     

Technical note: At-line prediction of mineral composition of fresh cheeses using near-infrared technologies

Milk and dairy products are important sources of macro- and trace elements for human health. However, fresh cheeses usually have a lower mineral content than other cheeses, and this makes mineral prediction more difficult. Although mineral prediction in several food matrices using infrared spectroscopy has been reported in the literature, very little information is available for cheeses. The present study was aimed at developing near-infrared reflectance (NIR, 866–2,530 nm) and transmittance (NIT, 850–1,050 nm) spectroscopy models to predict the major mineral content of fresh cheeses. We analyzed samples of mozzarella (n = 130) and Stracchino (n = 118) using reference methods and NIR and NIT spectroscopy. We developed prediction models using partial least squares regression analysis, and subjected them to cross- and external validation. Average Na content was 0.15 and 0.22 g/100 g for mozzarella and Stracchino, respectively. The NIR and NIT spectroscopy performed similarly, with few exceptions. Nevertheless, none of the prediction models was accurate enough to replace the current reference analysis. The most accurate prediction model was for the Na content of mozzarella cheese using NIT spectroscopy (coefficient of determination of external validation = 0.75). We obtained the same accuracy of prediction for P in Stracchino cheese with both NIR and NIT spectroscopy. Our results confirmed that mineral content is difficult to predict using NIT and NIR spectroscopy.     

Possibility of using near infrared spectroscopy for evaluation of bacterial contamination in shredded cabbage

The possibility of near infrared (NIR) spectroscopy to measure the amount of bacterial contamination in shredded cabbage was investigated. NIR measurements in the short wavelength region from 700 to 1100 nm were done using two types of saline solutions: one was used to stomach with the samples as the conventional method and the other was used to wash the outer surface of the sample to examine the possibility of a non‐destructive method. Partial least squares regression (PLS) was used to develop the equations for bacterial amount. Spectra from the stomacher solution and the washing solution produced similar results. Sufficiently accurate results could be obtained with the bias‐corrected standard error of prediction (SEPs) of 0.46 log CFU g^?1 for the stomacher solution and 0.44 log CFU g^?1 for the washing solution. NIR spectroscopy was clarified to be a rapid and non‐destructive method for prediction of bacterial contamination in shredded cabbage.     

甘薯水分和还原糖协同向量NIR快速检测方法

利用近红外光谱技术建立新鲜甘薯水分和还原糖含量的预测模型,实现快速检测与分析,为甘薯品质分析和种质资源筛选提供便捷。选用不同品系甘薯样品146份,109份作为校正样品,37份作为验证样品。运用不同光谱预处理方法、协同区间偏最小二乘最优波长选择法以及主成分回归和偏最小二乘法建立甘薯水分和还原糖模型。结果显示,所建甘薯水分(还原糖)最优模型的决定系数、预测均方根误差和标准差比率分别为0.974(0.885),1.154(0.270)和6.334(3.148)。表明2种模型具有较好的检测性能,近红外光谱模型的预测值与其相应的化学值有较好的相关性,适用于大批量甘薯选育时水分和还原糖含量的快速检测。     

Supervised Multivariate Analysis of Hyper-spectral NIR Images to Evaluate the Starch Index of Apples

Fruit maturity indexes are crucial in harvest time determination and commercial context. The harvest time of apples, matching the desired commercial characteristics, is assessed through starch–iodine test in practice. Fruit halves are dipped into iodine solution and patterns are visually evaluated by experts comparing them to reference charts. Aim of the work was to study the relationships of near infrared (NIR) spectral images (1,000–1,700 nm), starch/starch-free patterns visually assessed and RGB color images. Spectral images of 88 Golden Delicious Klon B apples were sampled at seven different maturity stages. Partial least-squares discriminant analysis (PLSDA) technique was used on hyper-spectral NIR images to classify single pixels using its NIR reflectance spectrum. The response variable (i.e. the classification for each pixel) was identified through the matching of single pixel obtained with the color images, segmented in two classes (starch and starch-free), and the NIR hyper-spectral matrix. Mean hyper-spectral classification obtained through PLSDA modeling on individual apple correctly classified 80.81% of the total pixels, while the unique model, i.e. a single model including all the fruits, resulted in 66.33%. In the latter case, the relationship with the RGB classification showed high values (Pearson correlation coefficient r = 0.95). The present work shows the feasibility of NIR imaging spectroscopy as a tool for apple fruit maturity determination, avoiding expert’s subjective interpretation by traditional starch index assignments.     

Loss of ascorbic acid during storage of Conference pears in relation to the appearance of brown heart

To investigate the causes of brown heart (BH) in Conference pears, the contents of ascorbic acid (AA) and dehydroascorbic acid (DHAA) in fruits were studied during the first period of storage. AA was studied in 1999 and 2000, DHAA in 1999 only. Pears from normal and very late harvest stored immediately or after a delay in a controlled atmosphere with 2% O₂ and low (0.7%) or high (5%) CO₂ were compared. DHAA content did not change during storage in any treatment. AA decreased in storage according to an exponential model. The rate of AA loss was different in the two years and was higher in late‐harvest fruits and in those stored in 5% CO₂. BH appeared in different treatments when AA decreased below a threshold, which was about 2 mg kg^?1 fresh weight, corresponding to 5% of the AA content at harvest. The frequency and severity of symptoms depended linearly on the time spent by fruits in low‐ascorbate conditions. Advanced maturity at harvest and storage in high CO₂ determine the appearance of BH and increase the rate of AA loss, probably through a reduction in the turnover of antioxidants. © 2002 Society of Chemical Industry     

On-line prediction of fresh pork quality using visible/near-infrared reflectance spectroscopy

Visible/near-infrared (Vis/NIR) spectroscopy was tested to predict the quality attributes of fresh pork (content of intramuscular fat, protein and water, pH and shear force value) on-line. Vis/NIR spectra (350–1100 nm) were obtained from 211 samples using a prototype. Partial least-squares regression (PLSR) models were developed by external validation with wavelet de-noising and several pre-processing methods. The 6th order Daubechies wavelet with 6 decomposition levels (db6–6) showed high de-noising ability with good information preservation. The first derivative of db6–6 de-noised spectra combined with multiplicative scatter correction yielded the prediction models with the highest coefficient of determination (R²) for all traits in both calibration and validation periods, which were all above 0.757 except for the prediction of shear force value. The results indicate that Vis/NIR spectroscopy is a promising technique to roughly predict the quality attributes of intact fresh pork on-line.     

Temperature sums experienced before harvest partially determine the post‐maturation juicing quality of oranges grown in the Murrumbidgee Irrigation Areas (MIA) of New South Wales

Fruit acid levels are important to maturity standards for both fresh fruit and juice acceptability for processing oranges. Citrus fruit maturity standards are based on sweetness (Brix), titratable acidity (% acid) and their ratio. Harvest of Navel oranges for fresh juice can extend for up to 3 months (August–October) and for as long as 7 months (November–June) for Valencia oranges after they first reach acceptable fresh market maturity. Juice processors encourage ‘late hanging’ of fruit on trees to secure a continuous supply of fresh juice. During this time, gradual changes occur in % acid, Brix and juice content. This study tested the hypothesis that a significant proportion of the variation in fruit quality late in the harvest season could be accounted for by environmental conditions during the period that the fruits were left on the trees. Fruit juice quality was assessed in terms of Brix and % acid at the time of harvest for 19 000 fruit deliveries during a 9 year period from 1988 to 1996. The relationship between quality (Brix and acid content) and temperature sums (effective heat units—EHUs) for the period the fruits were held on the trees was tested. A temperature sum (‘day degree’) model for predicting relative changes in acid and Brix content of late‐harvested fruit was developed for both Valencia and Navel oranges. The juice acid relationship with EHUs was stronger than the Brix relationship with EHUs. In addition, the seasonal ‘behaviour’ of % acid was more consistent than that of Brix in both Valencia and Navel oranges. A linear reduction in % acid with increasing EHUs was evident in both varieties. Estimates of fruit quality (Brix/acid ratio) at harvest time should be made using the equations describing changes in % acid with EHUs and the relationship between Brix and % acid to determine Brix. These equations have potential use in predicting the internal quality of citrus fruit during extended harvest periods. EHU‐based fruit quality estimates could determine harvest schedules that enable growers to achieve the optimum factory price for their fruit whilst maximising returns to processors through more efficient product utilisation. © 2000 Society of Chemical Industry     

Quality Characterization of Celery (Apium graveolens L.) by Plant Zones and Two Harvest Dates

Abstract: The aim of this study was to characterize the quality of celery petioles (Apium graveolens L. cv Golden Clause) from the external, middle, and internal zones of each plant. Harvest dates were 93 (HD1) and 124 (HD2) days after transplantation. Total weight (TW), total length (TL), total leaves number (LN), and petiole length of leaves (PL) for the 3 zones were measured. Physicochemical (color, b* and h; texture; total soluble solids, TSS; titratable acidity, TA; water content, WC), nutraceutical (ascorbic acid, AA; total quinones, TQ; browning potential, BP), and sensorial analysis (flavor, fibrosity, crunchiness) were done at harvest on petioles of each zone. No differences between harvesting dates were found in TW, TL, LN, and PL. Middle leaves had the highest PL. Harvest dates were not different in b*, h, TA, AA, and WC. Texture, TSS, BP, and TQ resulted higher in petioles of HD2 than in HD1. Similar TSS and TA were found in leaves of different plant zones. The yellow color of both external and internal zones was significantly higher than in the middle zone. The texture and BP was similar between the external and middle zones but the WC was lower in the external zone. Similarly, the AA content as well as the TQ was also lower than in the middle zone. Harvest delay improved the nutraceutical value in terms of BP and TQ, even though it also resulted in pithiness and fibrosity of the leaves. This study therefore suggests that the petioles of the middle zone when harvested at HD1 are the most suitable for consumption. Practical Application: Celery is a vegetable reduced in calories, has a high nutritional value and its fresh petioles are mainly consumed in salads. The texture and flavor are the most important attributes that define consumers’ acceptability. As nutritional value, texture, and flavor may change with plant age and different zones of the plant, harvest date plays an important role on quality. Results indicate that harvest delay improved the nutraceutical value even though it also resulted in pithiness and fibrosity of the stalks. Petioles of the middle zone, when harvested at 93 d after transplanting, are the most suitable for consumers’ consumption.