Miniature handheld NIR sensor for the on-site non-destructive assessment of post-harvest quality and refrigerated storage behavior in plums

This study evaluated the feasibility of using a handheld micro-electro-mechanical system (MEMS) spectrometer working in the 1600–2400 nm range for the measurement of quality-related parameters (soluble solid content, firmness, variety and post-harvest storage duration under refrigeration) in intact plums. Spectroscopic measurements were also made for each fruit using a diode-array Vis–NIR spectrophotometer (400–1700 nm) for purposes of comparison. A total of 264 plums (Prunus salicina L.) cv. ‘Black Diamond’, ‘Golden Globe’, ‘Golden Japan’, ‘Fortune’, ‘Friar’ and ‘Santa Rosa’, received and stored at 0 °C and 95% RH for 9 days, were used to build calibration models using different spectral signal pre-treatments and the modified partial least squares regression method. The two NIR instruments evaluated provided good precision, although the diode-array instrument yielded slightly greater precision for soluble solid content; statistic values were r² = 0.73 and the standard error of cross validation (SECV) = 1.11% for calibration, and r² = 0.68 and the standard error of prediction (SEP) = 1.22% for validation. Firmness measurements were less precise in both instruments, though again slightly better in the diode-array instrument: r² = 0.64 and SECV = 1.77 N for calibration; and r² = 0.61 and SEP = 2.30 N for validation, respectively. The performance of the two instruments for classifying plums by variety and by refrigerated post-harvest storage duration (0, 6 and 9 days) was evaluated using partial least square-discriminant analysis. A total of 96.5 % of samples were correctly assigned to their variety, while 94.5 % of plums were correctly assigned to their refrigerated storage day. In general, promising results were obtained with both instruments, with similar levels of accuracy for the measurements for soluble solid content, variety and refrigerated storage duration; the prediction model developed using the diode-array spectrophotometer provided better results for firmness.     

Texture Prediction in Intact Green Asparagus by Near Infrared (NIR) Spectroscopy,Assaying Linear and Non-linear Regression Strategies

Texture-related parameters were assessed in intact green asparagus at harvest and during postharvest storage using near-infrared spectroscopy combined with MPLS and LOCAL algorithms. Three spectrophotometers were evaluated for this purpose: a monochromator (range, 400–2,500 nm), a diode-array Vis–NIR spectrophotometer (range, 400–1,700 nm), and a handheld micro-electro-mechanical system (MEMS) spectrophotometer (range, 1,600–2,400 nm). Three hundred green asparagus spears (cv. “Grande”) were used to obtain calibration models based on reference data and NIR data. Results for maximum shear force showed that LOCAL algorithm improved the predictive capacity of models constructed using all three NIRS instruments, increasing r ² by 24, 16, and 56 % and reducing the SEP(c) values by 11, 8, and 14 %, respectively. For cutting energy, the LOCAL also improved the predictive capacity of the models (r ² increased by 3 % for the monochromator and the diode-array instrument and by 6 % for the MEMS device; and the SEP(c) decreased by 3 % in the three instruments). It is worth noting that while the monochromator and diode-array instruments displayed similar predictive capacity for the parameters tested, the MEMS instrument achieved slightly poorer results but has clear advantages for the measurement of texture in intact asparagus, being economical, portable, and easy to use in situ.     

Non-destructive characterization and quality control of intact strawberries based on NIR spectral data

External and internal quality parameters of strawberries (Fragaria x ananassa Duch.) were studied at harvest and during postharvest refrigerated storage using a handheld micro-electro-mechanical system (MEMS) near-infrared spectrophotometer. A total of 189 strawberry punnets were used to develop calibration models using various spectral signal pretreatments and linear and non-linear regression algorithms; the sampling unit for both NIRS analysis and reference methods comprised 5 strawberries from each punnet. Modified partial least squares analysis confirmed the feasibility of NIRS for predicting color-related external quality parameters (L^∗, a^∗ and C^∗) as well as firmness, soluble solid content and titratable acidity. For other tested parameters (b^∗, h^∗ and pH), the results suggested that NIRS prediction was not feasible. However, the application of a LOCAL algorithm considerably improved the ability of models to predict all the internal quality parameters studied. Use of the LOCAL algorithm proved valuable in minimizing the error in NIRS models for predicting complex internal quality parameters, mainly those related to texture and acidity. Subsequently, the ability of NIR technology to classify individual strawberries as a function of variety was tested using partial least squares discriminant analysis (PLS-DA), which yielded percentages of correctly classified samples (ratio of correctly classified samples to total samples) ranging from 57% for the Camarosa variety to 78% for Antilla Fnm.     

Control of post‐harvest brown rot on nectarine by Epicoccum nigrum and physico‐chemical treatments

Post-harvest physico-chemical treatments—water at 40 °C or 60 °C (HW), and sodium bicarbonate at 1 or 2.5% (SBC) at 20, 40 and 60 °C—were tested on peaches and nectarines in order to control brown rot caused by Monilinia spp. and to select the best physico-chemical treatment to be used in combination with pre-harvest applications of the biological control agent Epicoccum nigrum (ATCC number 96794). Experiments were carried out in France, Italy and Spain in order to test different experimental conditions. Monilinia rot was reduced in peach and nectarine treated with HW (40 °C for 2 min) in all three countries, the percentage of rot reduction was similar for France, Italy and Spain (over 40%). A synergistic effect between HW at 40 °C during 150 s or at 60 °C during 20 s and SBC was observed in all three countries. After preliminary experiments post-harvest treatment of HW (60 °C) + SBC (1%) during 20 s was selected to combine it with field treatments. Pre-harvest treatments with fungicide or E. nigrum did not reduce brown rot in any country. However, pre-harvest treatments with E. nigrum, chemical fungicide, and their integration followed by post-harvest physico-chemical treatment significantly reduced Monilinia rot compared to pre-harvest untreated fruits followed by post-harvest physico-chemical treatment in Italy (over 70%). Post-harvest treatments with E. nigrum were also tested in Italy on natural and artificial infections in nectarine over 3 years. E. nigrum, as fresh or formulated cells, at a concentration of 10⁸ conidia mL⁻¹ were effective, significantly reducing the incidence of brown rot compared to control, both under artificial and natural infection, from 43 to 100%. Copyright © 2007 Society of Chemical Industry     

采前壳寡糖处理对杏果实贮藏品质的影响

以新疆赛买提杏为试材,在杏的坐果期、膨大期、转色期及采收前48 h用分子量为5000浓度分别为0.01%、0.05%、0.25%的壳寡糖溶液喷施杏树,采收后的杏果实贮藏在温度为4℃、相对湿度90%~95%的冷库中,定期测定杏果实的品质指标,研究采前壳寡糖处理对杏果实贮藏品质的影响。实验结果表明:0.05%浓度壳寡糖处理效果最好,能有效地抑制杏果实贮藏期间的发病率,保持杏果实的硬度和叶绿素含量,降低杏果实的失重率,延缓抗坏血酸和可滴定酸含量的降低和可溶性固形物含量的上升。     

Duroc and Iberian pork neural network classification by visible and near infrared reflectance spectroscopy

Visible and near infrared reflectance spectroscopy (VIS/NIRS) was used to differentiate between Duroc and Iberian pork in the M. masseter. Samples of Duroc (n = 15) and Iberian (n = 15) pig muscles were scanned in the VIS/NIR region (350–2500 nm) using a portable spectral radiometer. Both mutual information and VIS/NIRS spectra characterization were developed to generate a ranking of variables and the data were then processed by artificial neural networks, establishing 1, 3, or 10 wavelengths as input variable for classifying between the pig breeds. The models correctly classified >70% of all problem assumptions, with a correct classification of >95% for the three-variable assumption using either mutual information ranking or VIS/NIRS spectra characterization. These results demonstrate the potential value of the VIS/NIRS technique as an objective and rapid method for the authentication and identification of Duroc and Iberian pork.     

Potential for mycotoxin-producing fungal growth in various agro-ecological settings and maize storage systems in southwestern Ethiopia

The objective of this study was to evaluate the potential growth of mycotoxin-producing fungi under different agro-ecological settings and storage methods in southwestern Ethiopia. The districts of Sokoru, Omonada, and Dedo, representing three agro-ecological settings, were considered for the study. Six farmers' fields were selected from each agro-ecology for monitoring pre-harvest weather conditions, while three farmers' and three collectors' storage systems were considered for post-harvest study. Additional warehouses were also included for current study. Fungal pathogens were isolated and identified once per month over a six-month storage period. Both long-term climate and pre-harvest weather data indicated that all agro-ecological conditions were conducive to the growth of the target fungal species. Temperatures inside the farmers' storage systems showed significant (P = 0.04) positive correlations with ambient conditions. Significant (P < 0.05) positive correlations were also observed between the relative humidity under the farmers' storage and the ambient conditions. In contrast, there were no significant correlations between the collector's storage and ambient conditions for either temperature or relative humidity. A simple linear regression model revealed that there was a negative relationship between frequency of mycotoxin-producing fungi and the temperature inside the farmers' storage systems; whereas, fungal occurrence was positively and significantly (P < 0.05) correlated with the relative humidity. Both temperature and humidity were associated with fungal frequency of occurrence in the collectors' store-houses and the wholesalers' warehouses. The farmers' traditional storage methods are not climatically controlled to maintain post-harvest product quality. Therefore, a simple and accessible climate-controlled storage structure is necessary for the resource-poor growers of the study area.     

In-situ Iberian pig carcass classification using a micro-electro-mechanical system (MEMS)-based near infrared (NIR) spectrometer

Iberian pig (IP) products are gourmet foods highly appreciated at international markets, reaching high prices, because of its exquisite flavors. At present, there aren't practical and affordable analytical methods which can authenticate every single piece put on the market. This paper reports on the performance of a handheld micro-electro-mechanical system (MEMS)-based spectrometer (1600-2400 nm) for authentication-classification of individual IP carcasses into different commercial categories. Performance (accuracy and instrumental design) of the instrument was compared with that of high-resolution NIRS monochromators (400-2500 nm). A total of 300 carcasses of IPs raised under different feeding regimes (“Acorn”, “Recebo” and “Feed”) were analyzed in three modes (intact fat in the carcass, skin-free subcutaneous fat samples and melted fat samples). The best classification results for the MEMS instrument were: 93.9% “Acorn” carcasses correctly classified, 96.4% “Feed” and 60.6% “Recebo”, respectively. Evaluation of model performance confirmed the suitability of the handheld device for individual, fast, non-destructive, low-cost analysis of IP carcasses on the slaughterhouse line.     

采前水杨酸处理对树莓果实贮藏效果及抗氧化能力的影响

探讨采前水杨酸处理对树莓果实贮藏效果以及抗氧化能力的影响。树莓果实于采前用1mmol/L 水杨酸喷施1 次、2 次和3 次后,采摘并贮藏于1℃条件下,分别隔10、23d 统计好果率,同时测定清除自由基的能力并研究总酚、总黄酮和花青素含量的变化规律。结果表明水杨酸喷施2～3 次均能显著提高树莓采后贮藏期间的好果率,其中喷施2 次的效果最好。采前水杨酸处理可提高采摘时树莓果实花青素、总酚和总黄酮的含量,以及总抗氧化能力、羟自由基和DPPH 自由基清除能力,而显著降低过氧化氢含量,以喷施2 次效果最为明显。同时,水杨酸处理可提高树莓果实采后贮藏期间的过氧化氢、总黄酮含量和清除DPPH 自由基的能力,降低花青素和总酚含量、以及总抗氧化能力和清除羟自由基能力。采前水杨酸处理主要通过诱导次生代谢物质产生和增强清除DPPH 自由基能力来显著提高树莓果实采后贮藏效果。     

采前和采后贮藏对果蔬中抗氧化物质影响的研究进展

自由基是人体正常代谢的产物, 但自由基过量会引发一系列的疾病。越来越多的研究表明, 食用果蔬有助于预防由过量自由基引起的多种疾病, 这主要源于果蔬中富含的各种抗氧化物质。本文主要从采前和采后贮藏保鲜两个阶段对果蔬组织中的抗氧化物质(重点包括总酚、总黄酮、抗坏血酸、花青素)以及抗氧化能力的影响因素及其影响效果进行了较为全面的综述。     

果实采前套袋对热带亚热带果树果实品质和耐贮性的影响

果实采前套袋是提高果品的品质和商品价值的有效方式。本文综述了热带、亚热带果树果实采前套袋的研究进展与应用现状,果实采前套袋对果实品质、农药残留、重金属含量、成熟期和采后果实耐贮性的影响,同时指出了果实采前套袋存在的问题和今后需进一步研究的领域。     

采前水杨酸处理对杏果实抗病性及苯丙烷代谢的诱导

以新疆赛买提杏为试材,在果实坐果期、膨大期、转色期及采收前48 h的4 个时期,采用1.0 mmol/L水杨酸对杏果实进行喷施处理,以喷清水处理作为对照。采收后的杏果实置于4 ℃、90%～95%相对湿度条件下贮藏,定期统计杏果实接种链格孢（Alternaria alternata）的病斑直径和接种发病率,测定苯丙氨酸解氨酶（PAL）、肉桂酸羟化酶（C4H）、4-香豆酰-辅酶A连接酶（4-CL）的活性及木质素、总酚和类黄酮的含量,研究采前水杨酸处理对杏果实抗病性和苯丙烷代谢关键酶活性及代谢产物积累的影响。结果显示：采前水杨酸处理能有效降低杏果实损伤接种的病斑直径和接种发病率,显著提高杏果实PAL、C4H、4-CL的活性和木质素、总酚、类黄酮的含量。     

不同采后处理对云南油桃和水蜜桃的贮藏保鲜效果对比

为探索延长云南油桃和水蜜桃保鲜期的方法,以云南文山黄金油桃和红蜜桃为试材,研究了1-MCP、ClO2、2种涂膜处理对黄金油桃和红蜜桃两种桃贮藏保鲜效果,结果表明:虽然1-MCP处理对两种桃L*、a*值和b*值的维持均有效果,但云南黄金油桃和红蜜桃适宜的采后处理方法不同;1-MCP处理的黄金油桃色差值最高,贮藏25d,L*、a*值和b*均维持较高,相对电导率值最低(54.43%),质量损失率较低(1.05%),TSS含量为16.27%最高,表明1-MCP处理是较适宜黄金油桃贮藏保鲜的处理。ClO2处理有利于红蜜桃外观的维持,贮藏25 da*值和b*值均高于其他处理,且具有最低的质量损失率和最高的TSS含量,相对电导率值为55.81%,低于1-MCP处理;表明ClO2处理是较适宜红蜜桃的采后处理。     

Comparison of visible and near infrared reflectance spectroscopy to discriminate between pasture-fed and concentrate-fed lamb carcasses

We compared visible and near infrared spectroscopy to distinguish pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 120 P and 139 S lambs were used. The reflectance spectrum of perirenal fat was measured at wavelengths between 400 and 700 nm using a portable spectrophotometer, and at wavelengths between 400 and 2500 nm using a laboratory monochromator NIRSystem. In method W_450–510, the reflectance data were used at wavelengths between 450 and 510 nm. In methods W_400–700 and W_400–2500, a multivariate analysis was performed over the full set of reflectance data, at wavelengths in the range 400–700 nm and 400–2500 nm, respectively. The proportion of correctly classified P lambs was 89.1%, 90.8% and 97.5% for W_450–510, W_400–700 and W_400–2500, W_400–2500 performing best. The proportion of correctly classified S lambs was not significantly different between methods (98.6%, 98.6% and 97.8% for W_450–510, W_400–700 and W_400–2500, respectively).     

Preservation treatment of fresh raspberries by e-beam irradiation

E-beam irradiation was studied as a post-harvest treatment for red raspberries (Rubus idaeus L.). Microbial inactivation (natural microbiota and potential pathogenic bacteria) and bioactive properties (phenolic content, vitamin C content and antioxidant activity and cytotoxicity) of these fruits were evaluated before and after irradiation and during storage of 14 days at 4 °C. A reduction of 2 log CFU/g of mesophilic bacteria and 3 log CFU/g on filamentous fungi, and no detection of foodborne inoculated pathogens (3 log CFU/g) was achieved with an e-beam treatment at 3 kGy and during 7 days of refrigerated storage. Regarding bioactive properties, the results suggested that irradiation could preserve the phenolic content and antioxidant activity of raspberries through 7 days of cold storage, even though a decrease of 80% on ascorbic acid concentration was observed. Furthermore, no in vitro inhibitory effect on human cells lines was observed for the extracts from e-beam-treated raspberries. The overall results suggested that use of e-beam irradiation as post-harvest treatment of raspberries as an emergent, clean and environmental friendly process to extend the shelf-life of this fruit with safety and preservation of bioactivity.Industrial relevanceRed raspberries are known to demonstrate high bioactivity that could be beneficial to human health, but are highly perishable and often associated with foodborne outbreaks, which makes its safety and commercialization a challenge. The use of a terminal control such as irradiation might reduce the burden of disease transmission and extend the quality of fresh red raspberries. The present research indicated that e-beam irradiation can be used as post-harvest treatment of raspberries, guarantying its safety and quality with the add-value of shelf-life extension.     

Comparison of visible and near infrared reflectance spectroscopy to discriminate between pasture-fed and concentrate-fed lamb carcasses

We compared visible and near infrared spectroscopy to distinguish pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 120 P and 139 S lambs were used. The reflectance spectrum of perirenal fat was measured at wavelengths between 400 and 700 nm using a portable spectrophotometer, and at wavelengths between 400 and 2500 nm using a laboratory monochromator NIRSystem. In method W_450–510, the reflectance data were used at wavelengths between 450 and 510 nm. In methods W_400–700 and W_400–2500, a multivariate analysis was performed over the full set of reflectance data, at wavelengths in the range 400–700 nm and 400–2500 nm, respectively. The proportion of correctly classified P lambs was 89.1%, 90.8% and 97.5% for W_450–510, W_400–700 and W_400–2500, W_400–2500 performing best. The proportion of correctly classified S lambs was not significantly different between methods (98.6%, 98.6% and 97.8% for W_450–510, W_400–700 and W_400–2500, respectively).     

Reduction of Postharvest Decay of Peach and Nectarine Caused by Monilinia laxa Using Hot Water Dipping

The effect of hot water dipping (HWD) at 40, 44 and 48 °C for 6 and 12 min on germination of conidia of brown rot fungus (Monilinia laxa) in vitro and the effect of HWD at 48 °C for 6 and 12 min on the fruit quality and development of M. laxa on peach cv. “Roig” and nectarine cv. “Venus” after artificial inoculation in cold storage were studied. Temperature and duration of treatment significantly affected germination of conidia. After HWD at 48 °C for 12 min, the lowest germination of conidia (9%) was recorded, which was more than 10 times lower than control (93%). After 3 days from inoculation, there were 80% of inoculated spots with visual symptoms of decay caused by M. laxa on control peaches and 40% of such spots on control nectarines. Successful infections were recorded on only 5% of inoculated spots of nectarine and 10% of inoculated spots of peach after HWD at 48 °C for 12 min. HWD at 48 °C for 12 min significantly decreased titratable acidity and increased soluble solids concentration/titratable acidity ratio in nectarines. No visual symptoms of heat damage were found on fruits as a consequence of any of the studied treatments. The results show that it is possible to control postharvest brown rot (M. laxa) on peach using HWD at 48 °C for 12 min and on nectarine using HWD at 48 °C for 6 min without a significant loss of fruit quality.     

Prediction of fatty acids content in pig adipose tissue by near infrared spectroscopy: At-line versus in-situ analysis

A handheld micro-electro-mechanical system (MEMS) based spectrometer working in the near infrared region (NIR) (1600–2400 nm) was evaluated for in-situ and non-destructive prediction of main fatty acids in Iberian pig (IP) carcasses. 110 IP carcasses were measured. Performance of the instrument was compared with at-line high-resolution NIRS monochromators working in two analysis modes: melted fat samples (transflectance cups) and intact adipose tissues (interactance fiber optic). Standard Error of Prediction (SEP) values obtained on the MEMS-NIRS device were: 0.68% (stearic), 1.30% (oleic), 0.55% (linoleic) and 1% (palmitic), explaining a variability of 83%, 84%, 81% and 78%, respectively. As expected, this represented a loss of predictive capability in comparison to at-line models, even with the same spectral characteristics as on the handheld device. However, the estimated total errors were at the same level for gas chromatography and NIRS analysis. This indicates that the MEMS-NIRS in-situ analysis of each individual carcass provides a cost-effective and real-time quality control system with suitable accuracy.     

On-Site NIR Spectroscopy to Control the Shelf Life of Pork Meat

Control of meat shelf-life includes the time that it remains in the exhibitor of sale (such as the supermarket) until its rejection for the consumer, or withdrawal due to expiry date. Near infrared spectroscopy (NIRS) is one of the most promising techniques for large-scale meat quality control. This study investigated the potential of on-site NIRS portable instrumentation-based models to predict three microbiological parameters to establish if pork meat is acceptable or not for consumption (aerobic Mesophilous microorganisms, Enterobacteriaceae, and lactic acid bacteria) and pH to quality control food preservation and shelf-life extension on intact slices of pork meat packaged under two different modified atmospheres. NIR calibrations were developed by using an on-site Phazir instrument (Polychromix, Wilmington, MA, USA) in the range 1,600–2,400 nm. A total of 252 samples of pork meat slices were directly scanned twice in reflectance mode on trays, once before and another one after removing the film cover at 1, 3, 5, 7, 9, 12, and 15 days of storage. Results showed that spectra of meat acceptable or not for consumption have marked differences around 1,660 nm. NIRS quantitative prediction models showed r ² values between 0.19 and 0.65 for the microbiological parameters assayed. The developed NIRS methodology makes possible on-site prediction of microbiological status of pork meat with a standard error of cross-validation around 1 log cfu/g. Results have shown that modified atmosphere packaging has no influence on calibration statistics.     

不同浓度赤霉素处理对油桃保鲜效果的影响

以油桃为试材,用浓度为150mg／kg、200rag／kg、250mg／kg的赤霉素溶液涂膜处理30min,定期测定油桃果实的各项指标,研究赤霉素对油桃保鲜效果的影响。结果表明,经过赤霉素溶液涂膜处理,有效地减轻了油桃果实的失重现象、推迟了呼吸跃变出现时间、延缓了糖分和VC损失,有防止腐烂、保持硬度作用;对含酸量影响不大,其中浓度为200mg／kg的赤霉素溶液对油桃果实进行涂膜处理保鲜效果最好,能够较长时间的保持油桃果实的贮藏品质。