Nondestructive Brix Evaluation of Apples of Different Origin Using Near Infrared (NIR) Filter Based Reflectance Spectroscopy

Abstract

A filter based near infrared (NIR) technique to evaluate Brix value, in a non destructive way, of Indian apples, along with apples from other countries, has been investigated here. Reflectance characteristics at ten NIR wavelengths were recorded by in-house developed probe for five Indian varieties and four imported varieties. A separate calibration and validation set for each variety was formed. Brix values of the calibration and validation sets of apples were evaluated with a refractometer from Bellingham and Stanley, Model 840. Principal component regression was used to generate calibration and prediction of Brix for the validation set. It was found that Brix values of all varieties of apples can be predicted with a standard error of prediction, 0.7322–1.7809, while root mean square error is also in the same range. It was further noticed that reduction in data recording wavelength leads to an increase in SEP and RMSE.     

A comparative study of the physico‐chemical properties affecting the organoleptic quality of fresh and thermally treated yellow tomato ecotype fruit

In recent years, yellow commercial tomatoes have attracted great interest from consumers. The goal of this work was to characterise the parameters of three yellow genotypes that affect the fruit quality, in comparison with those of a red fruit genotype. Compared to the other genotypes, the GiaGiù ecotype was characterised as having the highest titratable acidity, organic acids content and pectin content before and after a thermal treatment simulating industrial pasteurisation. Most of the analysed parameters influence the taste and aroma of fresh fruit and processed products, particularly the high glutamic acid content measured in the GiaGiù ecotype. This genotype was also distinctive for its higher pectin content, which influences the texture. These features might allow the development of new food products that require a specific viscosity, such as sauces and ketchup. Interestingly, the beneficial properties of GiaGiù were preserved after thermal processing.     

折射仪法快速检测卷烟的白利糖度

白利糖度的检测被广泛的应用于水果、蔬菜等食品行业,本文首次将其应用于烟草行业的检测。建立采用折射仪法快速测定卷烟白利糖度的方法,并对不同样品的白利糖度进行了比较。结果表明:烤烟型卷烟的白利糖度最高,混合型卷烟次之,最低的为雪茄型卷烟。真伪卷烟的白利糖度具有显著性差异,真品卷烟的白利糖度均高于假冒伪劣卷烟。因此,白利糖度检测可以作为卷烟真伪鉴别的一种辅助手段。     

近红外光谱法快速分析甲糖膏的应用研究

研究应用近红外光谱法快速分析甘蔗制糖生产中甲糖膏的锤度和蔗糖分。采用NIRSystems 6500型近红外多功能分析仪,对采自生产线的甲糖膏进行光谱扫描和测定,用时小于2min。锤度和蔗糖分模型的光谱预处理方法以"SNV+Detrend、一次求导和一次平滑联合处理"效果最佳,改进型偏最小二乘法建立的模型效果最佳。锤度模型的SEC为0.522,SEP为0.96;蔗糖分模型的SEC为0.576,SEP为0.86。锤度和蔗糖分的偏差都小于1,满足糖厂要求,近红外光谱法应用在甲糖膏锤度和蔗糖分的快速测定是可行的。     

Visible/near infrared-partial least-squares analysis of Brix in sugar cane juice: A test field for variable selection methods

Several variable selection algorithms were applied in order to sort informative wavelengths for building a partial least-squares (PLS) model relating visible/near infrared spectra to Brix degrees in samples of sugar cane juice. Two types of selection methods were explored. A first group was based on the PLS regression coefficients, such as the selection of coefficients significantly larger than their uncertainties, the estimation of the variable importance in projection (VIP), and uninformative variable elimination (UVE). The second group involves minimum error searches conducted through interval PLS (i-PLS), variable-size moving-window (VS-MW), genetic algorithms (GA) and particle swarm optimization (PSO). The best results were obtained using the latter two methodologies, both based on applications of natural computation. The results furnished by inspection of the spectrum of regression coefficients may be dangerous, in general, for selecting informative variables. This important fact has been confirmed by analysis of a set of simulated data mimicking the experimental sugar cane juice spectra.     

Short communication: Comparative estimation of colostrum quality by Brix refractometry in bovine,caprine, and ovine colostrum

Newborn ungulates depend on the timely supply of colostrum containing sufficient immunoglobulins to obtain passive immunity against disease. Brix refractometry enables a rapid on-farm estimation of colostrum quality and has been intensively studied in bovines. However, the suitability of Brix refractometers for assessing colostrum quality in goats and ewes has been scarcely evaluated. The present study compared bovine, caprine, and ovine colostrum quality estimation using an optical Brix refractometer. In addition, between-species variations in the relationships between Brix values and colostrum constituents (IgG, fat, protein, and lactose) and the accuracy of Brix refractometry at different cutoff values were evaluated by a receiver operating characteristic curve analysis. We measured the Brix value and contents of IgG, fat, protein, and lactose in 324 colostrum samples (108 cows, 116 does, and 100 ewes). Thresholds for classification of good colostrum quality (as determined by ELISA) were set at 50 mg IgG/mL in cows and 20 mg/mL in does and ewes. Bovine colostrum showed the greatest IgG concentrations compared with caprine and ovine colostrum. Fat and protein content was higher in sheep colostrum compared with the other species, whereas the highest lactose concentrations were detected in goat colostrum. Brix values ranged from 11.4 to 34.6% (22.1 ± 4.2%; mean ± standard deviation), 15.4 to 40.0% (28.5 ± 6.8%), and 8.8 to 39.8% (21.6 ± 5.3%) in bovine, ovine, and caprine colostrum, respectively. In all 3 species, Brix was highly correlated with IgG and protein concentrations (cows, r = 0.83 and 0.98; goats, r = 0.83 and 0.89; sheep, r = 0.75 and 0.87). Optimal cutoff points for greatest accuracy of Brix measurements were 19.3% Brix in cows [with 87.1% sensitivity (Se) and 100% specificity (Sp)], 20.7% Brix in does (with 53.5% Se and 100% Sp), and 26.5% Brix in ewes (with 75% Se and 91.3% Sp). In conclusion, Brix refractometry is an acceptable tool for on-farm estimations of colostrum quality in does and ewes despite distinct between-species variations in colostrum composition.     

Analysis of phenotypic variation of sugar profile in different peach and nectarine [Prunus persica (L.) Batsch] breeding progenies

BACKGROUND: Specific sugar contents are well known for contributing to a range of quality traits of fresh fruits such as flavour, texture and health properties. Peaches and nectarines of 205 genotypes from 14 different breeding progenies cultivated under Mediterranean conditions were evaluated by high‐performance liquid chromatography for their content of these sugar traits. RESULTS: A high contribution of cross to the phenotypic variance of all evaluated fruit quality traits was found. There were significant differences in mean sugar concentrations between peach and nectarine, yellow‐ and white‐fleshed or freestone and clingstone genotypes. Pre‐selected genotypes from the original breeding programme showed enhanced soluble solid content (SSC), total sugar and sucrose contents. A significant effect of year was found for SSC, sucrose and glucose contents, whereas no effect was found for fructose and sorbitol contents. Individual sugar contents correlated significantly with each other and with other fruit quality traits. CONCLUSION: A significant effect of cross, year and qualitative traits on the sugar profile of peaches and nectarines was found. Moreover, the differences shown in sugar traits between the breeding population and the pre‐selected genotypes indicated the importance of sugar profile in the global quality of peaches and nectarines. Copyright © 2009 Society of Chemical Industry     

A herd-level study on colostrum management factors associated with the prevalence of adequate transfer of passive immunity in Québec dairy herds

The objective of this study was to identify herd-level colostrum management factors associated with the adequate transfer of passive immunity (TPI; defined as serum Brix refractance ≥8.4% in the first week of life). A total of 59 commercial Holstein dairy farms were included in this observational cross-sectional study. In every participating herd, a minimum of 14 Holstein calves were sampled to measure their TPI using a digital Brix refractometer. Colostrum samples fed to each of these calves were collected to estimate IgG concentration (colostrum quality) using a digital Brix refractometer and bacterial contamination using the Petrifilm (3M, St. Paul, MN) culture system. Dairy producers completed a questionnaire on colostrum management to assess on-farm practices. The study outcome was the prevalence of adequate TPI calculated based on the proportion of adequate TPI (defined with an individual threshold ≥8.4% Brix) on the total samples tested within each herd. According to the threshold determined in a previous study investigating the influencing colostrum management factors to achieve adequate TPI at the calf level, the prevalence of an adequate colostrum volume fed at first meal (≥2.5 L), the prevalence of adequate colostrum quality (≥24.5% Brix), the prevalence of an adequate time to first feeding (delay between birth and the first colostrum meal, ≤3 h), the prevalence of low aerobic bacterial contamination (≤20,000 cfu/mL), the prevalence of low coliform contamination (≤1,000 cfu/mL), and the prevalence of females were calculated. The herd-level prevalence of adequate TPI ranged from 24% to 100%, with a median of 68%. The median herd prevalences of an adequate colostrum volume fed at first meal, of adequate colostrum quality, of an adequate time to first feeding, of low aerobic bacterial contamination, of low coliform contamination, and of females, were 71, 42, 41, 64, 88, and 61%, respectively. In the final model, the prevalence of adequate TPI was associated with the prevalence of an adequate colostrum volume fed at first meal and the prevalence of an adequate time to first feeding. In summary, management practices varied greatly between farms and influenced the prevalence of adequate TPI.     

Rapid assessment of bovine colostrum quality: How reliable are transmission infrared spectroscopy and digital and optical refractometers?

The objectives of this study were to evaluate the performance of the transmission infrared (IR) spectroscopic method and digital and optical Brix refractometers for measurement of colostral IgG concentration and assessment of colostrum quality of dairy cows. Colostrum samples (n = 258) were collected from Holstein cows on 30 commercial dairy farms in Nova Scotia and Newfoundland, Canada. Colostral IgG concentrations of 255 samples were measured by the reference radial immunodiffusion (RID) assay and IR spectroscopy. The Brix scores were determined on 240 of these samples using both the digital and optical Brix refractometers. Approximately half (48%) of the colostrum samples had RID IgG concentrations <50 g/L, which was the cut-point for poor quality. The correlation between RID and IR IgG concentrations was 0.88. The correlations between RID IgG concentration and Brix scores, as determined by the digital and optical refractometers, were 0.72 and 0.71, respectively. The optimal cutoff levels for distinguishing good- and poor-quality colostrum using IR spectroscopy, and digital and optical Brix refractometers were at 35 g/L and 23% Brix, respectively. The IR spectroscopy showed higher sensitivity (90%) and specificity (86%) than the digital (74 and 80%, respectively) and optical (73 and 80%, respectively) Brix refractometers for assessment of colostrum quality, as compared with RID. In conclusion, the transmission-IR spectroscopy is a rapid and accurate method for assessing colostrum quality, but is a laboratory-based method, whereas Brix refractometers were less accurate but could be used on-farm.     

A calf-level study on colostrum management practices associated with adequate transfer of passive immunity in Québec dairy herds

The objective of this study was to identify the calf-level colostrum management practices associated with an adequate transfer of passive immunity (TPI; defined as serum Brix refractance ≥8.4% in the first week of life) in small-sized herds. A total of 818 calves from 61 commercial Holstein dairy farms were included in this observational cross-sectional study. For each calf, sex, colostrum delivery method, colostrum volume fed at first meal, and time to first feeding (delay between birth and first colostrum meal) were noted. Blood and colostrum samples were collected to estimate the serum and colostrum quality using Brix refractometry. To quantify the level of bacterial contamination in colostrum samples, total bacteria count and total coliform count (TCC) were measured using the Petrifilm (3M, St. Paul, MN) culture system. In this study, 68% of calves had an adequate TPI (≥8.4%). For data distribution, the 25th, 50th, and 75th percentiles were 1.3, 2.8, and 3.3 L for the colostrum volume fed at the first meal; 20.9, 23.5, and 26.5% Brix; and 1.1, 3.1, and 6.5 h for the time to first feeding of colostrum, respectively. The odds of adequate TPI were 2.6 times higher in calves receiving ≥2.5 L colostrum at their first meal, 2.9 times higher in calves receiving colostrum with ≥24.5% Brix, and 1.6 times higher in calves receiving colostrum within 3 h after birth, than in calves not meeting these criteria. In the present study, median bacterial contamination distribution (interquartile range) in the first colostrum meal was 14,000 cfu/mL (3,000–83,000 cfu/mL) for total bacteria count, and 0 cfu/mL (0–1,000 cfu/mL) for TCC. Total bacteria count and TCC were not associated with the odds of adequate TPI in the final model. Overall, these results suggest that specific calf-level colostrum management practices are associated with adequate TPI in small- to medium-sized dairy herds.