I. Lobos, C.J. Moscoso, and P. Pavez. 2019. Calibration models for the nutritional quality of fresh pastures by near-infrared reflectance spectroscopy. Cien. Inv. Agr. 46(3):234-242.High levels of animal performance and health depend on high-quality nutrition. Determining forage quality both reliably and quickly is essential for improving animal production. The present study describes the use of near infrared reflectance spectroscopy (NIRS) for the quantification of nutritional quality (dry matter (DM), water-soluble carbohydrates (WSC), crude protein (CP), in vitro dry matter digestibility (DMD), organic matter digestibility (OMD), neutral detergent fiber (NDF) and the WSC/CP ratio) in samples from fresh pastures in southern Chile (39° to 40° S). Calibration models were developed with wet chemistry and NIRS spectral data using partial least squares regression (PLSR). The coefficients of determination in the validation set ranged between 0.69 and 0.93, and the error of prediction varied from 0.064 to 2.89. The evaluation of the model confirmed the high predictive ability of NIRS for DM and CP and its low predictive ability for DMD, OMD, NDF and the WSC/CP ratio. It was not possible to obtain a model for WSC because it would have required an increased number of samples to improve the spectral variability and the R 2 value (> 80%).
The chemical composition and quality of honey depend on the floral and geographical origin, extraction techniques, and storage, resulting in a unique product for each area. Currently, consumers are not only concerned about the chemical composition, quality, and food safety of honey, but also about its origin. The objective of this study was to characterize honeys produced in Chile’s central-southern region from a mineral and botanical perspective, thus adding value through differentiation by origin. Two hundred honey samples were used and underwent analysis such as melissopalynological composition, nutritional composition, and color. Forty-seven melliferous floral species were identified, out of which 24 correspond to exotic species and 23 to native species. Fifty-six percent were classified as monofloral honeys, 2% as bifloral, and 42% as multifloral. Moisture mean values (17.88%), diastase activity (15.53 DN), hydroxymethylfurfural (2.58 mg/kg), protein (0.35%), and ash (0.25%) comply with the ranges established by both the national and the international legislation; standing out as honeys of great nutritional value, fresh, harvested under optimal maturity conditions, and absence fermentation. Regarding color, light amber was prevalent in most territories. The territory where honey was produced, denoted relevant differences in all the parameters studied.
One of the challenges of modern grassland systems is to minimize nitrogen (N) fertilization without negatively affecting the forage yield. Therefore, critical N dilution curves (Nc = ac W−b) have been developed in different species to improve N fertilization management. The aim of this study was to validate a critical N dilution curve for hybrid ryegrasses. Two field experiments were conducted in southern Chile. Treatments were the factorial combination of two hybrid ryegrasses (Shogun and Trojan cultivars) and seven N fertilization rates (0, 50, 100, 200, 350, 525 and 700 kg N/ha). Factors were arranged in a split‐plot design, where forage species were assigned to main plots and N rates to subplots that were randomized into four blocks. A wide range in forage yield and plant N concentration was observed (yield: 0.16 and 3.9 Mg DM/ha and N: 1.6% and 5.1%). The variations in these traits were principally explained by the N levels and harvest times. Relative yield responses of both cultivars were significantly (p < 0.001, R2 = 0.81–0.87) related to the nitrogen nutrition index (NNI) calculated with different critical N dilution curves. However, the NNI calculated with N dilution curves from annual ryegrass best described the relative yield response of hybrid ryegrass. Therefore, this validated critical N dilution curve (%Nc = 4.1W−0.38) will serve as a useful diagnosis tool for improving the N fertilization management of grazing systems for hybrid ryegrasses.
N. Loyola, P. Pavéz, and S. Lillo. 2011. Pectin extraction from cv. Pink Lady (Malus pumila) apples. Cien Inv. Agr. 38(3): 425-434. The present study extracted pectin from Pink Lady apples (Malus pumila), which present at physiological maturity an average 50% of redcolor coverage, to assess whether this variety is characterized by a high (HM) or low methoxyl value (LM). The raw materials were obtained from the Marengo farm, Los Niches, Curicó province, in the south-central region of Chile. Acid hydrolysis was used and the material was then subjected to sensory analysis, evaluating the organoleptic characteristics of pectin. The pectin was extracted with citric acid, which was tested under three pH conditions (2.5, 3.0 and 3.5, the latter corresponding to the natural pH of apples) for 60 and 90 min and subjected to a constant temperature of 90 ºC. The degree of esterification (DE) of the pectin was measured and then pectin was dehydrated to evaluate its sensory attributes, such as color, flavor, texture and acceptability (scale of 1-7). Treatment T 1 (pH 3.5 for 90 min) presented the best extraction conditions (4.47 g or 7.25%), but the T 0 treatment (pH 3.5 for 60 min) was the method that presented the best quality (68.27% DE) and classified the pectin as HM. The sensory evaluation results showed that the treatments gave variable attributes: the pectin samples from the T 0 and T 1 treatments presented the same degree of preference, 5.28 and 5.10, respectively, by 13 trained judges.
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