A First Approach of Using Ultrasound as an Alternative for Blanching in Vacuum-Packaged Potato Strips

The effect of ultrasound (US) (40 kHz, 200 W, 3 min), blanching (85 °C, 3.5 min), and the combination of both methods was evaluated on the quality of vacuum-packaged potato strips stored at 3 ± 1 °C for up to 10 days. For this study, two cultivars of potatoes were assessed. For blanched Agata samples, the lightness (L*) decreased over 12 % (p < 0.05). Moreover, their hue increased up to 100, obtaining lesser yellow potato strips. In contrast, US did not affect the hue values. The losses of firmness of blanched potato strips were notable (35 % for Agata and 51 % for Agria), whereas US did not change this property (p < 0.05). Nevertheless, no significant differences were found in the total starch content at 10 days. Agata and Agria showed different metabolic behaviors of sucrose in the refrigerated storage. Therefore, Agria cultivar retained better color after frying. These results suggest that US had less impact on color and improve the firmness in vacuum-packaged potato strips with no added chemicals.     

Hydrostatic pressure effects on the structural properties of condensed whey protein/lactose systems

Hydrostatic pressure effects on whey protein/lactose mixtures were recorded with subsequent analysis of their structural, molecular and glass transition properties in comparison to thermal effects at atmospheric pressure. Experimental techniques used were small deformation dynamic oscillation in shear, modulated differential scanning calorimetry, Fourier transform infrared spectroscopy, and theoretical modelling of glass transition phenomena. Levels of solids ranged from 30 to 80% (w/w) in formulations with a protein/co-solute ratio of four-to-one. Addition of lactose protects the secondary conformation of the protein under application of high hydrostatic pressure. Nevertheless, pressurized protein systems are able to form three-dimensional structures due to the reduction in polymeric free volume and the development of an efficient friction coefficient amongst tightly packed particles. Systems can be seen as developing a “molten globular state”, where the structural knots of pressure-treated networks remain in the native conformation but achieve intermolecular cross-linking owing to frictional contact. Furthermore, pressure treated assemblies of condensed whey protein preparations could match the viscoelasticity of the thermally treated counterparts upon cooling below ambient temperatures. That allowed examination of the physical state and morphology of a condensed preparation at 80% solids by the combined framework of reduced variables and free volume theory thus affording derivation of glass transition temperatures for pressurized and atmospheric samples.     

The impact of NERICA adoption on productivity and poverty of the small-scale rice farmers in the Gambia

The study assessed the causal effects of NERICA adoption on rice yields and income, using country-wide data of 600 rice farmers in The Gambia. To control for differences in socio-demographic and environmental characteristics of adopters and non-adopters and enable a causal interpretation of NERICA adoption on the variables of interest, the study used the counterfactual outcome framework to control for such differences. The results, based on observed sample estimates, showed significant differences in rice yields and income between the NERICA adopters and non-adopters. Further, the results of the framework, based on the Local Average Treatment Effect (LATE) estimates, which allowed a causal interpretation, showed that NERICA adoption significantly increased average rice yields and annual income of small-scale rice farmers by 157 kg per hectare and $148, respectively.     

Quantitative Determination for the Major Volatile Organic Compounds of <Emphasis Type="Italic">Tuber melanosporum</Emphasis> Fermentation System by Distillation–Solid-Phase Extraction–Gas Chromatography

A method using distillation–solid-phase extraction coupled with gas chromatography and flame ionization detector was developed for assaying the major volatile organic compounds (VOCs) (i.e., 3-methyl-1-butanol, 2-methyl-1-butanol, and 2-phenylethanol) in the Tuber melanosporum fermentation system. Satisfied linearity, precision, accuracy, and recovery obtained in the method validation test indicate that the method was simple, accurate, and reproducible. Furthermore, the developed analytical method was used for the dynamic monitoring of the T. melanosporum fermentation process, and the highest amount of major VOCs was occurred on days 9 and 10. This method can be employed to monitor the VOCs in the fermentation process and thus to evaluate the VOC quality of the truffle fermentation system.     

Optimization and Validation of a UV–HPLC Method for Vitamin C Determination in Strawberries (<Emphasis Type="Italic">Fragaria ananassa</Emphasis> Duch.), Using Experimental Designs

Vitamin C or total ascorbic acid (TAA) in fruits can be assumed as ascorbic acid (AA) plus dehydroascorbic acid (DHA) content. The aim of this work was to optimize and validate, using experimental designs, a new high-performance liquid chromatographic method for vitamin C determination in strawberries. The mobile phase (MP) consisted of a 0.03 M sodium acetate/acetic acid buffer, 5% methanol. For optimization, a Box–Behnken design was used (three factors at three levels: (a) pH of MP, 3.8–5.8; (b) wavelength, 240–270 nm; and (c) flow rate, 0.5–1.2 ml min⁻¹). Responses were: AA and TAA areas, peak widths, and retention times. A global optimization was performed using the Derringer desirability function, and a value of 0.84 was reached for the combination of design factors: A = 5.8, B = 251 nm, and C = 1.15 ml min⁻¹. Method validation, using AA standard solutions, included: linearity study, limits of detection and quantification, and calibration and analytical sensitivity quantifications. Precision and accuracy were studied in strawberry extracts. The coefficients of variation (percent) were: AA, 1.5%; TAA, 1.8%, and DHA, 4.9%. Accuracy was evaluated with AA standard spiked in 30–150% range of the expected amount of analyte in real samples. The joint confidence elliptical region test and t test were employed for the study of the difference between recoveries (percent) and the ideal 100%. The robustness was analyzed using a fractional factorial design (3⁴⁻²), and an AA recovery study after slight changes in operative variables was performed. The results indicate that the optimized method was linear, sensible, precise, accurate, and robust.     

N-(carboxymethyl)lysine content of foods commonly consumed in a Western style diet

The potential adverse effects on health of diet-derived advanced glycation end-products (AGEs) is of current interest, due to their proposed involvement in the disease progression of diabetic and uraemic conditions. However, accurate information about levels of AGEs in foods is lacking. The objective of this investigation was to determine the level of one particular AGE, N^ε-(carboxymethyl)lysine (CML), a marker of AGE formation, in a wide range of foods commonly consumed in a Western style diet. Individual foods (n = 257) were mixed, lyophilised, ground, reduced, fat-extracted, hydrolysed, and underwent solid-phase extraction. Extracts were analysed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Cereal (2.6 mg/100 g food) and fruit and vegetable (0.13 mg/100 g food) categories had the highest and lowest mean level of CML, respectively, when expressed in mg/100 g food. These data can be used for estimating potential consumer intakes, and provide information that can be used to educated consumers on how to reduce their CML intake.     

The evaluation of a PCR-based method for identification of Salmonella enterica serotypes from environmental samples and various food matrices

The most commonly used method for serotyping Salmonella spp. is based on the Kaufmann–White scheme, and is composed of serological reactions using antibodies to LPS agglutinins. The multiplex PCR used in this investigation was established by Kim et al. to serotype the 30 most common clinical Salmonella serotypes, as determined by CDC. The PCR assay consists of two five-plex reactions and a single two-plex PCR reaction, based on six genetic loci from Salmonella enterica serotype Typhimurium and four loci from S. enterica serotype Typhi. In this investigation, we further evaluated the method for serotyping Salmonella spp. using a reference collection, environmental samples collected from a Mid-Atlantic region tomato farm study, four food matrices spiked with different Salmonella serotypes and a proficiency test. The PCR assay was first evaluated using DNA isolated from pure cultures of isolates obtained from various clinical and environmental samples, and then DNA isolated from broth cultures of food matrices of “Red round” and Roma tomatoes, Romaine lettuce, green onions and Serrano peppers spiked with serotypes Newport, Typhimurium, Javiana and Saintpaul, respectively. The results showed that the PCR assay correctly serotyped Salmonella spp. from the clinical, environmental, spiked food matrices, and proficiency test samples. These findings are significant because the PCR assay was successful in the identification of Salmonella in the spiked samples in a broth culture containing other non-salmonella organism. This method may be a useful resource for the food safety community.     

Varietal Differentiation of Grape Juice Based on the Analysis of Near- and Mid-infrared Spectral Data

The aim of this study was to evaluate the usefulness of visible (VIS), near-infrared reflectance (NIR) and mid-infrared (MIR) spectroscopy combined with pattern recognition methods as tools to differentiate grape juice samples from commercial Australian Chardonnay (n = 121) and Riesling (n = 91) varieties. Principal component analysis (PCA), partial least squares discriminant analysis and linear discriminant analysis (LDA) were applied to classified grape juice samples according to variety based on both NIR and MIR spectra using full cross-validation (leave-one-out) as a validation method. Overall, LDA models correctly classify 86% and 80% of the grape juice samples according to variety using MIR and VIS-NIR, respectively. The results from this study demonstrated that spectral differences exist between the juice samples from different varietal origins and confirmed that the infrared (IR) spectrum contains information able to discriminate among samples. Furthermore, analysis and interpretation of the eigenvectors from the PCA models developed verified that the IR spectrum of the grape juice has enough information to allow the prediction of the variety. These results also suggested that IR spectroscopy coupled with pattern recognition methods holds the necessary information for a successful classification of juice samples of different varieties.     

Use of Protein Hydrolysate from Yellow Stripe Trevally (<Emphasis Type="Italic">Selaroides leptolepis</Emphasis>) as Microbial Media

The objective of this study was to investigate the potential use of protein hydrolysate from yellow stripe trevally as a nitrogen source for the growth of different microorganisms. Protein hydrolysates from yellow stripe trevally with different degrees of hydrolysis (5, 15 and 25%) prepared using Alcalase (HA) or Flavourzyme (HF) were determined in comparison with commercial Bacto Peptone. For bacteria, Staphylococcus aureus and Escherichia coli, HF with 25% DH (HF₂₅) yielded the highest cell density and specific growth rate (μ _max) and the lowest generation time (t _d) (p?Saccharomyces cerevisiae and Candida albicans, Bacto Peptone yielded the higher growth rate than did HA and HF (p?μ _max and t _d were observed for fungus, Aspergillus oryzae (p?>?0.05). The pH of culture broth containing HF₂₅ decreased markedly during the first 8 hours of cultivation of S. aureus and E. coli (p?S. aureus (p?25 rendered the similar growth and colony size of S. aureus (p?>?0.05), compared with that containing Bacto Peptone. Scanning electron microscopic study revealed no differences in size and shape of microorganisms cultured in HF₂₅ and Bacto Peptone (p?>?0.05).     

Co-production of Lactic Acid and <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> Cells from Whey Permeate with Nutrient Supplements

Lactic acid and cell production from whey permeate by Lactobacillus rhamnosus with different nutrient supplements were investigated in this study. Yeast extract was identified as the most effective nutrient affecting lactic acid production. Increase in inoculum size from 0.05% to 1% (v/v) resulted in a substantial increase in lactic acid productivity from 0.66 to 0.83 g L⁻¹ h⁻¹ (P < 0.001). The optimal temperature for lactic acid production was 37 °C, while the highest cell production was obtained at 42 °C. When whey permeate and yeast extract concentrations were 6.8% (w/v) and 3 g L⁻¹, respectively, lactic acid productivity reached 0.85 g L⁻¹ h⁻¹ after 48-h cultivation, which is 3.40 times of those without nutrient supplements.