Nut Paste Research Articles

A Novel Real-Time Polymerase Chain Reaction Method for the Detection of Brazil Nuts in Food

A qualitative real-time PCR-based method for the detection of the Brazil nut (Bertholletia excelsa) component in food is described. The method consists of DNA isolation by chaotropic SPE and the subsequent PCR with Brazil nut-specific primers and a TaqMan fluorescent probe. The primers and the probe are targeted to the gene encoding for the 11s globulin of the Brazil nut. The method was positive for eight Brazil nut samples from the market and negative for all other tested plant and meat materials used in the food industry (36 samples). The intrinsic LOD of the method was 10 pg Brazil nut DNA. Using a series of model nut paste mixtures with defined Brazil nut contents, a practical detection limit of 0.1% (w/w) Brazil nut was estimated. Practical applicability of the entire method was tested by qualitative analysis of nine food samples; no discrepancies between the declared and detected Brazil nut contents were found. The presented PCR-based method is useful for sensitive and selective detection of Brazil nut in food samples.

Effect of Nut Paste Enrichment on Physical Characteristics and Consumer Acceptability of Bread

Four kinds of nut paste (almond, hazelnut, peanut, walnut) in three different percentages (5, 10, and 15%) were added to bread formula to study the morphogeometric and textural characteristics, and the consumer acceptability of enriched breads. The change of texture along time was also studied. Control bread presented the lowest volume, water loss and height, and the highest firmness and chewiness. The enrichment with 15% of nut paste caused a decrease in loaf volume, weight loss, cohesiveness, and resilience but an increase in height, firmness, and chewiness. Almond and walnut breads presented the lowest values in firmness and chewiness. The lowest cohesiveness and resilience corresponded to hazelnut bread. The increased firmness during storage was slower in enriched than in nonenriched breads. The adhesiveness, cohesiveness, and resilience decreases were more important in the first 2 days of storage. Breads added with 10 and 15% nut paste showed the highest intent for consumption, persistence, and texture values. Peanut-enriched bread was the least accepted bread. Only a third of the consumers were able to correctly identify the nuts added.

Effect of Nut Paste Enrichment on Wheat Dough Rheology and Bread Volume

The study was carried out to investigate the effect of nuts (almond, hazelnut, peanut, walnut) enrichment (5, 10 and 15%) on the rheological properties of dough using alveograph, consistograph and rheofermentometer measurements. The loaf volume (LV) of bread added nut paste was also determined. The increase in nut percentage increases the dough viscoelastic characteristics (tenacity, extensibility, and strength) and mixing time, but decreased the dough consistency and tolerance, and the CO2 production during fermentation. Loaf volume increased when 5 and 10% of nut paste are added. Dough added walnut paste presented the lowest tenacity, strength and water absorption values, but the highest values in dough development time, tolerance and stability. Dough added almond, hazelnut and peanut paste had a similar behavior during mixing and handling.

Water sorption isotherms of pistachio nut paste

SummaryMoisture sorption isotherms of pistachio nut paste were determined at 4 and 20 °C by using gravimetric method with saturated salt solutions. The moisture content of pistachio nut paste increased sharply at higher water activities as the temperature increased. Mathematical models of Brunauer et al., Anderson, Oswin, Halsey, Henderson, Kühn, Filonenko & Chuprin and Peleg were evaluated to determine the best fit for the experimental data. In this study, Peleg model was found to be adequate model for pistachio nut paste. By using Clausius–Clapeyron equation, the heat of sorption was determined. As moisture content increased the heat of sorption decreased.

Applicability of the generalised D’Arcy and Watt model to description of water sorption on pineapple and other foodstuffs

In this paper we adapt (developed by us recently) the Generalised D’Arcy and Watt (GDW) model to the description of water vapour sorption on foodstuffs. We show that this simple formula can successfully describe the set of sorption isotherms measured on pineapple (in the range of temperatures 20–50 °C) and reported in this journal by Hossain et al. [Hossain, M. D., Bala, B. K., Hossain, M. A., & Mondol, M. R. A. (2001). Sorption isotherms and heat of sorption of pineapple. Journal of Food Engineering, 48, 103–107]. Presented model also describes the isosteric enthalpy of sorption reported by those authors. We also show the applicability of GDW model to description of water sorption data on other foodstuffs (macaroni, sardine and pistachio nut paste) and we prove the inconsistency of the modified BET equation. Having strong kinetic basis, our model makes it possible to suggest the mechanism of water adsorption on foodstuffs, and can be successfully applied by researchers who are looking for mathematical equations to describe the sorption isotherms of food materials and/or calculate some parameters characterising water sorption mechanism.

The effect of the different packaging and storage conditions on the quality of pistachio nut paste

Pistachio nut paste samples were produced by boiling the mixture of 51% sucrose, 16% pistachio, 8% glucose and 25% water till the final 75 brix was reached. The samples were stored at 4 and 20 °C within sealed glass jars and vacuumed polyprophylene (PP) and non-vacuumed polyprophylene (PP) pouches. The experimental nut samples in three packing types at two storage temperatures were analysed for peroxide values (meq kg −1), total acidity (%), free fatty acid (%), moisture content (%), pH, browning indice and TBA values. Pistachio nut pastes were analysed monthly during the storage period up to 210 days. The experiment was carried out according to randomized blocks design with three replications (3 packaging × 2 temperature × 3 replications). Chemical properties of pistachio nut paste samples that stored at 4 °C were better than those stored at 20 °C within all packaging types. Storage of pistachio nut pastes at 20 °C resulted in shorter terms of shelf life. Pistachio nut pastes stored at 4 °C in sealed glass jars were more acceptable with respect to the chemical properties measured as compared to the other packaging types.

The fitting of various models to water sorption isotherms of pistachio nut paste

Moisture sorption isotherms of pistachio nut paste were determined using the gravimetric static method of saturated salt solutions at 10, 20 and 30 °C. Isotherms were found to be of type III. The effect of temperature on equilibrium moisture content values was not significant ( P > 0·05). The sorption isotherms did not exhibit hysteresis over the whole a w range. At higher water activities the moisture content increased sharply as the temperature was increased, resulting in a crossing of the isotherm curves. Five models available in the literature, namely the BET, GAB, Halsey, Henderson, and the Iglesias and Chirife, were evaluated to determine the best fit for the experimental data. The BET model used for data in the lower a w range (≤0·43) was found to be adequate and the Halsey model superior for characterising the sorption behaviour of pistachio nut paste in the temperature and water activity range investigated. The usual procedures for calculating isosteric heats of sorption by the application of the Clausius-Clapeyron equation was examined. The isosteric heats of sorption increased with decreasing moisture content.