A novel real-time polymerase chain reaction method for the detection of macadamia nuts in food

A real-time PCR-based method for the detection of macadamia nuts (fruits of Macadamia integrifolia or M. tetraphylla or their hybrids) in food products is described. The method consists of DNA isolation by chaotropic solid phase extraction and subsequent PCR with macadamia-specific primers and a TaqMan fluorescent probe. The primers and the probe were targeted to the gene encoding for vicilin precursor. The method was positive for M. integrifolia and M. tetraphylla and negative for 16 other plant species used in food industry, including peanuts, walnuts, hazelnuts, almonds, pistachio nuts, cashew nuts, Brazil nuts, and chestnuts. The DNA-based detection limit of the method was 1.45 pg. Using a series of model samples with defined macadamia nut contents, a practical detection limit of 0.02% (w/w) macadamia nuts was determined. Practical applicability of the PCR method was tested by the analysis of 14 confectionery samples. For all of the samples, results conforming to the labeling were obtained. The presented PCR method is useful for relatively fast, highly selective, and moderately sensitive detection of macadamia nuts in food samples.     

A novel real-time polymerase chain reaction (PCR) method for the detection of walnuts in food

A real-time polymerase chain reaction (PCR)-based method for the detection of the walnut (Juglans regia) component in food is described here. The method consists of DNA isolation by chaotropic solid phase extraction and the subsequent PCR with walnut-specific primers and a TaqMan fluorescent probe. The primers and the probe are targeted to the jug r2, a major allergen gene of walnut. The method was positive for 8 varieties of walnut and negative for all other tested plant materials used in food industry, including pecan nuts. The intrinsic detection limit of the method was 0.24 ng walnut DNA. Using a series of model pastry samples with defined walnut contents, a practical detection limit of 0.01% walnut content was estimated. Practical applicability of the PCR method was tested by the analysis of 13 food samples (bakery and confectionery products), out of which two cakes were found to contain walnuts although they were not adequately labelled. The presented PCR method is useful for sensitive and selective detection of walnuts in food samples and can be performed in one working day.     

Relative quantification of walnuts and hazelnuts in bakery products using real-time polymerase chain reaction

Two versions of real-time polymerase chain reaction (PCR) for relative quantification of walnuts and hazelnuts in bakery products were developed. The first method is a duplex real-time PCR with 5′-nuclease (TaqMan) probes labelled with FAM and JOE for walnuts and hazelnuts, respectively. The second method uses two real-time PCR assays for walnuts and hazelnuts with TaqMan probes labelled with FAM, carried out in separate microtubes, with normalisation of the results achieved by adding wheat as an internal standard. The internal standard is quantified in a duplex format using the TaqMan probe labelled with JOE. Both methods produced linear calibration curves (r² = 0.9813 for the former method, r² = 0.9992 for the latter) in the range 10–90% (w/w) for walnut–hazelnut mixtures. Almost identical calibration curves were obtained also for walnut–hazelnut mixtures diluted with inert matrix (oat flakes; the inert matrix accounting for 80 and 96% (w/w), respectively). Practical applicability of the developed methods was demonstrated on bakery products from the market. The developed methods will be useful for food control laboratories to facilitate authentication of bakery products with nut filling.     

A novel real-time polymerase chain reaction method for the detection of pecan nuts in food

A real-time PCR-based method for the detection of the pecan (Carya illinoiensis) component in food is described. The method consists of DNA isolation by chaotropic solid phase extraction and the subsequent PCR with pecan-specific primers and a TaqMan fluorescent probe. The primers and the probe are targeted to the putative gene for allergenic vicilin-like seed storage protein of pecan. The method was positive for 10 pecan varieties and negative for all other tested plant materials used in food industry, including walnut. The intrinsic detection limit of the method was 1 pg pecan DNA which corresponds to 1.2 haploid genome copies. Using a series of model pastry samples with defined pecan contents, a practical detection limit of 0.01% (w/w) pecan was estimated. Practical applicability of the PCR method was tested by the analysis of 13 food samples; no discrepancies between the declared and detected pecan contents were found. The presented PCR method is useful for sensitive and selective detection of pecans in food samples and can be performed in one working day.     

One-step multiplex PCR method for the determination of pecan and Brazil nut allergens in food products

BACKGROUND: A one‐step polymerase chain reaction (PCR) method for the simultaneous detection of the major allergens of pecan and Brazil nuts was developed. Primer pairs for the amplification of partial sequences of genes encoding the allergens were designed and tested for their specificity on a range of food components. RESULTS: The targeted amplicon size was 173 bp of Ber e 1 gene of Brazil nuts and 72 bp of vicilin‐like seed storage protein gene in pecan nuts. The primer pair detecting the noncoding region of the chloroplast DNA was used as the internal control of amplification. The intrinsic detection limit of the PCR method was 100 pg mL^?1 pecan or Brazil nuts DNA. The practical detection limit was 0.1% w/w (1 g kg^?1). The method was applied for the investigation of 63 samples with the declaration of pecans, Brazil nuts, other different nut species or nuts generally. In 15 food samples pecans and Brazil nuts allergens were identified in the conformity with the food declaration. CONCLUSION: The presented multiplex PCR method is specific enough and can be used as a fast approach for the detection of major allergens of pecan or Brazil nuts in food. Copyright © 2011 Society of Chemical Industry     

A novel real-time polymerase chain reaction method for the qualitative detection of pistachio in food

In order to provide an appropriate method for the detection of pistachio (Pistacia vera) in food products, a novel real-time PCR was developed. The pistachio-specific primers and the TaqMan fluorogenic probe were designed to target the internal transcribed spacer between 18S ribosomal RNA and 5.8S ribosomal RNA genes. Using dilutions of the pistachio DNA, the intrinsic detection limit of the method was determined to be 0.012 pg. At specificity testing, the method was positive for 11 pistachio varieties and negative for 26 plant and animal species used in food industry. A detection limit of 0.0004% (w/w) was determined for pistachio nuts in model pastry. Practical applicability of the elaborated method was tested by the analysis of 44 food samples, out of which 7 food products were identified as containing undeclared pistachio. The developed real-time PCR may be utilized for sensitive and selective detection of pistachio in food products.     

维珍果 品质创造效益

<正>"维珍果",富含维生素的珍(榛)果,是土耳其榛子在中国的注册商标名称。土耳其维珍果(中国)推广集团是由土耳其榛子推广集团为在中国开展榛子推广活动而与剑平国际集团合作成立的,旨在全国范围内推广土耳其榛子的机构。该机构成立于2001年,并于2003年在位于北京怀柔的雁栖工业开发区建立了土耳其维珍果示范中心,同时依托此示范中心成立了北京芬帝食品有限公司。     

维珍果在食品加工业的应用

<正>榛子,泛指桦木科榛属多种灌木或小乔木所结的坚果。由于其果仁味美可食、营养丰富,又有独特的风味,被视为干果中的佳品。"维珍果"--富含维生素的珍(榛)果,是土耳其榛子在中国的注册商标名称。 世界上共有20余种榛树,分布于北半球的寒温带至亚热带。土耳其是世界上第一个从事榛子生产和贸易的国家。     

走俏世界的土耳其维珍果

<正>榛子,是生长在许多国家的普通坚果,然而在土耳其人的精心培育下,却成了全球瞩目的维珍果,这其中自有奥妙。实用价值和营养价值     

Quantification of Hazelnut Content in Fillings of Cakes and Wafers Using Real-Time Polymerase Chain Reaction

A method for quantification of hazelnuts in fillings of cakes and wafers, using macadamia nuts as an internal standard material, was developed and evaluated. The method was based on quantitative adaptation of the previously developed real-time PCR for identification of hazelnuts. Calibration lines were constructed for two types of fillings, using series of model mixtures. The model mixtures for calibration of cake fillings consisted of hazelnuts and walnuts; the model mixtures for calibration of wafer fillings (pastes) consisted of hazelnuts and peanuts. Linear calibration lines were obtained for both types of matrix, and practical applicability of the developed method was demonstrated on food products from the market. The developed method may be useful for food control laboratories to facilitate analysis of food products with hazelnut filling.     

MALDI-based identification of stable hazelnut protein derived tryptic marker peptides

Food allergy is an important health problem especially in industrialised countries. Tree nuts, among which are hazelnuts (Corylus avellana), are typically causing serious and life-threatening symptoms in sensitive subjects. Hazelnut is used as a food ingredient in pastry, confectionary products, ice cream and meat products, therefore undeclared hazelnut can be often present as a cross-contaminant representing a threat for allergic consumers. Mass spectrometric techniques are used for the detection of food allergens in processed foods, but limited information regarding stable tryptic peptide markers for hazelnut is available. The aim of this study was to detect stable peptide markers from modified hazelnut protein through the Maillard reaction and oxidation in a buffered solution. Peptides ³⁹⁵Gly-Arg⁴⁰³ from Cor a 11 and ²⁰⁹Gln-Arg²¹⁷, ³⁵¹Ile-Arg³⁶³, ⁴⁶⁴Ala-Arg⁴⁷⁸ and ⁴⁰¹Val-Arg⁴¹⁷ from Cor a 9 hazelnut allergens proved to be the most stable and could be detected and confirmed with high scores in most of the modified samples. The identified peptides can be further used as analytical targets for the development of more robust quantitative methods for hazelnut detection in processed foods.     

让您信赖的坚果之王土耳其维珍果

<正>北京芬帝食品有限公司主要从事维珍果(土耳其榛子)的生产、加工和销售。榛子的进口和加工处理量已经由2003年全年15吨增加到2004年的90多吨,增加了500%;产品的品种也由过去整粒榛子仁和调味榛子仁的销售,增加到各种规格的榛子碎、榛子粉、榛子酱以及各种口味的系列维珍果产品开发上市顾客的满意率达到100%,这是公司一个可喜的开端,也是维珍果值得信赖的最好的表现。公司合理的人才和技术构架、先进的加工设备、完善的质量控制体系、     

Polymerase chain reaction (PCR) for the detection of celery (<Emphasis Type="Italic">Apium graveolens</Emphasis>) in food

A method based upon polymerase chain reaction (PCR) for the detection of celery (Apium graveolens) in food was developed. The method involves DNA isolation by chaotropic or non-chaotropic solid-phase extraction and PCR with primers oriented to the sequence of the nuclear gene encoding mannitol dehydrogenase. The PCR method was shown to be specific for celery, producing a 279 bp fragment with four celery varieties and negative results with other species commonly present together with celery in food products (16 samples). The detection limit of PCR was 490–1530 pg DNA, which corresponds to 10² genome copies. When evaluated with model samples of celery in meat pâtés, a detection limit of 0.1% (w/w) was determined. When used to analyse food products from the market (dried vegetable seasonings, dehydrated bouillons), all four products declared to contain celery were correctly identified as positive and all three products in which celery was not declared were identified as negative.     

Simultaneous detection of DNA from 10 food allergens by ligation-dependent probe amplification

The simultaneous detection of DNA from different allergenic food ingredients by a ligation-dependent probe amplification (LPA) system is described. The approach allows detection of several targets in a one-tube assay. Synthetic oligonucleotides were designed to detect DNA from peanuts, cashews, pecans, pistachios, hazelnuts, sesame seeds, macadamia nuts, almonds, walnuts and brazil nuts. The specificity of the system was tested with DNA from more than 50 plant and animal species. The sensitivity of the method was suitable to detect allergenic ingredients in the low mg kg^?1 range. The limit of detection (LOD) for single allergens in different food matrices was 5 mg kg^?1. The novel analytical strategy represents a useful tool for the surveillance of established legislation on food allergens within the European Union.     

Advances in cultivar choice,hazelnut orchard management,and nut storage to enhance product quality and safety: an overview

European hazelnut (Corylus avellana L.) is a major species of interest for nutritional use within the Betulaceae family and its nuts are widely used throughout the world in the chocolate, confectionery, and bakery industries. Recently its cultivation has been expanded in traditional producer countries and established in new places in the southern hemisphere, including Chile, South Africa, and Australia. Introducing hazelnut in new environments could reduce its productivity, lead the trees to experience eco‐physiological disorders, and expose the crop to high pressure from common and new pests and diseases. Thus, new approaches in cultivar choice guidance, in the sustainable orchard management and even in nut storage and kernel quality evaluation are urgently required to improve the hazelnut production and processing chain. The main objective of this study was to systematize the published information regarding recent findings about the cultural operations that directly influence nut and kernel quality, support varietal choice for new plantations, and list the recent advances in nut storage and in quality and safety evaluation. © 2020 Society of Chemical Industry     

Detection of pea in food by real-time polymerase chain reaction (PCR)

A qualitative 5′-nuclease real-time PCR-based method for the detection of pea (Pisum sativum) in food is described. The method consists of DNA isolation by chaotropic solid phase extraction and the subsequent PCR with pea-specific primers and a TaqMan fluorescent probe. The primers and the probe are oriented to the chloroplast DNA intron located between trnL and trnF exons encoding for tRNA. The analytical parameters of the method were inclusivity 100%, exclusivity 100% and the detection limit of 0.11±0.07 ng of pea DNA corresponding to 12±7 diploid pea genome copies. Using a set of model meat patés with defined pea contents, a matrix-related detection limit of 0.05% was determined and a linear calibration line was constructed. The presented analytical method was useful for qualitative detection or semiquantitative determination of pea in food products. The method was relatively fast because the analysis could be performed in one working day.     

Polymerase chain reaction coupled with peptide nucleic acid high-performance liquid chromatography for the sensitive detection of traces of potentially allergenic hazelnut in foodstuffs

A new DNA extraction method suitable for a wide variety of complex food matrices has been devised and applied in combination with a new polymerase chain reaction (PCR) method for the sensitive detection of a specific DNA sequence univocally identifying the presence of potentially allergenic hazelnut (Corylus avellana). A 156 base pair amplicon corresponding to an internal region of the complementary DNA of the major hazelnut allergen (Cor a 1) was designed, and was found to be highly specific; the method was tested on both pure and complex food matrices and was found to be able to confirm the presence of hazelnut down to 5 pg of its DNA. The sequence of the amplicon was further confirmed by high-performance liquid chromatography (HPLC) analysis with a specific peptide nucleic acid (PNA) probe. A 15-mer PNA probe was expressly designed and synthesized to hybridize an internal sequence of the previously described amplicon. Given its reported sequence specificity and high hybridization efficiency, the PNA probe was used to develop an anion-exchange HPLC method allowing for a fast and reliable confirmation of the identity of the amplified products. The PCR–HPLC method was successfully tested on commercial samples, allowing for the detection of the presence of potentially hidden allergens even in products where the presence of hazelnut as an ingredient or possible contaminant was not reported.     

A survey of the bacteriological quality of preroasted peanut, almond, cashew, hazelnut, and brazil nut kernels received into three Australian nut-processing facilities over a period of 3 years

There is little information about bacteriological quality of preroasted kernels available in the public domain. An investigation of the bacteriological quality of preroasted peanut, almond, cashew, hazelnut, and Brazil nut kernels received into three Australian nut-processing facilities was performed over a period of 3 years. A total of 836 samples were analyzed for aerobic plate count, and 921 samples for Salmonella and Escherichia coli. The 921 samples included 653 peanut, 100 cashew, 60 almond, 60 Brazil nut, and 48 hazelnut kernels. There was no E. coli detected in any sample. Salmonella subsp. II (Fremantle) was detected in one raw almond sample. The aerobic plate count percentages of positive samples with counts above the detection level of the plating method used (100 CFU/g) for peanuts, almonds, cashews, hazelnuts, and Brazil nuts were 84, 78, 74, 50, and 45%, respectively. Of the samples containing more than this detection limit, the means were 4.5, 4.4, 3.1, 2.5, and 3.8 log CFU/g respectively. Although roasted kernel quality was not within the scope of this survey, raw microbial bioload would be expected to reduce on roasting. The bacteriological quality of preroasted peanut, almond, cashew, hazelnut, and Brazil nut kernels received into nut-processing facilities in Australia does not appear to suggest a public health concern.     

A novel and simple approach for assessing the freshness of hazelnuts

Visual inspection and sensory analysis are the only suitable ways to assess the quality of hazelnuts under routine conditions. To obtain a more objective parameter for the freshness, a fast and easy-to-use method was developed. It is based on the well-known test for the germination capacity of seeds where their vitality is determined by use of 2,3,5-triphenyltetrazolium chloride (TTC) which is reduced by flavo enzymes to 1,3,5-triphenylformazane, which appears red. For the determination, 100 hazelnut halves were embedded in TTC containing methyl cellulose gel on a glass plate and kept at 35 °C in the dark. After 6 h, the cut planes of viable nuts were stained red, the cut planes of rotten nuts were yellow or brown, and the colour of dead or mould-infected nuts remained unchanged. The colour pattern was examined either visually by counting the coloured halves or with computer support using image editing software. The ratio of the sum of coloured areas to the total area of the hazelnut cut planes gave a measure of the average degree of viability ("vitality index"). The analysis of several samples of hazelnuts of well-defined age and storage conditions confirmed the efficiency of the method.     

Effects of Water,Sodium Hypochlorite,Peroxyacetic Acid,and Acidified Sodium Chlorite on In‐Shell Hazelnuts Inoculated with Salmonella Enterica Serovar Panama

Recent foodborne disease outbreaks involving minimally processed tree nuts have generated a need for improved sanitation procedures. Chemical sprays and dips have shown promise for reducing pathogens on fresh produce, but little research has been conducted for in‐shell hazelnuts. This study analyzed the effectiveness of 3 chemical sanitizers for reducing Salmonella on in‐shell hazelnuts. Treatments of water, sodium hypochlorite (NaOCl; 25 and 50 ppm), peroxyacetic acid (PAA; 80 and 120 ppm), and acidified sodium chlorite (ASC; 450, 830, and 1013 ppm) were sprayed onto hazelnut samples inoculated with Salmonella enterica serovar Panama. Hazelnut samples were immersed in liquid cultures of S. Panama for 24 h, air‐dried, and then sprayed with water and chemical treatments. Inoculation achieved S. Panama populations of approximately 8.04 log CFU/hazelnut. Surviving S. panama populations were evaluated using a nonselective medium (tryptic soy agar), incubated 3 h, and then overlaid with selective media (xylose lysine deoxycholate agar). All of the chemical treatments significantly reduced S. Panama populations (P ≤ 0.0001). The most effective concentrations of ASC, PAA, and NaOCl treatments reduced populations by 2.65, 1.46, and 0.66 log units, respectively. ASC showed the greatest potential for use as a postharvest sanitation treatment.