Influence of Various Cooking Methods on the Concentrations of Volatile N‐Nitrosamines and Biogenic Amines in Dry‐Cured Sausages

Abstract: N‐nitrosamines, biogenic amines, and residual nitrites are harmful substances and are often present in cured meats. The effects of different cooking methods (boiling, pan‐frying, deep‐frying, and microwave) were investigated on their contents in dry‐cured sausage. The various N‐nitrosamines were isolated by a steam distillation method and analyzed by gas chromatography mass spectrometry (GC‐MS). The biogenic amines were determined after extraction with perchloric acid as dansyl derivatives by high‐performance liquid chromatography (HPLC) method. The results showed that initial dry‐cured raw sausage contained 5.31 μg/kg of total N‐nitrosamines. Cooking by deep‐frying or pan‐frying resulted in products having the highest (P < 0.05) contents, compared with boiling or microwave treatments, which were not different from the raw. Although frying increased the content of N‐nitrosodimethylamine (NDMA), N‐nitrosodiethylamine (NDEA), and N‐nitrosopyrrolidine (NPYR), it decreased the contents of histamine and cadaverine. Boiling and microwave treatments decreased the total biogenic amines significantly (P < 0.05). Residual nitrite was significantly reduced by cooking treatments. The results suggest that boiling and microwave treatments were more suitable methods for cured meat. Practical Application: N‐nitrosamines and biogenic amines are considered potentially harmful substances to humans and often present in dry‐cured sausage. Different cooking methods may effect the content of these harmful substances. However, little information exists on the different cooking methods on dry‐cured meats.     

Gluten‐Free Precooked Rice‐Yellow Pea Pasta: Effect of Extrusion‐Cooking Conditions on Phenolic Acids Composition,Selected Properties and Microstructure

Rice/yellow pea flour blend (2/1 ratio) was used to produce gluten‐free precooked pasta using a single‐screw modified extrusion‐cooker TS‐45. The effect of moisture content (28%, 30%, and 32%) and screw speed (60, 80, and 100 rpm) on some quality parameters was assessed. The phenolic acids profile and selected pasta properties were tested, like pasting properties, water absorption capacity, cooking loss, texture characteristics, microstructure, and sensory overall acceptability. Results indicated that dough moisture content influenced all tested quality parameters of precooked pasta except firmness. Screw speed showed an effect only on some quality parameters. The extrusion‐cooking process at 30% of dough moisture with 80 rpm is appropriate to obtain rice‐yellow pea precooked pasta with high content of phenolics and adequate quality. These pasta products exhibited firm texture, low stickiness, and regular and compact interne structure confirmed by high score in sensory overall acceptability.     

Influence of Jet‐Cooking Temperature and Ionic Strength on Size and Structure of Cationic Potato Amylopectin Starch as Measured by Asymmetrical Flow Field‐Flow Fractionation Multi‐Angle Light Scattering

Asymmetrical flow field‐flow fractionation (AsFlFFF) in combination with multi‐angle light scattering (MALS) was applied to cationic potato amylopectin (CPAP) to investigate how molar mass, root‐mean‐square (r.m.s.) radius and shape was influenced by different conditions of jet‐cooking. The effect of different jet‐cooking temperatures in the range 110°C – 140°C was studied in an excess steam jet‐cooker. This equipment is used in the industry for dissolution of starch and starch derivatives before technical application. The effect of different ionic strengths conditions was examined in the range of 10–200 mM. The weight‐average molar mass decreased from about 34×10⁷ g/mol to 2.6×10⁷ g/mol when the jet‐cooking temperature was increased from 110°C to 140°C. Concurrently the root‐mean‐square radius decreased from ca 380 nm to 90 nm. The decrease in size was reflected by a decrease in viscosity with increasing temperature. The root‐mean‐square radius was reduced when increasing the ionic strength. This decrease in size was correlated with a decrease in viscosity. Conformation and Kratky plots showed that at low ionic strength (≤ 10 mM) CPAP behaved as a flexible chain with high degree of branching, close to hyperbranching. Increase of the ionic strength gave a more compact structure and changes in the internal structure were observed as well. Consequently, by using AsFlFFF – MALS the effect of technical processing on the molar mass, molecular radius, conformational structure, and shape could be determined in a size region where standard methodology commonly fails.     

Effects of Different End‐Point Cooking Temperatures on the Efficiency of Encapsulated Phosphates on Lipid Oxidation Inhibition in Ground Meat

Effects of 0.5% encapsulated (e) phosphates (sodium tripolyphosphate, STP; sodium hexametaphosphate, HMP; sodium pyrophosphate, SPP) on lipid oxidation during storage (0, 1, and 7 d) of ground meat (chicken, beef) after being cooked to 3 end‐point cooking temperatures (EPCT; 71, 74, and 77 °C) were evaluated. The use of STP or eSTP resulted in lower (P < 0.05) cooking loss (CL) compared to encapsulated or unencapsulated forms of HMP and SPP. Increasing EPCT led to a significant increase in CL (P < 0.05). Both STP and eSTP increased pH, whereas SPP and eSPP decreased pH (P < 0.05). The higher orthophosphate (OP) was obtained with STP or SPP compared to their encapsulated counterparts (P < 0.05). The lowest OP was determined in samples with HMP or eHMP (P < 0.05). A 77 °C EPCT resulted in lower OP in chicken compared to 74 and 71 °C (P < 0.05), dissimilar to beef, where EPCT did not affect OP. In encapsulated or unencapsulated form, using STP and SPP enhanced reduction in TBARS and lipid hydroperoxides (LPO) compared with HMP (P < 0.05). Regardless of the phosphate type, more effective lipid oxidation inhibition was achieved by the use of encapsulated forms (P < 0.05). Increasing EPCT resulted in lower TBARS in beef and higher LPO values in both beef and chicken samples (P < 0.05). Findings suggest that encapsulated phosphates can be a strategy to inhibit lipid oxidation for meat industry and the efficiency of encapsulated phosphates on lipid oxidation inhibition can be enhanced by lowering EPCT.     

Content of anthocyanins and glycoalkaloids in blue‐fleshed potatoes and changes in the content of α‐solanine and α‐chaconine during manufacture of fried and dried products

In the last ten or so years, potatoes with purple or blue‐flesh and derivative products, for example chips, have appeared on the European markets. The interest in this raw material and these products is increasing among both producers and consumers searching for novel and attractive choices. The anthocyanin content of the analysed potato varieties differed; a higher content of these pigments was determined in Blaue Elise var. potatoes. In blue‐flesh varieties, the prevailing anthocyanins were acylated glycosides: petunidin and malvidin. The production process of French fries, chips and puree caused a decrease in the content of glycoalkaloids in semi‐products and finished products, compared to the raw material. The greatest losses of α‐chaconine and α‐solanine were observed after tuber peeling (ca. 70%) and after frying (ca. 90%). French fries contained 3%, chips 16% and puree 17% of the initial amount of total glycoalkaloids. The losses of α‐chaconine and α‐solanine in the analysed semi‐products and finished products were at the same level, regardless of the processing technology applied.     

Combined Application of Antibrowning,Heat Treatment and Modified‐Atmosphere Packaging to Extend the Shelf Life of Fresh‐Cut Lotus Root

This work aimed to determine the effects of different concentrations of antibrowning treatments (that is, distilled water [DW], 1% ascorbic acid [AA], 0.5% chamomile [CM], and 1% AA + 0.5% CM) and heat‐treatment (55 °C for 45 s) combined with packaging under 4 different modified‐atmosphere gas compositions (that is, air, vacuum, 100% CO₂, 50% CO₂/50% N₂) on the quality and microbiological characteristics of fresh‐cut lotus root. The quality characteristics (that is, color, weight loss, texture, pH, polyphenoloxidase activity, and total phenolic content) of the AA + CM‐dipped sample in 100% CO₂ packaging were maintained significantly better than those of the other samples (P < 0.05). The microbiological counts observed in the DW‐dipped sample during storage were higher than those of the AA, CM, and AA + CM samples, and heat‐treatment retarded the microbiological deterioration of fresh‐cut lotus root. Therefore, the results revealed that dipping in an antibrowning treatment (AA + CM), and 100% CO₂ MAP with heat treatment effectively extend the shelf life of fresh‐cut lotus root to 21 d at 5 °C.     

Dielectric determination of bio‐ and free‐calcium in commercial alkaline‐cooked ground corn

Using dielectric measurements, it was possible to determine the concentration of bio‐ and free‐calcium in a corn dough prepared mixing commercial powder of alkaline‐cooked ground‐corn kernel (maize), Zea mays, with different concentrations of Ca(OH)₂ and the same amount of water. This allows determining the conditions to obtain dough with high bio‐calcium content and consequently high nutritional value. The samples were placed in the interior of a small parallel‐plate capacitor. The capacitance and the cell current profiles were obtained with the corresponding relaxation times as a function of the Ca concentration. With this information, it was possible to determine the threshold concentration at which the Ca ions are not longer linked chemically to the cornstarch molecules and move freely in the interior of the dough. A model based on the ionic conductivity was developed to explain the dependence of the relaxation times with the Ca concentration.     

Functional characterization of steam jet‐cooked buckwheat flour as a fat replacer in cake‐baking

BACKGROUND: With rising consumer awareness of obesity, the food industry has a market‐driven impetus to develop low‐fat or fat‐free foods with acceptable taste and texture. Fancy buckwheat flour was thus subjected to steam jet‐cooking and the performance of the resulting product in cake‐baking was evaluated as a fat replacer. RESULTS: Steam jet‐cooking caused structural breakdown and starch gelatinization of buckwheat flour, thus increasing its water hydration properties. In the pasting measurements, steam jet‐cooked buckwheat flour exhibited high initial viscosity, while no peak viscosity was observed. Also, the suspensions of steam jet‐cooked buckwheat flour exhibited shear‐thinning behaviors, which were well characterized by the power law model. When shortening in cakes was replaced with steam jet‐cooked buckwheat gels, the specific gravity of cake batters significantly increased, consequently affecting cake volume after baking. However, shortening replacement with steam jet‐cooked buckwheat up to 20% by weight appeared to be effective in producing cakes as soft as the control without volume loss. CONCLUSION: When buckwheat flour was thermomechanically modified by steam jet‐cooking, it was successfully incorporated into cake formulations for shortening up to 20% by weight, producing low‐fat cakes with comparable volume and textural properties to the control. Copyright © 2010 Society of Chemical Industry     

Efficacy of Combined Sous Vide‐Microwave Cooking for Foodborne Pathogen Inactivation in Ready‐to‐Eat Chicory Stems

There is a variety of different food processing methods, which can be used to prepare ready‐to‐eat foods. However, the need to preserve the freshness and nutritional qualities leads to the application of mild technologies which may be insufficient to inactivate microbial pathogens. In this work, fresh chicory stems were packed under a vacuum in films, which were transparent to microwaves. These were then exposed to microwaves for different periods of time. The application of sous vide microwave cooking (SV‐MW, 900 W, 2450 MHz), controlled naturally occurring mesophilic aerobic bacteria, yeasts and molds for up to 30 d when vacuum‐packed vegetables were stored at 4 °C. In addition, the process lethality of the SV‐MW 90 s cooking was experimentally validated. This treatment led to 6.07 ± 0.7 and 4.92 ± 0.65 log cfu/g reduction of Escherichia coli and Listeria monocytogenes inoculated over the chicory stems (100 g), respectively. With an initial load of 9 log cfu/g for both pathogens, less than 10 cfu/g of surviving cells were found after 90 s cooking. This shows that short‐time microwave cooking can be used to effectively pasteurize vacuum‐packed chicory stems, achieving >5 log cfu/g reduction of E. coli and L. monocytogenes.     

Application of an In‐line Viscometer to Determine the Shear Stress of Plasticised Wheat Starch

An in‐line viscometer was designed and constructed to enable determination of the shear stress of plasticised wheat starch during extrusion cooking. The viscometer was installed between the end of the barrel section and the extruder die plate so that the shear stress could be determined for the plasticised material, irrespective of the geometrical shape into which it was subsequently moulded by the extruder die. The extrusion conditions were described in terms of the process parameters, i. e. water content, barrel temperature, screw speed and screw configuration; and of the system parameters, which were the specific mechanical energy input (SME), product temperature (PT) and mean residence time (MRT). The parameters were measured and the results evaluated using statistical methods. Regression equations were used to describe functional relationships between the shear stress and the extrusion conditions on the one hand, and between the shear stress and the product characteristics of the extrudates on the other. The shear stress of plasticised wheat starch determined in‐line can be used to predict the morphological structure (volumetric expansion) and the functional properties (cold paste viscosity and cold water solubility) of extruded, directly expanded starch with a high degree of accuracy. The measurement technique used and the results of the extrusion tests undertaken for this project will therefore enable the shear stress of plasticised material in an extruder to be used as the principle parameter for controlling extruders on‐line.     

Reduction of acrylamide formation in French fries by microwave pre‐cooking of potato strips

In this study, the effect of microwave pre‐cooking of potato strips on the resultant acrylamide levels in French fries was investigated. Control and microwaved (10, 20, and 30 s at 850 W) samples were fried at 150, 170 and 190 °C for predetermined times. Surface and core temperatures of potato strips were acquired during frying, and acrylamide content in the surface and the core regions were determined separately. The results showed that microwave application prior to frying resulted in a marked reduction of acrylamide level in the surface region, whereas a slight increase was noted for the core region. When the potato strips were subjected to frying after a microwave pre‐cooking step, acrylamide content in the whole potato strip was reduced by 36%, 41%, and 60% for frying at 150, 170, and 190 °C, respectively, in comparison to the control. Copyright © 2006 Society of Chemical Industry     

Evaluation of a Modified pH‐Shift Process to Reduce 2‐Methylisoborneol and Geosmin in Spiked Catfish and Produce a Consumer Acceptable Fried Catfish Nugget‐Like Product

Abstract: Muddy and/or musty off‐flavors in farmed‐raised catfish occur as a result of the absorption of geosmin (GEO) and 2‐methylisoborneol (MIB), compounds produced by algae. Previous research suggests the acid pH‐shift method may be able to reduce off‐flavors to produce a consumer acceptable product. The objective of this research was to evaluate application of the acid pH‐shift method using a shaker sieve for protein recovery and to evaluate consumer acceptability of a resultant batter‐coated fried nugget‐like catfish product. Farm‐raised catfish were either allowed to depurate (control) or treated with 1 ppb GEO or MIB. Fillets from each replicate were collected and ground and treated by the acid pH‐shift process. Samples from all treatments and replicates were evaluated for residual GEO and MIB. In addition, batter‐coated fried catfish samples were prepared for a consumer sensory evaluation. Results demonstrated that the pH‐shift process decreased moisture, ash, and collagen content of catfish fillet tissue (P < 0.05). Flavor of control samples was preferred (P < 0.05). Texture of catfish samples treated by the pH‐shift process was preferred (P < 0.05). Results demonstrate the pH‐shift process can be utilized to reduce off‐flavors and increase the acceptability of a processed catfish product. Practical Application: Use of a sieve as an economic alternative for the pH‐shift process was evaluated for removing off‐flavors from catfish. Difficulties were encountered with regard to protein recovery using the sieve and suggestions are made to, perhaps, make the process more applicable for a sieve‐based recovery step. The process as described reduced off‐flavors, but only 2‐fold suggesting the process would work best on catfish near or just over off‐flavor thresholds. Results also indicated the pH‐shift process could be used to improve texture of a fried catfish product designed to be similar to chicken nuggets.     

The use of selected hydrocolloids to enhance cooking quality and hardness of zero‐salt noodles

The effects of table salt (TS) and hydrocolloids on water‐holding capacity, optimum cooking time, cooking qualities, pH and textural properties of noodles were investigated. TS, xanthan gum (XG), carrageenan (CRG), Arabic gum (AG) and locust bean gum (LBG) were added at 0.5%, 1.0%, 1.5% and 2.0% of flour weight. XG, CRG and LBG contributed to significantly (P < 0.05) higher water‐holding capacity of dough and firmer texture, but significantly (P < 0.05) lower cooking loss than zero‐salt noodles (ZSNs) and white‐salted noodles (WSNs). Hydrocolloids contributed in shorter optimum cooking time than ZSNs. Springiness of noodles was not significantly (P > 0.05) affected by increment of TS and hydrocolloids. TS1.5, ZSN‐XG1.5, ZSN‐XG2.0 and ZSN‐CRG1.5 had significantly (P < 0.05) higher cooking yield than ZSNs. The increment of TS and hydrocolloids had significantly (P < 0.05) increased the pH values of noodles. ZSN‐XG2.0, ZSN‐CRG1.5 and ZSN‐LBG1.5 may be useful to enhance ZSNs due to the better noodles qualities than ZSNs.     

Effectiveness of chitosan‐based coating in improving shelf‐life of eggs

Despite eggs having a natural packaging—shell—they are perishable and can lose their quality during storage. Chitosan‐based coatings were applied to shell eggs to examine potential effects on egg quality properties (weight loss, Haugh unit, yolk index) during 4 weeks of storage. Mineral amounts in yolks were also evaluated after 4 weeks of storage. Three chitosan‐based coatings produced with organic acids (acetic‐(C‐AA), lactic‐(C‐LA), and propionic (C‐PA)) were evaluated on shelf‐life enhancements of fresh egg quality. All chitosan‐coated eggs showed greater interior quality than the non‐coated eggs. The coatings significantly maintained weight loss compared to the control specimen (4.96%). Lower weight loss (3.45% for C‐PA, 3.53% for C‐LA) was observed in the coated eggs. Eggshell chitosan coat containing lactic and propionic acids maintained higher Haugh unit and yolk index than eggs coated with acetic acid. Uncoated (UC) eggs changed from grade ‘A’ to ‘B’ after 1 week of storage. Chitosan‐based coating containing lactic and propionic acids maintained eggs in grade ‘A’ for 4 weeks. Haugh unit showed that C‐LA and C‐PA effectively maintained eggs at grade ‘A’ quality for at least 3 weeks more than control and 1 week more than C‐AA. Results also indicated that the chitosan coating maintained mineral amounts at nutritional values (especially calcium, iron and magnesium concentration) in yolks after 4 weeks storage. Copyright © 2006 Society of Chemical Industry     

The interaction of pulsed electric fields and texturizing ‐ antifreezing agents in quality retention of defrosted potato strips

The combination of pulsed electric fields (PEF) and texturizing and antifreeze agents on quality retention of defrosted potato strips were studied. Potato strips (10 mm thickness, 100 g) were placed in different solutions (1% w/v) of CaCl₂, glycerol, trehalose as well as NaCl and sucrose, treated with PEF (0.5 kV cm^?1, 100 pulses, 4 Hz). Then, all the samples were soaked in the same solutions for 10 min. After draining, samples were packed into polypropylene pouches and stored at ?18 °C for 12 h. Samples were thawed out at room temperature (20 °C) in 3 h. Untreated controls and PEF treated control samples were also frozen and thawed in similar conditions. To assess the potato strip quality, the thawed samples were analysed for moisture content, weight loss, firmness and colour attributes. The results indicate that PEF treatment by itself is not a suitable pre‐treatment method for frozen potato strips and should be assisted by CaCl₂ and trehalose treatment to prevent softening after defrosting. Firmness analyses determined that application of PEF alone results in 2.38 N. However, PEF in combination with CaCl₂ and trehalose result in 2.97 N and 2.99 N, respectively, which are both significantly firmer than the samples solely treated with PEF. CaCl₂ and trehalose were effective in not only maintaining the structural integrity of the cells, but also retaining colour attributes. The L* value was found to be higher (P < 0.05) in CaCl₂ and trehalose treated samples (58.95 and 57.21, respectively), as compared to PEF treated samples (53.97) denoting a darker colour. Application of CaCl₂ and trehalsoe in combination with PEF also resulted in significantly less weight loss after thawing.     

Use of Hydration, Germination, and α-Galactosidase Treatments to Reduce Oligosaccharides in Dry Beans

ABSTRACT: This investigation was done to determine an energetically feasible method to reduce bean oligosaccharides (stachyose and raffinose) for large-scale bean flour production. Michigan black, red, and navy beans (all Phaseolus vulgaris ) were treated by α-galactosidase, germination, or hydration to determine treatment effects on stachyose and raffinose levels. Oligosaccharides were extracted with 70% (w/w) ethanol, and α-galactosidase was added to catalyze hydrolysis of the oligosaccharides. Enzyme treatment was for 1 h at ambient temperature (23°C). For germination, whole beans were incubated in a germinating chamber (100% humidity, 26.7°C) for 48 h. In hydration, whole beans were soaked in excess water at ambient temperature (23°C) for 5 h. Enzyme treatment resulted in 51%± 3.0%, 30%± 1.9%, and 46%± 1.9% reduction in total raffinose and stachyose for black beans, red beans, and navy beans, respectively. Germination treatment resulted in 61%± 12%, 61%± 1.9%, and 70%± 2.8% reduction in total raffinose and stachyose for black beans, red beans, and navy beans, respectively. Hydrated black beans showed a loss of 33%± 9.6%, whereas hydrated red and navy beans showed no reduction of oligosaccharides. Although germination showed the greatest reduction in bean oligosaccharides, this method may not be as cost-effective commercially as the enzyme treatment because of the time required for germination.     

Evaluation of heat propagation through poultry in a reduced computational‐cost model of contact cooking

During thermal food preparation, it is essential for the product to reach safe temperature thresholds. Yet, excessive cooking is time‐consuming and decreases desirable qualities. In this work, we developed, and experimentally verified, a computationally minimum mathematical model to predict one‐dimensional temperature distribution through contact cooking of poultry. This model was based on discretising the heat equation with temperature and time varying thermophysical properties of the major constituents: water, proteins and lipids. The relative amounts of these constituents are available from the United States Department of Agriculture (USDA) for different poultry samples. Our results yielded an average modelling experimental temperature error of 3.15 °C. For contact cooking of a 1‐cm thick sample, the minimum time to reach the temperature threshold in a chicken breast was 368 s compared to 98.9 s when flipped at an optimised time. These techniques can be implemented into a microprocessor‐based thermal monitoring system to non‐invasively predict temperature distribution in processed meat and poultry.     

Effect of Pretreatments and Air‐Frying,a Novel Technology,on Acrylamide Generation in Fried Potatoes

This paper investigated the effect of air‐frying technology, in combination with a pretreatment based of soaking the samples in different chemical agent solutions (citric acid, glycine, calcium lactate, sodium chloride, or nicotinic acid [vitamin B3]), on the generation of acrylamide in fried potatoes. The influence of reducing sugars on the development of surface's color was also analyzed. The experiments were conducted at 180 °C by means of air‐frying and deep‐oil‐frying, as a reference technology. Based on the evolution of color crust with frying time, it could be concluded that the rate of Maillard reaction decreased as the initial reducing sugars content increased in the raw material, and was also lower for deep‐oil‐frying than for air‐frying regardless of pretreatments applied. Air‐frying reduced acrylamide content by about 90% compared with conventional deep‐oil‐frying without being necessary the application of a pretreatment. However, deep‐oil fried potatoes pretreated with solutions of nicotinic acid, citric acid, glycine at 1%, and NaCl at 2% presented much lower acrylamide levels (up to 80% to 90% reduction) than nonpretreated samples.     

Effectiveness of antioxidant‐impregnated film in retarding lipid oxidation

The effectiveness of an antioxidant‐impregnated film to retard autoxidation of a packaged model product containing linoleic acid, via an evaporation/sorption mechanism, was evaluated as a function of storage time and temperature. The rate of loss of antioxidant from the package film structure was described by a first‐order expression. The first‐order rate constants were dependent on the initial concentration of antioxidant in the film. The rate of loss of 3,5‐di‐tert‐butyl‐4‐hydroxytoluene (BHT) from the package film structure was found to be much higher than the rate of loss of α‐tocopherol at both storage conditions (23 and 45 °C, 50% relative humidity) studied. A freeze‐dried model food product system was developed as the source for the autoxidation of linoleic acid in storage stability studies. The storage stability of this model food system packaged with antioxidant‐impregnated film pouches was evaluated. Hexanal as an index of oxidation from the model product system was collected by a dynamic purge and trap system and quantified by a gas chromatography/mass spectrometry procedure. The BHT‐impregnated laminate pouch showed a notable effectiveness in retarding lipid oxidation of the model product at 45 °C as a function of storage time. The control (non‐antioxidant) and α‐tocopherol‐impregnated laminate pouch structures showed no effect on retarding lipid oxidation of the model product during storage at 45 °C. Copyright © 2004 Society of Chemical Industry