Effect of green tea extract and microwave pre-cooking on the formation of heterocyclic aromatic amines in fried chicken meat products

Heterocyclic aromatic amines (HAAs) are mutagenic compounds formed naturally in meats after thermal processing and are classified as a probable human carcinogen. Also, mutagenic potency of HAAs is about 100-fold stronger than that of aflatoxin and 2000-fold stronger than that of benzo[a]pyrene. The aims of the present study were to investigate HAA contents and to determine HAA existence in coated chicken drumsticks (CDs) and coated chicken wings (CWs) which are frequently consumed in fast food chains after purchasing from fast food restaurants, and the effects of green tea extract added into the cover material and microwave-precooking for the mitigation and the formation of HAAs in CD and CW samples produced using a laboratory model. HAA (IQx, IQ, MeIQx, MeIQ, 7,8-DiMeIQx, 4,8-DiMeIQx, PhIP, AαC, MeAαC) analysis was done by HPLC after solid-phase extraction. MeIQx is the dominant HAA in all CD and CW samples obtained from fast food restaurants, and its level was found to vary between 0.22–33.73 and 11.22–62.83 ng/g, respectively. PhIP was detected in 5 out of 20 samples from fast food restaurants with a maximum level of 3.15 ng/g, and IQx, 7,8-DiMeIQx, AαC, and MeIQ were also detected. MeIQx values of CW and CD samples produced with the laboratory model varied between not detected and 1.45 and not detected and 2.32 ng/g, respectively, while IQ, MeIQ, 7.8 DiMeIQx, 4,8-DiMeIQx, AαC, and MeAαC were not detected in any of the CW or CD samples produced using the laboratory model. HAA contents of CD and CW samples obtained from fast food restaurants were higher than those of samples produced using the laboratory model due to the possible effect of uncontrolled frying conditions in restaurants. In addition, it was determined that the addition of green tea extract (GTE) and microwave pre-cooking (MC) did not present any detectable effect on reducing the formation of HAAs in fried CDs and CWs produced using a laboratory model under controlled frying conditions.     

Influence of cooking conditions on cooking loss and tenderness of raw and marinated chicken breast meat

The influence of different cooking treatments on tenderness and cooking loss, as main quality characteristics of chicken breast meat, was investigated. Industrial skinless chicken breast meat samples were designated as raw and marinated and cooked in the oven by hot air and hot air-steam mixture at 130, 150 and 170 °C, for 4, 8 and 12 min. Cooking losses were evaluated by weight changes before and after cooking, and tenderness changes were determined on cooked samples by measuring shear force using instrumental texture analysis. Results showed that marination, followed by air-steam cooking is the best combination to obtain the most tender chicken breast slices. The time and temperature of cooking showed similar effects on cooking loss and tenderness: short cooking time (4 min) and temperatures of 130–150 °C resulted in lower cooking losses and best meat tenderness, in both not marinated and marinated meat. Statistically significant correlations between tenderness and cooking loss indicated that the cooking loss correlated better with cooking time than with cooking temperature. An opposite phenomenon was observed for meat tenderness.     

Acrylamide content and color development in fried potato strips

Acrylamide formation and changes in color of fried potato strips was investigated in relation to frying temperature and three treatments before frying. Potato strips (0.8 × 0.8 × 5 cm) of Bintje variety were fried at 150, 170 and 190 °C until reaching moisture contents of ∼40 g water/100 g (total basis). Prior to frying, potato strips were treated in one of the following ways: (i) immersed in distilled water for 0 min (control), 60 min and 120 min; (ii) blanched in hot water at six different time–temperature combinations (50 °C for 40 and 80 min; 70 °C for 10 and 45 min; 90 °C for 3 and 10 min); (iii) immersed in a citric acid solution of 10 g/L for an hour; (iv) immersed in a sodium pyrophosphate solution of 10 g/L for an hour. Acrylamide content and color was determined in the potato strips after frying. Immersed strips in water for 120 min showed a reduction of acrylamide formation of 33%, 21% and 27% at 150, 170 and 190 °C, respectively, when they were compared against the control. Potato strips blanched at 50 °C for 80 min had the lowest acrylamide content when compared against strips blanched at different conditions and fried at the same temperature (135, 327 and 564 μm acrylamide/kg for 150, 170 and 190 °C, respectively). Potato strip immersion in citric acid solution of 10 g/L reduced much more the acrylamide formation after frying than the strip immersion in sodium pyrophosphate solution of 10 g/L (53% vs. 17%, respectively, average values for the three temperatures tested). Acrylamide formation decreased dramatically as the frying temperature decreased from 190 to 150 °C for all the pre-treatments tested. Color represented by the parameters L* and a* showed high correlations (r² of 0.79 and 0.83, respectively) with French fry acrylamide content.     

Reduction of acrylamide by taurine in aqueous and potato chip model systems

Acrylamide in foods is mainly produced by Maillard reaction. Taurine can participate in the reaction, which has led us to investigate the possibility of reducing acrylamide formation by use of taurine. In an aqueous system, the lower the pH of the solution the greater the inhibition of acrylamide formation within a pH range of 5.0–8.0 was found, and the inhibition of acrylamide formation by taurine was dose-dependent. In a fried potato chip model, prior to frying at 170 °C for 3 min, the potato slices soaked in 0.l% to 2% taurine solution for 30 min showed significant reductions of acrylamide formation; however, these reductions were not dose-dependent. Also, the soaking treatments for 15–60 min significantly reduced acrylamide formation, but the inhibitory effects were not time-dependent. Thus, taurine, when used in a narrow range of reasonably low levels, is a candidate to inhibit acrylamide formation during frying process.     

Investigation of the formation of (E)-2-butenal in oils and foods during frying

The formation of (E)-2-butenal in oils subjected to temperatures applied in frying as well as in fried foods was evaluated. For this purpose, a sensitive and accurate stable isotope dilution essay was developed and validated using as an internal standard (E)-2-butenal d6 synthesized in the lab. Heating of corn oil, sunflower oil, extra virgin and refined olive oil, ω-3 frying oil and palm oil at 170 °C for a total of 8 h resulted in the formation of (E)-2-butenal at levels between 0.05 and 1 μg g^− 1 and the highest amounts were already formed after 2 h of heating. The highest (E)-2-butenal formation was observed in the oil containing ω-3 unsaturated fatty acids indicating that (E)-2-butenal content is mainly affected by the fatty acid composition. No significant amount of free (E)-2-butenal was detected in fried foods purchased from fast food shops with the exception of one chicken sample and a pork brochette. Further experiments including several foods did not indicate any increase of free (E)-2-butenal content due to frying. It can be suggested that fried foods may not be a significant dietary source of free (E)-2-butenal for humans. However, these results in combination with the available literature indicated that investigation of the contamination of the indoor environment where frying is taking place could be more relevant than the presence of free (E)-2-butenal in oils and foods.     

Effects of ultrasound pretreatments on the kinetics of moisture loss and oil uptake during deep fat frying of sweet potato (Ipomea batatas)

The possibility of ultrasound assisted pretreatments of sweet potato to lower the moisture content and oil uptake during deep fat frying and its effects on the mass transfer rate was investigated. Sweet potato samples prior to frying were immersed in distilled water with ultrasound (UD), osmotic dehydration without ultrasound (OD) and ultrasound assisted osmotic dehydration (UOD). Ultrasound probe having frequency of 28 kHz at 300 W maximum power and time of 30 min was used for the pretreatment. The control (without pretreatment) and the pretreated samples were fried using sunflower oil at temperature of 130, 150 and 170 °C for 2, 4, 6, 8 and 10 min. The first order kinetic model was used for the mass transfer rate for moisture loss and oil uptake. The lowest moisture content was found in fried samples pretreated in UOD and OD while the lowest oil uptake was obtained in fried samples pretreated in UD having 65.11 and 71.47% oil reduction at temperature of 150 and 170 °C, respectively, compared to the untreated sample. The k values of all pretreated samples were higher than that of the untreated at 150 and 170 °C. The highest activation energy for moisture loss was found in untreated samples while the lowest activation energy for oil uptake was found in samples pretreated in UOD. The results from this work proved that ultrasound is a good pretreatment that can be used to obtain a low moisture content and oil uptake during deep fat frying of sweet potato.Industrial relevanceUltrasound is a novel technology that is widely used in the food industries because of its numerous advantages over conventional methods. Its application in the frying of foods could also help in the reduction of oil uptake, thus making safe the consumption of fried foods. The information about frying kinetics could also help in the design and optimization of the process in the food industry.     

Effect of Boiling and Frying on the Total Carbohydrate,Vitamin C and Mineral Contents of Irish (Solanun tuberosum) and Sweet (Ipomea batatas) Potato Tubers

In a study aimed at ascertaining whether boiling or frying best conserves nutrients; since the two methods are commonly adapted in Nigeria, the effect of boiling and frying on total carbohydrate, vitamin C and mineral contents of Irish (Solanum tuberosum) and sweet (Ipomea batatas) potato tubers were investigated. The determination of total carbohydrate was carried out using the phenol-sulphuric acid method and the spectrophotometric method was used to determine vitamin C content at 520 nm. The minerals evaluated are iron, zinc, magnesium, sodium, calcium and copper. These were determined by the atomic absorption spectrophotometric method. There was no significant difference (p > 0.05) in the total carbohydrate content of the boiled and fried sweet and Irish potatoes compared with their raw tubers. There was significant difference (p < 0.05) in the vitamin C content of the boiled and fried potato tubers. Boiling and frying of Irish potato resulted in a loss of 37.34 mg/100 ml (63.90%) and 30.44 mg/100 ml (53.90%) vitamin C respectively. Boiled sweet potato lost 51.16 mg/100 ml (72.37%) and fried lost 43.05 mg/100 ml (60.90%) of vitamin C. The mineral compositions of the boiled and fried Irish and sweet potatoes were significantly different (p < 0.05) from their raw tubers. Boiling retained more iron and copper while frying retained more zinc, magnesium, sodium and calcium in both Irish and sweet potato tubers. Boiling retained more carbohydrate while frying retained more vitamin C and minerals.     

Influence of addition of green tea and green coffee extracts on the properties of fine yeast pastry fried products

This study investigated the influence of antioxidants of green tea aqueous extract (GTE) and green coffee aqueous extract (GCE) in concentrations of 0.25, 0.5 and 1 g·100 g^? 1 on the nutritional properties of fine yeast pastry fried products such as donuts. Yeast donuts were made according to the traditional processing technology. In fried donuts physical properties (water activity, pH, hardness and color with the use of instrumental methods) as well as sensory properties were established. Moreover, quality of fat extracted from donuts (composition of fatty acids and peroxide value), content of acrylamide, composition of polyphenols and antioxidant activity were analyzed. Obtained extracts of GTE and GCE contained 26 and 41% of polyphenols, respectively, and the degree of polyphenol degradation during production of donuts was less when the dilution in dough was greater. Both tests indicated that the highest antioxidant activity had donuts with the highest analyzed addition of extract, however depending on the applied test or GTE or GCE had better antioxidant properties. Fatty acid composition was the most beneficial when the addition of GTE and GCE was on a level of 0.25 and 0.5 g·100 g^? 1, respectively. In fried donuts relatively low amounts of acrylamide were obtained, amounting to 18–46 μg·kg^? 1. Only the lowest addition of GTE and the highest addition of GCE caused an increase of acrylamide content in donuts, while all other levels of added extracts caused a decrease in the content of formed acrylamide.     

Quality Evaluation of Edible Film-Coated Chicken Strips and Frying Oils

ABSTRACT: Methyl cellulose (MC) and hydroxypropylmethylcellulose (HPMC) edible film materials were applied to marinated whole chicken strips either prior to breading, after breading, or were incorporated in the breading. Subsequently, the influence of an edible film's location relative to the crust on fried food product quality and the quality of the frying oil were determined. Films applied to chicken strips prior to the breading had fried crusts with higher fat and lower moisture levels. Decreased degradation of frying oils was recorded when product coated with HPMC (food grade E4M) films had been fried compared to non-coated product. It is postulated that these edible films hindered the migration of moisture and acetic acid into the frying oil and this activity was responsible for reduced free fatty acid generation in those oils used to fry the coated products.     

Deterioration of olive,corn and soybean oils due to air,light, heat and deep-frying

To follow the relative rate of oxidative deterioration of edible oils, refined olive, corn and soybean oils were analyzed periodically for their peroxide value (PV), p-anisidine value (p-AV) and iodine value (IV) following exposure to air and air–light for 30 days. Changes in the above values of the oils were also examined and after being used for deep frying of French fries at 180 °C for varying periods of time i.e. 30, 60 and 90 min PV and p-AV values increased in the order, deep frying > air–light exposure > air exposure, while the values with respect to the oils increased as soybean > corn > olive. Decreases in IV followed the same pattern, i.e. deep frying > air–light > air and soybean > corn > olive. %Free fatty acid increased with increase in time of deep-frying. Deep-frying of French fries in corn oil was also carried out in presence of caffeic, ferulic, vanillic acid and crude tea extract as antioxidants. All antioxidants effectively reduced the oxidation rate in the oil as detected by decreases in PVs and p-AVs and relatively low reduction rates in IVs for all the frying times. The order of antioxidative activity was caffeic acid > vanillic acid > ferulic acid > tea extract. Variation in %FFA of corn oil due to variation in nature of fried food was also analyzed. %FFA of the oil used for deep frying of chicken drum sticks were higher than the values of the oil used for deep-frying of French fries.     

Protective role of vacuum vs. atmospheric frying on PUFA balance and lipid oxidation

The effect of vacuum frying processing on proximate composition, fatty acid profile, oxidative status and sensorial properties of fish patties, was evaluated as compared with conventional (atmospheric) frying.Vacuum frying procedure was carried out at 80 mmHg (water boiling point: 42 °C) and oil temperature (107 °C) determined to obtain an equivalent thermal driving force (Δ65 °C) of that of the atmospheric frying conditions used (165 °C). Frying times of 2, 4, 6, 8 and 10 min were investigated.Vacuum frying significantly prevented degradation of EPA (Eicosapentaenoic acid) and DHA (Docosahexaenoic acid), reducing the polyene index and maintaining a lower ω6/ω3 fatty acid ratio in samples, while no significant differences with conventional frying in total oil content were observed. The use of vacuum also reduced formation of peroxides and carbonyl derivatives. Tocopherol levels decreased in all samples regardless of the frying conditions used, although vacuum-fried samples maintained higher tocopherol levels after processing. These samples also showed higher lightness and lower a* and b* values, which can be associated to lower non-enzymatic browning levels.These results support the applicability of vacuum frying technology for fish patties, since it prevents colour changes, improves juiciness and reduces oxidation when compared to conventionally (atmospheric) fried counterparts.Industrial relevanceConsumers are increasingly aware of the link between food and health, maintaining a high demand for healthy products. In this regard, consumption of fatty fish, with healthy properties widely known, is lower than recommended by health authorities, especially in children. Novel processing technologies focused on increasing the appealing of products based on fatty fish can help in ameliorating this deficient consumption. Vacuum frying is a promising way of obtaining attractive products, due to some product modification after the deep-fat frying process, and yet retaining natural colour, juiciness and healthy properties to a high extent. Vacuum frying allows reducing ω3 fatty acids and tocopherol degradation, differentiating fish products so obtained, which can be launched into the market and benefit from this technology. Compared to conventional frying, the results are better nutritional and sensory properties in a final product.     

Heat transfer coefficients during deep fat frying of sweetpotato: Effects of product size and oil temperature

Heat transfer coefficient, h during deep fat frying of sweetpotato was determined from designed experiments. Samples of three different disc sizes were fried at four oil temperatures between 150 and 180 °C. Heat transfer coefficient estimation was based on heat energy balance between the oil and sample during frying. Maximum h was reached at the earlier stage of frying (80–120 s). The range of maximum h reached was 710–850 W/m² °C. h at latter period of frying (200–300 s) was 450–550 W/m² °C. h was found to vary directly with oil temperature but inversely with sample size (p <0.05).     

Application of statistical process control,sampling, and validation for producing Listeria monocytogenes-free chicken leg quarters processed in steam followed by impingement cooking

Chicken leg quarters (180–230 g) were processed for 4 min in steam at 99°C and then in an air impingement oven for 24 min at an oven temperature of 232°C, an air velocity of 2 m/s, and a humidity of 60%. The cooked chicken leg quarters were sampled to measure for the end-point internal temperatures. Sampling size in each subgroup for the internal temperature measurements was determined based on a normal distribution at a confidence level of 95%. The process mean, range, and standard deviation at 95% confidence level were 73.9°C, 1.8°C, and 0.9°C, respectively, for the internal temperatures of the cooked chicken leg quarters. The process lethality was validated for up to 7  log₁₀ cfu/g reductions of Listeria monocytogenes in the cooked chicken leg quarters and verified by an inoculation study in which the chicken leg quarters were injected with 0.1 ml of the culture per cm² of the product surface area to contain 7–8 log₁₀ cfu/g of L. monocytogenes. This paper provided an approach for process control, sampling, and validation to reduce pathogens in fully cooked poultry products.     

Heat transfer modeling of chicken cooking in hot water

To calculate the slowest heating point and optimum cooking time of whole chicken cooking in hot water, a 2-dimensional heat transfer model was developed to predict temperature profile and history of the chicken cooked in hot water at 85, 90 and 95 °C. Chickens were divided into 12 sections and the heat transfer model was applied to each cross section. These models were solved with an I-DEAS program. Specific heat and thermal conductivity were measured at temperatures ranging from 25 to 95 °C. The temperature of chicken did not significantly affect the thermal properties. The average values of specific heat of white and dark meats were 3.521 and 3.654 kJ/(kg K), respectively, and the average thermal conductivity values were 0.5093 and 0.4930 W/(m K), respectively. The model was validated against experimental results, and provided an average root mean square error of 2.8 °C. Temperature distributions showed that the slowest heating point was deep in the breast part of the second cross section (3.6 cm far from shoulder) at the symmetric line of the chicken, around 2.1–2.5 cm deep from breast skin. For food safety consideration, the recommended cooking times, for whole chickens in weight range of 2.3–3.2 kg with different initial temperatures (5–30 °C), were around 74–84, 64–74 and 57–67 min for cooking temperatures of 85, 90, and 95 °C, respectively.     

Milk enhances intestinal absorption of green tea catechins in in vitro digestion/Caco-2 cells model

The effect of milk on the absorption of polyphenols is still controversial so far. In order to determine the impact of milk addition on green tea catechins bioaccessibility and intestinal absorption an in vitro digestion/Caco-2 cell model was applied. Green tea extract (GTE) was solubilized in distilled water at 23 °C and 100 °C, combined with skimmed milk (GTE + 10% milk and GTE + 25% milk) and subjected to simulated gastric and intestinal digestion, followed by transepithelial absorption in Caco-2 cells monolayers. In the mixture with milk, gallated catechins: ECG and EGCG showed binding to milk proteins while EC and EGC seemed to have weaker affinity. Catechins were stable during gastric incubation and very sensitive to intestinal digestion. Bioaccessibility of green tea catechins brewed at 100 °C was higher than brewed at 23 °C. Catechins from digested GTE with 10% and 25% milk exhibited enhanced intestinal permeability in Caco-2 model in comparison to non-digested GTE and digested GTE without milk. Apparent permeability coefficients (P_app) of EGCG and ECG in digested GTE with 25% milk were significantly higher compared to those in GTE with 10% milk, and amounted to 2.41 × 10^− 6 cm/s and 1.39 × 10^− 6 cm/s. The recoveries of all catechins in GTE with milk in Caco-2 cells after 2 h incubation were significantly higher than that without milk. To summarize, these data suggest that milk addition may increase catechin bioavailability by enhancing their transepithelial absorption and uptake from green tea extract.     

Effect of pulsed electric fields on the structure and frying quality of “kumara” sweet potato tubers

The aim of this research was to study the effect of pulsed electric fields (PEF) on the microstructure of “kumara” sweet potato (Ipomoea batatas cv. Owairaka) and its quality after frying. Whole sweet potato tubers were treated at different electric field strengths ranging from 0.3 to 1.2 kV/cm with specific energy levels between 0.5 and 22 kJ/kg. Cell viability was determined using tetrazolium staining to investigate the uniformity of the PEF effect across tubers. Based on the patterns of viable cells it was observed that the effect of PEF was not homogeneous across the tuber. This result was also supported by the pattern of enzymatic browning due to PEF facilitating the reaction of polyphenoloxidase and phenols. PEF treatment resulted in significant softening of the ground tissues, but not on the dermal tissues, as determined by texture analysis. With respect to frying quality, tubers pre-treated with PEF at electric field strength of 1.2 kV/cm and fried at 190 °C had an 18% lower oil content than non-PEF treated samples. The kinetics of browning as a function of frying time could be described by a fractional conversion model. The activation energy (Ea) of the browning rate during frying increased (more temperature sensitive) due to PEF pretreatment at 0.5 kV/cm and 1.2 kV/cm. It implies that PEF pretreatment allows frying the potato chips at lower temperature in order to achieve the same brown colour intensity as the non-PEF treated tubers. This study shows clearly that PEF could reduce the energy required for cutting and frying of kumara.Industrial relevanceThis study provides evidence that the effect of PEF processing on whole kumara tubers is not uniform, demonstrating heterogenous distribution. These findings provide important information for food industry to design appropriate PEF processing conditions for solid materials. More importantly, PEF treatment reduced the energy required for cutting and frying of kumara, and reduced the oil content in the fried kumara chips.     

Effect of thermal treatment on the enzymatic hydrolysis of chicken proteins

The proteins of chicken breast meat were thermally treated in this work. Treatment temperature and time were chosen to evaluate the effect of thermal treatment. By determination of SH and S-S group levels, the results indicated that the SH and S-S group levels in the chicken proteins without thermal treatment were 65.06 and 12.29 μmol/g. With the increase of treatment temperature, the SH group level decreased, while S-S group level increased gradually. Enzymatic hydrolysis by Alcalase was done to evaluate the nitrogen levels of hydrolysates. A temperature-dependent effect was observed for soluble and formaldehyde nitrogen levels. A slight increase of peptide nitrogen level was found with the increase of temperature. Treatment time had a similar effect to treatment temperature. The molecular weight of chicken protein hydrolysates was analysed by gel permeation chromatography. The chicken protein hydrolysates without thermal treatment showed an apparent peak at 27.5 ml of elution volume and a weak peak at 4.0 ml, which represented fractions with molecular weight of > 10,000 Da and < 2640 Da, respectively. Thermal treatment led to decreases of the fractions with molecular weight of > 10,000 Da, 3500–2640 Da and < 2640 Da, compared with hydrolysate fractions without thermal treatment. Treatment with a temperature higher than 60 °C for 20 min would completely eliminate the > 10,000 Da fraction from chicken protein hydrolysates. The percentage of fraction with molecular weight of 4500–3500 Da increased with the extension of treatment time to 20 min, thereafter decreased.Industrial relevanceThe annual yield of chicken meat in China ranks the second of the world. However, the extensive development of this resource is still limited. In this work, chicken breast meat was thermally treated and then hydrolysed by Alcalase. Effects of treatment temperature and time on the hydrolysates were investigated. The results indicated that thermal treatment could change the levels of soluble nitrogen, formaldehyde nitrogen and peptide nitrogen. The area percentages of fractions with different molecular weight were also changed. This work was helpful to understand the characteristics of bioactive peptides produced from chicken proteins.     

Fat contributes to the buffering capacity of chicken skin and meat but enhances the vulnerability of attached Salmonella cells to acetic acid treatment

Chicken skin and chicken meat display different buffering effects which may impact the survival of Salmonella attached to them when treated with acids. This study investigated the role that differences in fat composition of chicken skin and meat play in their buffering capacity. The survival of Salmonella attached to chicken skin and meat in the presence of fat, and treated with acetic acid was also investigated. Fat was extracted from chicken skin and meat and the buffering capacities of chicken skin, meat, extracted fat and their respective remnants were determined. Two strains of Salmonella Typhimurium and two strains of S. Enteritidis were attached independently to each of the chicken component listed above and enumerated before and after treatment with 0.3 M acetic acid. Chicken skin has a higher fat content as compared to chicken meat. Skin (13 mmol H⁺/(pH1 kg)) had a stronger buffering capacity (p < 0.05) than the extracted fat alone and skin remnants alone (7.0 mmol H⁺/(pH 1 kg) and 6.9 mmol H⁺/(pH 1 kg) respectively). From an initial inoculum (~ 9 log CFU/g), Salmonella cells attached better (p < 0.05) to chicken meat (~ 8 log CFU/g) and chicken skin (~ 7 log CFU/g) than extracted fat (~ 1.5 log CFU/g). Skin remnants without fat were better (p < 0.05) at protecting attached Salmonella than other chicken components. For example S. Typhimurium ATCC 33062 decreased ~ 1 log CFU/g (p < 0.05) on skin remnants after acetic acid treatment while its viable counts on other components decreased from ~ 1.5 to 7 log CFU/g (p < 0.05). We suggest that the fat content present in the skin may enhance the vulnerability of attached cells to acetic acid.     

Quality changes of ready-to-eat ginseng chicken porridge during storage at 25 °C

Ready-to-eat (RTE) ginseng chicken porridge was heated in a retort with an F-value of 4.0 after being packaged in a gas-tight plastic tray (PP/EVOH/PP) with top film (PET/PA/CPP). Various quality changes were investigated during the storage for 28 weeks at 25 °C. Over the storage period, microorganisms were not detected above 1.0 log cfu/cm² (detection limit). The viscosity increased sharply from 775 to 2025 cp for initial 4 weeks and increased steadily until 16 weeks, with a slight reduction thereafter. During the 28 weeks of storage, the ratio of residual oxygen and pH decreased from 10.8% and 6.49 to 5.7% and 6.05, while retrogradation degree increased from 0% to 55.9%. Hunter L^⁎, b^⁎, and ΔE values increased until 20 weeks and remained for the rest of storage. Based on sensory, microbiological and physicochemical evaluations, the RTE ginseng chicken porridge could be marketable for at least 24 weeks at 25 °C.     

Colour photographs for estimation of heterocyclic amine intake from fried pork chops of different RN genotypes indicate large variations

A questionnaire complemented with colour photographs was used to obtain information on dietary practices and preferences regarding home-prepared pork chops in a small (n=151) sample of Swedish consumers. The results from the questionnaire were combined with analytical results from meat of different RN genotypes, and showed that fried chops from a pig that was carrying the RN⁻ allele (high glycogen content) had a darker crust and contained lower levels of mutagenic heterocyclic amines (HCAs) than chops from a non-carrier (low glycogen content). In this study population, the intake of fried pork chops only contributed slightly to the total HCA exposure; the total monthly intake of mutagenic HCAs was on average 256 ng, ranging from 0 to 1982 ng/month. However, using lower frying temperatures and meat from pigs carrying the RN⁻ allele can further reduce the intake. From the photographs, most of the respondents chose fried chops from the non-carrier, which would result in an average contribution to the monthly HCA intake of 359 ± 402 ng (mean ± SD) compared to 35 ± 60 ng/month for consumers who preferred the RN⁻/rn⁺ chops. More than 20 times the amount of mutagenic HCAs was formed when frying chops of the non-carrier of the RN⁻ allele at an initial pan temperature of 200 °C instead of 160 °C; 4.13 compared to 0.18 ng/g cooked meat.