Effects of Frying Procedures and Compositional Factors on the Temperature Profile of Bacon

ArticleinJournal of Food Science 48(3):817 - 819 · August 2006with 6 Reads
Cite this publication
Abstract
The effects of frying procedures (preheated vs cold skillet) and compositional factors (adipose vs lean) on the final temperatures attained in fried bacon were investigated as a prelude to studying the kinetics of N-nitrosopyrrolidine formation in bacon. With a preheated skillet set at 171°C, the final temperature reached in whole bacon samples at the end of the 6 min frying time was 164 ± 3°C. Bacon samples, initially placed in a cold skillet preset to heat to 171°C, attained temperatures of 127 ± 5°C and 165 ± 6°C at the end of 6 and 8 min frying periods, respectively. It was observed that the lean bacon strips rarely exceeded 145°C while the adipose approached 165°C when separated adipose and lean components from whole bacon samples were fried for 6 min in a preheated (171°C) skillet.

Do you want to read the rest of this article?

Request Full-text Paper PDF
  • Article
    A selection of the main factors influencing the quality of microwave pre-cooked streaky and back bacon were investigated. Processing parameters were initially investigated using a domestic microwave oven. It was found that the power-output, heating time and position within the oven had a greater influence on the resulting product, in terms of weight loss, than the composition of the bacon. Positioning the bacon 43mm above the turntable of the oven and heating streaky at 1000W for 3min and back at 500W for 5min achieved the best results. This resulted in a mean weight loss of 64.1% and 55.2% for streaky and back respectively. The temperatures reached during cooking (100–145°C) were sufficient to pasteurise the bacon.Further trials were carried out using a pilot-scale industrial microwave-cooking tunnel. The optimum processing condition for both types of bacon was found to be 6kW for 115s. This condition provided more uniform heating and resulted in lower weight losses (51.9% streaky, 38.3% back) than were found in the domestic oven whilst producing bacon of similar organoleptic quality. Storage trials showed that bacon produced under this condition had a shelf life of between 11 and 14 days when stored in vacuum packs at 4°C.
  • Article
    Thirty-nine fried bacon samples and corresponding fried-out fats were collected from randomly selected consumers' homes. Bacons were purchased and cooked in the course of preparing meals containing bacon. The average volatile N-nitrosamine content μg/kg) of the rasher and fried-out fat, respectively, were: N-nitrosodimethylamine, 4.0 and 5.3; N-nitrosopiperidine, 0.7 and 1.5; N-nitrosopyrrolidine, 17 and 32; N-nitrosothiazolidine, 8.9 and 3.4. The average daily ingestion of N-nitrosopyrrolidine from bacon for our survey respondents was estimated to be 76 ng/person/day. A majority of respondents indicated that they used the fried-out fat as a cooking oil.
  • Article
    Use of microwaves has increased largely in the domestic household in the last few decades due to the convenience of using microwave ovens. In the industrial sector, microwave processing is used in some of the unit operations, while it is yet to capture a major place in the industrial applications. The major drawback associated with microwave heating is the non-uniform temperature distribution, resulting in hot and cold spots in the heated product. The non-uniform temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms may not be destroyed in the cold spots. The temperature distribution during microwave heating has been studied in a wide variety of products by several researchers. This paper summarizes their results and the solutions offered by them to lessen the non-uniformity of heating. The current applications of microwave energy in the industrial sector are also highlighted.
  • Article
    Whole bacon rashers and the separated lean and fat components were fried in an electrically heated pan and the residues in the pan and the trapped cooking vapours analysed for N-nitrosopyrrolidine and N-nitrosodimethylamine. The fat produced 12 times more N-nitrosopyrrolidine and six times more N-nitrosodimethylamine than the lean. In all cases the largest proportions of both nitrosamines were recovered from the cooking vapours. Prolonged heating of lean did not increase amounts of the nitrosamines. The importance of the non-polar lipid phase of the adipose tissue in nitrosamine formation was demonstrated by heating fat and lean components of bacon in a non-polar heating medium when high levels of nitrosamines were produced from the lean as well as the fat.
  • Effect of nitrite and other factors on the physicochemical characteristics and nitrosamine formation in bacon
    • H K Herring
  • Article
    Fried bacon samples prepared with 0-, 50-, 100-, 150-, and 200-ppm levels of sodium nitrite were analyzed for nitrosopyrrolidine and dimethylnitrosamine. The samples prepared without any added nitrite were negative, but all the fried samples with added nitrite contained detectable levels (2-20 ppb) of nitrosamines. The levels of nitrosopyrrolidine correlated well with the initial concentrations of nitrite but not with that of nitrite found in the raw bacon just prior to frying, The identity of nitrosopyrrolidine in a few samples was confirmed by glc-mass spectrometry.
  • Article
    Randomized slices of bacon were cooked at home by 25 consumers by their usual method of preparation and the edible portions were analyzed for nitrosamines. N-nitrosodimethylamine (DMNA) and N-nitrosopyrrolidine (NPyr) were found in all samples. Of the 25 preparations, five contained DMNA and five contained NPyr in concentrations greater than 10 μg/kg; only one sample contained both nitrosamines in concentrations greater than 10 μg/kg. Although the association between nitrosamine concentration, time and amount of heat is not strong, it appears that frying bacon at low or medium heat for less than 10 min can result in less than 10 μg/kg DMNA or NPyr.
  • Article
    Nitrosopyrrolidine (NO-Pyr) formation in bacon is primarily dependent on frying temperature and not time. Cooking methods affect the amount of NO-Pyr formed: pan frying produces the highest level of NO-Pyr with variable concentrations formed on baking, broiling and cooking in a “baconer.” Microwave oven treatment produced the lowest amount of NO-Pyr. A model system study of the decarboxylation of nitrosoproline shows this precursor, which may be present in bacon, is maximally converted to NO-Pyr at 185°C near the recommended temperature for frying.
  • Article
    The role of proline and putrescine as precursors of N-nitrosopyrrolidine was investigated in model and pork systems containing 150 and 1000 ppm of sodium nitrite. Both compounds increased the levels of N-nitrosopyrrolidine formed. However, it was concluded from the concentrations of proline and putrescine used in the study that the former was the more likely precursor of N-nitrosopyrrolidine in bacon. The distillate (condensate) collected on heating nitrite-treated pork samples in a heating flask was examined for its N-nitrosopyrrolidine content. Approximately 27–49% of the total N-nitrosopyrrolidine produced was volatilized during the cooking process.
  • Article
    SummaryA simple model system has been developed which mimics the formation of the principal nitrosamine, N-nitrosopyrrolidine, in grilled or fried bacon. The yield of the nitrosamine in the model system may be estimated by a simple GC method. This has permitted the rapid screening of a variety of compounds which may influence nitrosamine in bacon. The antioxidant ethoxyquin inhibits nitrosamine formation in the model system.
  • Article
    The kinetics of reactions such as the nitrosation of proline or pyrrolidine and the decarboxylation of proline or N-nitrosoproline in heated model systems simulating the pan-frying conditions of bacon were determined. The rate constants, half-life values and activation energy values of these reactions were calculated. The nitrosation of proline or pyrrolidine in adipose model systems occurs readily in the temperature range 80–160°C, while the decarboxylation of proline or N-nitrosoproline proceeds only at 100°C or above. The rates of the above reactions are such that nitrosation of proline > nitrosation of pyrrolidine > decarboxylation of proline or N-nitrosoproline. Results lend credence to the pathway involving N-nitrosoproline in the formation of N-nitrosopyrrolidine in bacon.
  • Article
    The presence of N-nitrosopyrrolidine in cooked bacon has aroused considerable interest as to its precursor. This study investigated the effect of storage at 2°C on the concentration of free proline in green pork bellies and the separated lean and adipose tissues. Prolonged storage up to 28 days resulted in the expected increase in the free amino acid concentration. Proline in the whole pork belly increased approximately 45% after 1 week of storage, while over the same period, the free proline content in the lean and adipose tissues increased 33 and 86%, respectively.RésuméLa présence de N-nitrosopyrrolidine dans le lard fumé, cuit a soulevé un grand intérêt, particulièrement a l'égard de son éventuel précurseur. Cette étude démontre l'effet de l'entreposage à 2°C sur la concentration en proline libre dans la chair, dans la partie adipeuse et dans le flanc complet de porc frais. Un entreposage allant jusqu'à 28 jours augmente la concentration en acides aminés libres. Le contenu en proline libre dans le flanc entier augmente de 45% en une semaine d'entreposage; dans ce même laps de temps, la concentration en proline libre dans la chair et les tissus adipeux augmente respectivement de 33% et 86%.
  • Article
    ABSTRACTN-Nitrosopyrrolidine (NPYR) has been detected and confirmed at the ppb level in a significant number of fried bacon samples. N-Nitrosoproline (NPRO) has been assumed to be the primary precursor of NPYR, but there are conflicting reports about its precise role. A method was developed for determining NPRO and a survey of 60 cured meat samples was conducted. No NPRO was detected in uncooked, conventionally cured bacon, Canadian bacon, ham, salt pork, pork roll or pastrami. NPRO was detected and confirmed in 1 of 7 dry cured bacon samples (106 ppb), 8 of 12 dry cured ham samples (18-604 ppb), and 5 of 6 samples of pork side meat (86-411 ppb). The results suggest the NPRO may not be the main precursor of NPYR in bacon, but may have a role in nitrosamine formation in dry-cured products.
  • Article
    A new rapid method for the cell cycle analysis of asynchronously growing cells is presented. The new method is an alternative to the more time consuming and subjective fraction of labeled mitoses (FLM) method. Like the FLM method, all cells in the S phase of the cell cycle are marked by pulse labeling with a radioactive DNA precursor. The subsequent progress of the cohort of cells thus labeled is monitored through a narrow window in the cell cycle. The window is defined by a narrow range of DNA contents corresponding to cells in mid-S phase and is designated Si. The cellular DNA content is measured by flow cytometry and the cells in the window Si are selected by electronic cell sorting. The radioactivity per cell in Si (RCSi) is determined by liquid scintillation counting. The duration of S phase and of the total cycle and the dispersions therein are determined from the oscillation of the RCSi values with time. The complete cell cycle analysis can be accomplished in as little as 1 day following the collection of samples. Exponentially growing Chinese hamster ovary (CHO) cells were analyzed according to the RCSi method and the FLM method. It is demonstrated that the two techniques give essentially the same results.
  • Article
    Nitrosoproline (NPro) has been suggested as a precursor of nitrosopyrrolidine (NPyr) in fried bacon. We have developed a procedure for isolation of NPro from raw bacon for subsequent chromatographic analysis. Analysis has been done by both gas and high-performance liquid chromatography. The two methods have included different specific detectors. Results indicate that preformed NPro is not a major source of NPyr.
  • Article
    A method for the isolation and detection by gas chromatography of nitrosamino acids in foods has been developed: of 30 cured meat products examined, only two contained more than 100 ppb (b = 109) of a nitrosamino acid. The heat-induced decarboxylation of N-nitrososarcosine, N-nitrosoproline and N-nitroso-4-hydroxyproline was investigated. In silicone oil at 230°C, N-nitrosodimethylamine was formed at 90% of theoretical yield and N-nitrosopyrrolidine and N-nitroso-3-hydroxypyrrolidine were formed at 11 and 9% of theoretical yield, respectively. Frying ham in an open pan gave less than 3% of the theoretical yield for all nitrosamines. During the frying process, about 80% of the N-nitrosodimethylamine, 50% of the N-nitrosopyrrolidine and 5% of the N-nitroso-3-hydroxypyrrolidine formed were volatilized in the fumes. The data obtained clearly indicate that the decarboxylation of nitrosamino acids is not the essential pathway of nitrosamine formation during the frying of cured meat products.
  • Article
    Evidence is presented to show that N-nitrosopyrrolidine in cooked bacon arises by decarboxylation of N-nitrosoproline formed very likely by radical nitrosation of free proline in pork belly. A method for measuring N-nitrosoproline in raw bacon is described.
  • Article
    Experiments involving 14C-labeled amines have shown that proline is more likely to be the precursor of nitrosopyrrolidine formation than either spermidine or putrescine in fried bacon. The data are consistent with a mechanism involving formation of nitrosoproline from sodium nitrite and free proline during processing with subsequent decarboxylation of nitrosoproline during frying.
  • Article
    Hitherto unknown long-chain acetals of ascorbic and erythorbic acids have been found to be excellent blocking agents for nitrosamine formation in bacon. Unlike ascorbyl palmitate, which tends to lose its activity on storage, the acetals retain their efficacy in bacon even after 35 days at +3 °C.
  • Article
    An improved method is described for determining volatile N-nitrosamines in rendered bacon grease at the part-per-billion level. A distillation aid comprised of silica gel and kaolin greatly improves N-nitrosamine recoveries for the mineral oil distillation procedure. The N-nitrosamines are analyzed by gas chromatography with a Thermal Energy Analyzer detector. This procedure is a fast, selective, and reliable method for determining N-nitrosamines in bacon grease.
  • Article
    The effect of pork belly storage on nitrosopyrrolidine (NPYR) formation in fried bacon was investigated. Bacon made from fresh bellies produced significantly less (p < 0.05) NPYR than that made from bellies that had been either stored for 1 week in a refrigerator or frozen for 3 months and then thawed prior to use. Bellies thawed in water produced less NPYR than bellies thawed in a refrigerator or at room temperature. A high correlation (p < 0.01) between residual nitrite and NPYR was also observed.