Bacteriological Survey of the Frozen Prepared Foods Industry: IV. Frozen Breaded Fish

During sanitation-inspections of 23 breaded-fish processors, 573 finished product units and 604 line samples were collected and analyzed bacteriologically. Data for finished product units processed on the same data are presented in groups; most of the groups consisted of 10 units. Groups of frozen, raw-breaded fish produced under good and poor conditions of sanitation were studied. No more than 20% of the units in each group produced under good conditions of sanitation were positive for Escherichia coli or coagulase-positive staphylococci. Groups of frozen, fried-breaded fish produced under good and poor sanitary conditions were also studied. No more than 10% of the units in each good-sanitation group were positive for E. coli or coagulase-positive staphylococci. However, approximately 30% of the groups processed under poor sanitary conditions also did not exceed these viable bacterial counts because of the lethal effect of the terminal fry to which the product is subjected. It was found that line samples collected from the processing lines reflected the sanitary conditions of the plant and provided bacteriological support for inspectional evidence of plant insanitation.     

Alleviation of low temperature sweetening in potato by expressing Arabidopsis pyruvate decarboxylase gene and stress-inducible rd29A: A preliminary study

The acceptability of potatoes for processing chips and French fries is largely dependent on the color of the finished product. Most potato cultivars and varieties stored at temperatures below 9–10 °C are subjected to low temperature sweetening (LTS) which result in the production of bitter-tasting, dark colored chips and French fries which are unacceptable to consumers. However, storing tubers at low temperatures (i.e., <10 °C) has many advantages such as lowered weight loss during storage, natural control of sprouting, and reduction/elimination of chemical sprout inhibitors. Our earlier research results on LTS suggested a role for pyruvate decarboxylase (PDC) in LTS-tolerance. In the present study, the role of PDC was examined whereby the potato variety Snowden was transformed with Arabidopsis cold-inducible pyruvate decarboxylase gene 1 (AtPDC1) under the control of promoter rd29A. Two transgenic plants were selected and storage studies were conducted on tubers harvested from one of the transgenic lines grown under green house conditions. Transgenic tubers showed higher Agtron chip color score indicating lighter chip and lower reducing sugar and sucrose concentrations compared to the untransformed tubers during the storage periods studied at 12 °C and 5 °C. These results suggest that overexpression of pyruvate decarboxylase gene resulted in low temperature sweetening tolerance in the transgenic Snowden.     

An overview of the factors affecting sugar content of potatoes

Potatoes destined for making chips, French fries and other fried products, need to have low sugar content to avoid browning of the finished product. The sugar content of potatoes is determined by the genotype and several pre‐ and post‐harvest factors. The major pre‐harvest factors affecting sugar content are crop maturity, temperature during growth, mineral nutrition and irrigation, while important post‐harvest factors are mechanical stresses and storage conditions. Each genotype requires an ideal pre‐and post‐harvest treatment to maintain low sugar levels; any kind of stress results in sugar accumulations.     

Bacteriological Survey of the Blue Crab Industry

During sanitation inspections of 46 crabmeat processing plants on the Atlantic and Gulf Coasts, 487 samples of whole crabs immediately after cooking, cooked crabs after cooling, backed or washed (or both) crab bodies and whole crab claws, as well as 1,506 retail units of finished product were collected and analyzed bacteriologically. The 1,506 retail units (1-lb [373.24-g] cans) included 518 cans of regular (special) meat, 487 cans of claw meat, and 501 cans of lump meat. Statistical analyses showed that crabmeat from plants in Mississippi, Louisiana, and Texas had higher counts in 19 of 24 cases for the four bacteriological indices than crabmeat from plants located along the Atlantic Coast and the Gulf Coast of Florida. Aerobic plate counts of retail units collected from a previous day's production were significantly higher than those collected on the day of inspection. Regular crabmeat had consistently higher aerobic plate counts than claw or lump meat. When the product was handled expeditiously under good sanitary conditions, the bacteriological results were significantly better than the results from plants operating under poor sanitary conditions. Crabmeat produced in plants operating under good sanitary conditions had the following bacteriological content: (i) coliform organisms average most-probable-number values (geometric) of less than 20 per g; (ii) no Escherichia coli; (iii) coagulase-positive staphylococci average most-probable-number values (geometric) of less than 30 per g in 93% of the plants; (iv) aerobic plate count average values (geometric) of less than 100,000 per g in 93% of the plants, with the counts from 85% of these plants below 50,000 per g.     

Bacteriological Survey of the Frozen Prepared Foods Industry: II. Frozen Breaded Raw Shrimp

During inspection of 21 frozen breaded raw shrimp processors, 861 finished product units (retail packages) and 778 line samples were collected and analyzed bacteriologically. The bacteriological results for the finished product samples collected in plants with poor and good sanitary controls are presented and compared. The samples consisted of 4 to 38 units (retail packages) of the finished product as offered for sale by the processors. Frozen raw breaded shrimp collected from plants operating under good conditions of sanitation had the following bacterial contents: 85% of the samples had an average (geometric) aerobic plate count of less than 1,000,000 per gram; all of the samples had an average (geometric) most probable number of less than 1,000 coliforms per g; 81% of the samples contained less than 20% Escherichia coli-positive units; 57% of the total number of units in 0.1-g portions were negative for coagulase-positive staphylococci, and 95% of the units had less than 1,000 coagulase-positive staphylococci per gram.     

Bacteriological Survey of Frozen Meat and Gravy Produced at Establishments Under Federal Inspection

During visits to 34 federally inspected establishments producing frozen meat and gravy, 541 production line samples and 535 finished product units were collected for bacteriological analyses. It was found that more than 70% of the sets of finished product (10 units/set) produced under good manufacturing practices had: (i) four or fewer coliform-positive units, (ii) two or fewer Escherichia coli-positive units, (iii) three or fewer Staphylococcus aureus-positive units, and (iv) an aerobic plate count of fewer than 50,000/g (geometric mean of 10 units). All finished product units were negative for salmonellae.     

Acrylamide in processed potato products: progress made and present status

Concerns related to higher levels of acrylamide in processed carbohydrate-rich foods, especially in fried potato products, are well known. This article provides updates on various aspects of acrylamide in processed potato products including mechanisms of acrylamide formation and health risks due to its intake. Levels of reducing sugars in potatoes are considered as a main factor contributing towards the formation of acrylamide in processed potato products. Useful approaches in lowering the levels of reducing sugars such as use of suitable varieties, storage methods, storage temperature and duration of storage are described and discussed. Importance and practical utility of various steps before and during the processing that can contribute in reducing the final concentration of acrylamide are highlighted. Progress made and present status of potato processing industry in India are part of this article. The article describes varietal improvement and spread of short-term and long-term storage technologies in India and their contribution towards round the year availability of processing-grade potatoes to the processing industries and how all this has helped in achieving reduced levels of acrylamide in chips and French fries. Outcome and implications of cold-induced sweetening tolerance in potatoes are presented along with other management practices and strategies that can lower the acrylamide levels in processed potato products. Future lines of work have been suggested to make the consumption of fried potato products safer.     

Bacteriological Survey of the Frozen Prepared Foods Industry: I. Frozen Cream-Type Pies

During Food and Drug Administration inspections of 12 imitation cream pie producers, 453 finished product samples and 350 line samples were collected and analyzed bacteriologically. Sanitary conditions in the plants varied from good to poor and, in general, were reflected in the bacteriological results. The survey revealed that, in the great majority of cases, frozen imitation-cream pies produced in plants operating under good conditions of sanitation had the following bacteriological content: (i) a most probable number (MPN) of fewer than three Escherichia coli cells per gram (i.e., absent from all tubes in the methodology employed), (ii) an average MPN of fewer than 50 coliforms per gram (10 or more pies), (iii) the absence of coagulase-positive staphylococci in 0.1-g portions, and (iv) an aerobic plate count of fewer than 25,000 per gram (geometric mean of 10 or more pies).     

Low-acrylamide French fries and potato chips

SUMMARY: Acrylamide is produced in starchy foods that are baked, roasted or fried at high temperatures. Concerns about the potential health issues associated with the dietary intake of this reactive compound led us to reduce the accumulation of asparagine, one of its main precursors, in the tubers of potato (Solanum tuberosum). This metabolic change was accomplished by silencing two asparagine synthetase genes through 'all-native DNA' transformation. Glasshouse-grown tubers of the transformed intragenic plants contained up to 20-fold reduced levels of free asparagine. This metabolic change coincided with a small increase in the formation of glutamine and did not affect tuber shape or yield. Heat-processed products derived from the low-asparagine tubers were also indistinguishable from their untransformed counterparts in terms of sensory characteristics. However, both French fries and potato chips accumulated as little as 5% of the acrylamide present in wild-type controls. Given the important role of processed potato products in the modern Western diet, a replacement of current varieties with intragenic potatoes could reduce the average daily intake of acrylamide by almost one-third.     

Vacuolar Invertase Gene Silencing in Potato (Solanum tuberosum L.) Improves Processing Quality by Decreasing the Frequency of Sugar-End Defects

Sugar-end defect is a tuber quality disorder and persistent problem for the French fry processing industry that causes unacceptable darkening of one end of French fries. This defect appears when environmental stress during tuber growth increases post-harvest vacuolar acid invertase activity at one end of the tuber. Reducing sugars produced by invertase form dark-colored Maillard reaction products during frying. Acrylamide is another Maillard reaction product formed from reducing sugars and acrylamide consumption has raised health concerns worldwide. Vacuolar invertase gene (VInv) expression was suppressed in cultivars Russet Burbank and Ranger Russet using RNA interference to determine if this approach could control sugar-end defect formation. Acid invertase activity and reducing sugar content decreased at both ends of tubers. Sugar-end defects and acrylamide in fried potato strips were strongly reduced in multiple transgenic potato lines. Thus vacuolar invertase silencing can minimize a long-standing French fry quality problem while providing consumers with attractive products that reduce health concerns related to dietary acrylamide.     

Microbiological quality of five potato products obtained at retail markets

The microbiological quality of frozen hash brown potatoes, dried hash brown potatoes with onions, frozen french fried potatoes, dried instant mashed potatoes, and potato salad was determined by a national sampling at the retail level. A wide range of results was obtained, with most sampling units of each products having excellent microbiological quality. Geometric mean aerobic plate counts were as follows: dried hash brown potatoes, 270/g; frozen hash brown potatoes with onions, 580/g; frozen french fried potatoes 78/g; dried instant mashed potatoes, 1.1 x 10(3)/g; and potato salad, 3.6 x 10(3)/g. Mean values of coliforms, Escherichia coli, and Staphylococcus aureus were less than 10/g.     

Microbiological quality of five potato products obtained at retail markets.

The microbiological quality of frozen hash brown potatoes, dried hash brown potatoes with onions, frozen french fried potatoes, dried instant mashed potatoes, and potato salad was determined by a national sampling at the retail level. A wide range of results was obtained, with most sampling units of each products having excellent microbiological quality. Geometric mean aerobic plate counts were as follows: dried hash brown potatoes, 270/g; frozen hash brown potatoes with onions, 580/g; frozen french fried potatoes 78/g; dried instant mashed potatoes, 1.1 x 10(3)/g; and potato salad, 3.6 x 10(3)/g. Mean values of coliforms, Escherichia coli, and Staphylococcus aureus were less than 10/g.     

Microbiological Evaluation of Cold-Water Shrimp (Pandalus borealis)

A bacteriological survey of the Maine shrimp industry was conducted to investigate the conditions associated with the production of frozen, raw, peeled shrimp. In-plant samples and finished product units were collected from seven plants. The most probable number of Escherichia coli, coliforms, and coagulase-positive staphylococci, as well as aerobic plate counts (APC), were determined. Freshly harvested shrimp collected from fishing vessels had an APC geometric mean of 510/g, and E. coli, coliforms, and coagulase-positive staphylococci were absent. Subsequent storage and insanitary practices during processing increased the APC and introduced coliforms. However, the low air temperatures (18 to 45 F) in the plants and the large volumes of cold water (34 F) used during processing inhibited significant bacterial buildup in the finished product.     

THE SUSCEPTIBILITY OF POTATO VARIETIES TO INFESTATION BY THE EELWORMS DITYLENCHUS DESTRUCTOR AND D. DIPSACI

Twenty-five varieties of potato in common commercial cultivation were found to be susceptible to tuber attack by potato-derived populations of Ditylenchus destructor under field and pot experimental conditions. Stunting and leaf deformation may also be caused by the eelworms but appear less consistently. A race of D. destructor from mushroom spawn had almost no effect on potatoes. Various races of D. dipsaci can reproduce in the shoot tissue of potato, sometimes causing damage. One population of this stem eelworm produced lesions on the tubers.     

Engineering and biotechnological aspects for the manufacturing of high quality fried potato products

Fried potato products have become very popular foods over the last decades. High quality standards have been established for these products by the food industry including uniform brown color and crispness. During frying, Maillard reactions takes place which contribute to color and taste development in these products. However, safety aspects are also influenced by these reactions, e.g., acrylamide formation. Maintaining high safety standards as well as the expected quality requires systematic research based on an integrated approach including all relevant variables, e.g., raw material properties, processing conditions and equipment concepts. Selected results of these investigations are presented and discussed, regarding influence of composition, e.g., precursor levels for Maillard reactions, treatment of raw materials and addition of reactants to frying fat. It has been demonstrated that a combined treatment of the potato sticks by coating of product surfaces and partial pre-drying can be successfully applied to produce well-browned French fries with lower acrylamide contents. Reductions up to 75% could be reached compared to samples without treatment. Furthermore, addition of a water/oil emulsion containing glutamine in the aqueous phase has been shown to influence Maillard reactions at the product surface, resulting in lower acrylamide contents at the same state of browning.     

Occurrence of thermotolerant campylobacters in fresh vegetables sold at farmers' outdoor markets and supermarkets.

A total of 1564 fresh samples of 10 vegetable types from two different retail levels (533 samples from farmers' outdoor markets and 1031 samples from supermarkets) were surveyed for the occurrence of thermotolerant campylobacters. In samples from the outdoor markets, campylobacters were detected on six types of vegetables; the detection rates were spinach, 3.3; lettuce, 3.1; radish, 2.7; green onions, 2.5; parsley, 2.4; and potatoes, 1.6%. Campylobacter jejuni was the predominant species (88%), with the remainder being C. lari (8%) and C. coli (4%). When the outdoor market samples were thoroughly washed with chlorinated water, all were negative for campylobacters. Of the samples from supermarkets, all were negative for campylobacters whether purchased in summer or winter. These results suggest that vegetables sold at farmers' outdoor markets are produced and (or) stored under less sanitary conditions than those sold at supermarkets, and they could constitute health hazards. Therefore, vegetables (e.g., potatoes and spinach) from farmers' markets must be decontaminated by washing with chlorinated water or cooked thoroughly before consumption.     

Acrylamide in food: Progress in and prospects for genetic and agronomic solutions

Acrylamide is a processing contaminant and Group 2a carcinogen that was discovered in foodstuffs in 2002. Its presence in a range of popular foods has become one of the most difficult problems facing the food industry and its supply chain. Wheat, rye and potato products are major sources of dietary acrylamide, with biscuits, breakfast cereals, bread (particularly toasted), crispbread, batter, cakes, pies, French fries, crisps and snack products all affected. Here we briefly review the history of the issue, detection methods, the levels of acrylamide in popular foods and the risk that dietary acrylamide poses to human health. The pathways for acrylamide formation from free (non‐protein) asparagine are described, including the role of reducing sugars such as glucose, fructose and maltose and the Maillard reaction. The evolving regulatory situation in the European Union and elsewhere is discussed, noting that food businesses and their suppliers must plan to comply not only with current regulations but with possible future regulatory scenarios. The main focus of the review is on the genetic and agronomic approaches being developed to reduce the acrylamide‐forming potential of potatoes and cereals and these are described in detail, including variety selection, plant breeding, biotechnology and crop management. Obvious targets for genetic interventions include asparagine synthetase genes, and the asparagine synthetase gene families of different crop species are compared. Current knowledge on crop management best practice is described, including maintaining optimum storage conditions for potatoes and ensuring sulphur sufficiency and disease control for wheat.     

The characteristics of certain varieties of potato with special reference to their suitability for drying

There is considerable varietal variation in the characteristics of the potato. The characteristics of any one variety of potato may be very greatly modified by environmental conditions. Rainfall and percentage dry matter may be inversely correlated, as may rainfall and yield in localities with a medium or high precipitation. There is an apparent correlation between time of maturity, percentage dry matter, and texture when cooked, late varieties having a higher percentage dry matter and a more floury texture than early varieties. It is a fundamental requirement of potatoes for drying purposes that they should not discolour on cooking. In addition the texture of the cooked potato should be suitable for the method of drying employed, and for the type of reconstituted product desired, and the percentage dry matter should be as high as is compatible with the foregoing conditions.     

Study on potato virus M (PVM) occurrence in potato fields in Iran

57 native potato tuber samples collected from different potato growing region of Iran, planted on single rows in Karaj College experimental station. Plant samples of each single row plus 9.25 Fresh foliage samples collected from fields under new introduced cultivars were tested for potato virus (PVM) infection during growing season. Also 78 weeds and field crops belonging to Solonacae and Leguminosae from or neighboring to potato field were tested. Results indicated that PVM was not found on any plant other than potatoes. PVM was detected on 16 samples of 57 old vars, Virus was not seen in any samples collected from fields under new varieties. Results show that PVM is limiting in this crop. PVM detecting is difficult using assay hosts. Best test plants were French bean var Red kidney, Showing pinpoint necrotic LL, also Datura metel and Nicotiana debneyi are useful for virus detection showing chlorotic local lesion. Also microprecipition and gel diffusion test can be used for virus detection but Elisa was the best method. PVM infected plant showed 11-19.5 percent yield decrease in 3 cultivars tested.