Salmonellae, salmonellosis, and dairy foods: a review.

Salmonellae continue to be a major concern for the dairy industry because these bacteria have caused recent outbreaks of illness and have been isolated from various dairy products in the market place. Salmonellae are generally not heat resistant and normally grow at 35 to 37 degrees C, but they can grow at much lower temperatures, provided that the incubation time is suitably extended. To minimize problems, foods should be held at or below 2 to 5 degrees C at all times. Both conventional and rapid methods are available to isolate salmonellae from dairy foods and to identify the bacteria. Salmonellae behave differently in different kinds of cheese: they survived in ripening Cheddar cheese for up to 7 mo at 13 degrees C and for 10 mo at 7 degrees C; in coldpack cheese food for several weeks, depending on the pH and preservative used; and in Domiati cheese 13 to 36 d, depending on the manufacturing process used. When Mozzarella cheese was made, temperatures of stretching and molding (60 degrees C) killed all salmonellae present, but, in cottage cheese, survival of the pathogen depended on the cooking temperature of curd. Spray drying of skim milk killed substantial numbers of salmonellae, but some survivors remained. Butter readily supported growth of salmonellae at room temperature, and neither freezing nor refrigeration for brief periods eliminated salmonellae from butter. Use of appropriate hygienic procedures, e.g., Hazard Analysis Critical Control Point system, during processing should reduce the likelihood of salmonellosis outbreaks associated with dairy foods.     

Toxic oxygenated alpha,beta-unsaturated aldehydes and their study in foods: a review

The oxidation of lipids containing polyunsaturated omega-3 or omega-6 acyl groups, such as docosahexenoic, eicosapentenoic, linolenic, arachidonic, or linoleic groups, and of the corresponding fatty acids, generates among other compounds alpha,beta -unsaturated aldehydes supporting different functional groups containing oxygen, which can be named oxygenated alpha,beta -unsaturated aldehydes (OalphabetaUAs). These compounds can be produced in cells and tissues of living organisms or in foods during processing or storage, and from these latter can be absorbed through the diet. In the last few years, OalphabetaUAs are receiving a great deal of attention because they are being considered as possible causal agents of numerous diseases, such as chronic inflammation, neurodegenerative diseases, adult respiratory distress syndrome, atherogenesis, diabetes, and different types of cancer. This review deals with the nature of the different kinds of OalphabetaUAs detected until now, their reactivity and consequent biological activity; the several pathways proposed for their formation; the current knowledge about the influence of both oxidative conditions and lipids nature in the rate of formation and yield of each kind of OalphabetaUAs in edible oils; the methods described until now to determine the presence in foods of some of these compounds, such as 4-hydroxy-trans-2-nonenal, 4-hydroxy-trans-2-octenal, 4-hydroxy-trans-2-hexenal and 4-oxo-trans-2-hexenal; and finally, the levels found of some of them in several foods.     

Effects of pesticides on sporulation of Cyclospora cayetanensis and viability of Cryptosporidium parvum

Disease outbreaks caused by the coccidian parasite Cyclospora cayetanensis in food have been linked to consumption of raspberries that may have been contaminated through exposure to water mixed with insecticides and fungicides that may have been sprayed onto the berries. Three different fungicides (captan 50% W.P., benomyl 50% W.P., and zineb 75% W.P.) and two different insecticides (malathion 25% W.P. and diazinon 4E 47.5%) were evaluated at five different concentrations and for exposure times of 30 min to 1 week. Sporulation of C. cayetanensis did not decrease with use of any of the pesticides from time periods of 30 min to 24 h at all concentrations. Sporulation percentage was reduced with the fungicide benomyl at 1 week of exposure. The growth of the parasite Cryptosporidium parvum was also evaluated using captan 50% W.P., benomyl 50% W.P., and diazinon 4E 47.5%. Oocyst infectivity was reduced only after 7 days of exposure. These results indicate that these pesticides used at recommended concentration levels do not affect the sporulation of Cyclospora.     

Antioxidants in lipid foods and their impact on food quality

This paper reviews the antioxidant properties of tocopherols and ascorbic acid in edible oils, and the impact of interfacial phenomena on their activities in emulsions and the effects of edible oil processing. Tocopherols are the most important natural antioxidants found in vegetable oil-derived foods. These antioxidants can interrupt lipid autoxidation by interfering with either the chain propagation or the decomposition processes. α-Tocopherol at high concentrations inhibits hydroperoxide decomposition but promotes hydroperoxide formation. The effect of antioxidants in inhibiting hydroperoxide decomposition may thus be critical in preserving food quality by reducing rancidity due to aldehyde formation. Ascorbic acid can regenerate α-tocopherol, inactivate metal initiators and reduce hydroperoxides. The activity of natural antioxidants is greatly affected by complex interfacial phenomena in emulsions and multi-component foods. In an oil-in-water emulsion system, the lipophilic antioxidants α-tocopherol and ascorbyl palmitate are more effective than in bulk oil, while the opposite trend is found for the hydrophilic antioxidants Trolox and ascorbic acid. The methodology to evaluate natural antioxidants must be carefully interpreted depending on whether oxidation is carried out in bulk oils or in emulsions, and what method is used to measure lipid oxidation.     

Microwave inactivation of Cyclospora cayetanensis sporulation and viability of Cryptosporidium parvum oocysts

The efficacy of microwave heating on the viability of Cryptosporidium parvum oocysts and on the sporulation of Cyclospora cayetanensis oocysts for various periods of cooking times (0, 10, 15, 20, 30, and 45 s) at 100% power was determined. Cyclospora oocysts were stored in 2.5% dichromate at 23 degrees C for 2 weeks, and sporulation rates were then determined. The 4',6-diamidino-2-phenylindole and propidium iodide vital stain and the neonate animal infectivity assay determined Cryptosporidium oocyst viability. Cryptosporidium oocysts could be completely inactivated with as little as 20 s of cooking time, whereas Cyclospora sporulation was observed up to 45 s. Two of the examined microwave ovens were more effective at reducing sporulation and viability than the third one. Because of the variability of temperature achieved by the various ovens, cooking time was not an accurate parameter for parasite inactivation. Cryptosporidium oocysts could be inactivated only when temperatures of 80 degrees C or higher were reached in the microwave ovens.     

饮用水中贾第鞭毛虫和隐孢子虫能力验证的研究

通过对贾第鞭毛虫和隐孢子虫能力进行验证,分析水中两虫回收率的影响因素。采用Enivrochek~(TM)法对能力验证样品进行测定。本试验方法的回收率满足组织方的要求,可应用于水样的检测。     

Foodborne illness associated with Cryptosporidium and Giardia from livestock

Waterborne outbreaks caused by Cryptosporidium and Giardia are well documented, while the public health implications for foodborne illness from these parasites have not been adequately considered. Cryptosporidium and Giardia are common in domestic livestock, where young animals can have a high prevalence of infection, shedding large numbers of oocysts and cysts. Molecular epidemiological studies have advanced our knowledge on the distribution of Cryptosporidium and Giardia species and genotypes in specific livestock. This has enabled better source tracking of contaminated foods. Livestock generate large volumes of fecal waste, which can contaminate the environment with (oo)cysts. Evidence suggests that livestock, particularly cattle, play a significant role in food contamination, leading to outbreaks of cryptosporidiosis. However, foodborne giardiasis seems to originate primarily from anthroponotic sources. Foodborne cryptosporidiosis and giardiasis are underreported because of the limited knowledge of the zoonotic potential and public health implications. Methods more sensitive and cheaper are needed to detect the often-low numbers of (oo)cysts in contaminated food and water. As the environmental burden of Cryptosporidium oocysts and Giardia cysts from livestock waste increases with the projected increase in animal agriculture, public health is further compromised. Contamination of food by livestock feces containing Cryptosporidium oocysts and Giardia cysts could occur via routes that span the entire food production continuum. Intervention strategies aimed at preventing food contamination with Cryptosporidium and Giardia will require an integrated approach based on knowledge of the potential points of entry for these parasites into the food chain. This review examines the potential for foodborne illness from Cryptosporidium and Giardia from livestock sources and discusses possible mechanisms for prevention and control.     

Pulsed electric field processing of foods: a review.

Use of pulsed electric fields (PEFs) for inactivation of microorganisms is one of the more promising nonthermal processing methods. Inactivation of microorganisms exposed to high-voltage PEFs is related to the electromechanical instability of the cell membrane. Electric field strength and treatment time are the two most important factors involved in PEF processing. Encouraging results are reported at the laboratory level, but scaling up to the industrial level escalates the cost of the command charging power supply and of the high-speed electrical switch. In this paper, we critically review the results of earlier experimental studies on PEFs and we suggest the future work that is required in this field. Inactivation tests in viscous foods and in liquid food containing particulates must be conducted. A successful continuous PEF processing system for industrial applications has yet to be designed. The high initial cost of setting up the PEF processing system is the major obstacle confronting those who would encourage the system's industrial application. Innovative developments in high-voltage pulse technology will reduce the cost of pulse generation and will make PEF processing competitive with thermal-processing methods.     

Determination of vitamin D in foods: a review.

Determining vitamin D content in foods is difficult because in natural foods of highest vitamin D activity, and even in vitamin D-fortified foods, only small quantities are present, and many other compounds are extracted along with vitamin D that cause difficulties in purifying the extract or in the spectrophotometry or colorimetry that follows. Several physicochemical methods--such as spectrophotometric, colorimetric, thin-layer chromatographic, adsorption, partition, gas-liquid, and high-performance column chromatographic--have been tried for assay foods for vitamin D, but none of them have been accepted for official or routine use; they are time consuming and expensive, or lack the required sensitivity, precision, or accuracy. Curative biological assays, based on degree of healing of a leg bone of rats previously made rachitic, is the generally accepted method to determine vitamin D content of foods. However, that method also requires too much time and is expensive. The recently developed high-performance liquid chromatographic method may offer the most for establishing a satisfactory physicochemical method for determining vitamin D in foods. Many of the difficulties and problems in assaying foods for vitamin D are discussed.     

Weaning foods and their impact on child-feeding practices among low-income Nigerian mothers

BACKGROUND: Many children in rural communities of developing countries die of nutrition-related causes due to lack of nutrition education and low purchasing power of the families, which result in low-quality weaning foods and poor feeding practices. OBJECTIVE: To evaluate the nutritional composition of local weaning foods and their impact on child feeding practices among low-income Nigerian mothers. METHODS: A cross-sectional survey was conducted between March and June 2005 among 294 randomly selected pairs of nursing mothers and their children who attended the postnatal clinic of State Specialist Hospital and Comprehensive Health Centers in Akure community, Ondo State, Nigeria. A structured, self-or interviewer-administered questionnaire was used to collect information on infant demographic characteristics, feeding, and socioeconomic characteristics of the parents. The children's weights were recorded, and samples of the weaning foods were analyzed. RESULTS: The mothers' ages ranged from 22 to 37 years, and the children's from one to 12 months. Among the parents, two-fifths of the respondents worked as drivers, mechanics, carpenters, and the like, while the remaining respondents were civil servants, health professionals, teachers, merchants, and housewives. The educational attainment of the parents ranged from no formal education (1.4%) to higher education (46%); 13% had completed primary school, and 39.6% had completed secondary school. The average monthly family income was between 3,500 and 30,000 naira (US dollar 23.3-dollar 200). Among the children, 58.3% were of normal weight, 41.1% were mildly underweight, 0.3% moderately underweight, and 0.3% severely underweight; 23.1% were exclusively breastfed, 9.5% received breastmilk and traditional medicinal herbs, 15.6% received breastmilk and commercial weaning food, 7.4% received commercial weaning food only, 14.8% received local weaning foods only, 24.1% received local weaning foods plus breastmilk, and 5.8% received the family diet. CONCLUSIONS: We found that a high proportion of the nursing mothers used local ingredients to formulate weaning foods for their babies. The nutritional compositions of these foods is of high quality and are suitable as weaning foods, particularly for infants of low-income parents who do not have access to commercial weaning foods.     

Use of a common laboratory glassware detergent improves recovery of Cryptosporidium parvum and Cyclospora cayetanensis from lettuce, herbs and raspberries

The success of any protocol designed to detect parasitic protozoa on produce must begin with an efficient initial wash step. Cryptosporidium parvum and Cyclospora cayetanensis oocysts were seeded onto herbs, lettuces and raspberries, eluted with one of four wash solutions and the recovered number of oocysts determined via fluorescent microscopy. Recovery rates for fluorescein thiosemicarbazide labeled C. parvum oocysts seeded onto spinach and raspberries and washed with de-ionized water were 38.4 ± 10.1% and 34.9 ± 6.2%, respectively. Two alternative wash solutions viz. 1M glycine, pH 5.5 and a detachment solution were tested also using labeled C. parvum seeded spinach and raspberries. No statistically significant difference was noted in the recovery rates. However, a wash solution containing 0.1% Alconox, a laboratory glassware detergent, resulted in a significant improvement in oocyst recovery. 72.6 ± 6.6% C. parvum oocysts were recovered from basil when washed with 0.1% Alconox compared to 47.9 ± 5.8% using detachment solution. Also, C. cayetanensis oocysts were seeded onto lettuces, herbs and raspberries and the recovery using de-ionized water were compared to 0.1% Alconox wash: basil 17.5 ± 5.0% to 76.1 ± 14.0%, lollo rosso lettuce 38.3 ± 5.5% to 72.5 ± 8.1%, Tango leaf lettuce 45.9 ± 5.4% to 71.1 ± 7.8% and spring mix (mesclun) 39.8 ± 0.7% to 80.2 ± 11.3%, respectively. These results suggest that the use of Alconox in a wash solution significantly improves recovery resulting in the detection of these parasitic protozoa on high risk foods.     

Structural and mechanical characteristics of bread and their impact on oral processing: a review

Oral processing has become an important area of research in sensory and nutrition studies. Mastication process not only determines the dynamics of flavour release and texture perception but also affects the bioavailability of nutrients. Oral processing of bread is of particular interest because of the need to reduce its glycaemic potential while keeping its desired soft and aerated texture. Bread structure determines its mechanical strength and deformation behaviour which in turn decides people's texture perception and swallowing thresholds. The strong interconnection between food structure and its resistance to breakdown is the rationale behind designing bread to control bread digestion, starting from the oral phase. The present review summarises the characterisation and formation of bread structure, its interlink with bread mechanical behaviour and destruction during human oral processing. Future research should further elucidate the structure–mechanics–digestion interlink by implementing relevant mechanical analyses and micromechanical modelling.     

Sodium reduction technologies applied to bread products and their impact on sensory properties: a review

Chronic overconsumption of sodium has led to its designation as a nutrient of public health concern. While the current adequate intake (AI) of sodium is set at 1.5 g per day, the average daily intake for Americans ages one and up is currently above 3.5 g, leading to an increased risk of health conditions such as hypertension and cardiovascular disease (CVD). Due to the prevalence of daily bread consumption and the moderately high sodium content that accompanies it, bread has become a major contributor to dietary sodium intake. Still people seem to associate foods higher in sodium content, such as processed meats and frozen foods, as the main way to limit sodium consumption, and therefore, overlook the contribution made by regularly consuming bread. This review focuses on recent research detailing methods that are being implemented in attempts to reduce the sodium content of bread products. Included literature examined the perspective of sensory feasibility and on identifying gaps in knowledge surrounding viable strategies for producing reduced-sodium breads. Sodium reduction technologies discussed include methods in the areas of salt removal, physical modification, salt replacement and flavour modification.     

Detection of Cryptosporidium and Giardia in molluscan shellfish by multiplexed nested-PCR

A multiplexed nested-PCR procedure (ABC-PCR) previously developed to detect Cryptosporidium spp. and Giardia duodenalis assemblages A and B in whole human faeces was applied to DNA extracted from filter-feeding molluscs. Species of Cryptosporidium and G. duodenalis were identified by restriction fragment analysis of the PCR products and by DNA sequencing. The extraction and ABC-PCR procedures were shown to be suitable for application to shellfish by amplification of specific target sequences using DNA from Cryptosporidium parvum genotype 2 and G. duodenalis assemblages A and B which were spiked into DNA extracted from mussels. Using 49 molluscan shellfish specimens (18 clam, 22 mussel and 9 oyster samples) from Spain, cryptosporidial oocysts were detected in 56% by immunofluorescence microscopy, and in 44% by ABC-PCR. For detection of Cryptosporidium, there was a significant association, but not total agreement, between the results of microscopy and PCR. G. duodenalis assemblage B was detected from one oyster sample by PCR. Amongst 38 specimens (20 mussel and 18 cockle samples) collected in the UK and tested by the ABC-PCR, G. duodenalis was not detected, and Cryptosporidium was detected in 11% of the samples. Overall, the 26 samples where Cryptosporidium was detected, C. hominis/C. parvum genotype 1 was detected in 1, C. parvum genotype 2 in 22, and the remaining three samples contained either sequences similar to C. parvum genotype 2 or heterogeneous mixtures of Cryptosporidium species. There was no significant association between the level of Escherichia coli detected by conventional microbiological methods and the presence of Cryptosporidium detected by ABC-PCR.     

Protein oxidation in muscle foods: a review

Protein oxidation in living tissues is known to play an essential role in the pathogenesis of relevant degenerative diseases, whereas the occurrence and impact of protein oxidation (Pox) in food systems have been ignored for decades. Currently, the increasing interest among food scientists in this topic has led to highlight the influence that Pox may have on meat quality and human nutrition. Recent studies have contributed to solid scientific knowledge regarding basic oxidation mechanisms, and in advanced methodologies to accurately assess Pox in food systems. Some of these studies have provided insight into the reactions involved in the oxidative modifications undergone by muscle proteins. Moreover, a variety of products derived from oxidized muscle proteins, including cross-links and carbonyls, have been identified. The impact of oxidation on protein functionality and on specific meat quality traits has also been addressed. Some other recent studies have shed light on the complex interaction mechanisms between myofibrillar proteins and certain redox-active compounds such as tocopherols and phenolic compounds. This paper is devoted to review the most relevant findings on the occurrence and consequences of Pox in muscle foods. The efficiency of different anti-oxidant strategies against the oxidation of muscle proteins is also reported.     

Transport of MS2 phage, Escherichia coli, Clostridium perfringens, Cryptosporidium parvum, and Giardia intestinalis in a gravel and a sandy soil

To define protection zones around groundwater abstraction wells and safe setback distances for artificial recharge systems in watertreatment, quantitative information is needed about the removal of microorganisms during soil passage. Column experiments were conducted using natural soil and water from an infiltration site with fine sandy soil and a river bank infiltration site with gravel soil. The removal of phages, bacteria, bacterial spores, and protozoan (oo)-cysts was determined at two velocities and compared with field data from the same sites. The microbial elimination rate (MER) in both soils was generally >2 log, but MER in the gravel soil was higher than that in the fine sandy soil. This was attributed to enhanced attachment, related to higher metal-hydroxides content. From the high sticking efficiencies (>1) and the low influence of flow rate on MER it was deduced that straining played a significant role in the removal of Escherichia coli and Cryptosporidium parvum oocysts in the gravel soil. Lower removal of oocysts than the 4-5 times smaller E. coli and spores in the fine sand indicates that the contribution of straining is variable and needs further attention in transport models. Thus, simple extrapolation of grain size and particle size to the extent of microbial transport underground is inappropriate. Finally, the low MER of indigenous E. coli and Clostridium perfringens observed in the soil columns as well as under field conditions and the second breakthrough peak found for Cryptosporidium and spores in the fine sandy soil upon a change in the feedwater pH indicate a significant role of detachment and retardation to microbial transport and the difficulty of extrapolation of quantitative column test results to field conditions.     

Baby foods: formulations and interactions (a review)

Infant foods have a special place among food products mainly because of nutritional aspects and preparations methods. A great increase of baby foods incomes is predicted in near future. Formulation, handling, and storage of baby foods are important to keep nutritional quality and physicochemical properties of these foods. During storage some reactions and interactions occur which change physicochemical and nutritional properties of baby foods. Lactose crystallization, Maillard reaction, oxidation, and interactions between micronutrients and other components are the most important aspect of preparation and storage of baby foods. These reactions and interactions influence physical properties such as flowability of powder, solubility, and other functional properties. Controlling of storage conditions such as temperature and moisture content and oxygen quantity in headspace of product is required to keep product quality. In this paper the composition and interactions of baby foods between major components and their effect on nutritional quality of baby foods are explained.