Commercial Food Products Research Articles

Simultaneous determination of riboflavin and pyridoxine by UHPLC/LC–MS in UK commercial infant meal food products

An assay for the simultaneous quantitative determination of riboflavin and pyridoxine in eight different complementary infant meal products has been developed in order to (1) estimate the daily intake of these vitamins from commercial infant food consumption, and (2) ascertain their nutritional suitability relative to dietary guidelines for the 6–9months age group. The method involves mild hydrolysis of the foods, an extraction of the supernatant by centrifugation followed by quantitative determination using ultra-high performance liquid chromatography. Separation of the two water soluble vitamins is achieved within one minute and the resultant sample is also LC–MS compatible. Despite wide individual differences between brands (p=6.5e-12), no significant differences were observed in the level of pyridoxine between the meat and vegetable-based varieties (p=0.7) per 100g of commercial infant food. Riboflavin was not detected in any of the samples where the detection limit was below 0.07μg/mL. In terms of the Reference Nutrient Intake (RNI) of pyridoxine for 6–9months old infants, the complementary infant meal products analysed herein provided less than 15% of the RNI values with mean (SD) values of 12.87 (±4.46)% and 13.88 (±4.97)% for the meat- and vegetable-based recipes, respectively. The estimated total daily intake of riboflavin and pyridoxine from the consumption of commercial complementary food was found to be satisfactory and in accordance with the Dietary Reference Values (DRVs). The intake of both riboflavin and pyridoxine was estimated to be mainly derived from the consumption of formula milk which could be a cause of concern if the quality of an infant’s milk diet is compromised by an inadequate or lack of supplemented milk intake. The results of this study suggest that the selected commercial complementary infant foods in the UK market may not contain the minimum levels of riboflavin and pyridoxine required for the labelling declaration of the micronutrient content of such products as recommended by Commission Directive 2006/125/EC.

Physicochemical characteristics of mixed colloidal dispersions: Models for foods containing fat and starch

Mixed colloidal dispersions, consisting of starch granules and lipid droplets, were used as model systems to represent commercial food products, such as sauces, desserts, and soups. Colloidal dispersions were prepared by mixing unheated modified starch (3.5 or 5.0 wt%) and lipid droplets (2.5, 5.0 or 8.0 wt% oil) together and then heating (90 °C for 5 min) to promote starch gelatinization. The lipid droplets were stabilized by a food-grade surfactant consisting of a mixture of diacetyl tartaric acid ester of mono-diglycerides (DATEM) and mono-diglycerides. The influence of thermal processing and composition (starch, lipid, surfactant content) on the particle size, microstructure, lightness, and shear viscosity of the model sauces was examined. There was a pronounced increase in shear viscosity upon heating, which was attributed to the swelling of the starch granules leading to a close-packed particle suspension. The shear viscosity and lightness of the colloidal dispersions increased with increasing starch and fat content, with fat droplets dominating lightness and starch granules dominating viscosity. The amount of surfactant present also influenced the rheology of the mixed colloidal dispersions, which was attributed to its ability to modify starch granule interactions. Overall, these results have important implications for designing high quality emulsion-based food products, such as soups, sauces, desserts, and beverages.

Detection of Gliadin in Foods Using a Quartz Crystal Microbalance Biosensor That Incorporates Gold Nanoparticles

This work develops a label-free gliadin immunosensor that is based on changes in the frequency of a quartz crystal microbalance (QCM) chip. A higher sensitivity was obtained by applying 25 nm gold nanoparticles (AuNPs) to the surface of a bare QCM electrode. Subsequently, chicken anti-gliadin antibodies (IgY) were immobilized directly on the AuNP-modified surface by cross-linking amine groups in IgY with glutaraldehyde. Experimental results revealed that the change in frequency exhibited when 2 ppm gliadin was bound to the AuNP-modified electrode was 35 Hz (48%) greater than that of the bare gold electrode. The linear dynamic range in 60% ethanol was from 1 × 10(1) to 2 × 10(5) ppb gliadin, and the calculated limit of detection (LOD) was 8 ppb. The entire detection process was completed in 40 min and was highly repeatable. Additionally, the AuNP-modified QCM system generated results in the detection of gliadin in 10 commercial food products that were consistent with those obtained using an AOAC-approved gliadin kit. In conclusion, the QCM platform provides a potential alternative means of ensuring that people with wheat allergies and celiac patients have access to gliadin-free food.

Analysis on the results of food safety risk monitoring in Haizhu district of Guangzhou

Objective To investigate and analyze the level and trend of food pollution,and evaluate the situation of food safety.Method Different kinds of food were taken randomly from various supermarkets and agricultural products markets in Haizhu district,and chemical contaminants and foodborne pathogens were analyzed.Results During 2009 and 2011,total 438 samples were collected and tested.The results indicated that total eligible rate was 73.05％.The detection rate of vibrio parahaemolyticus in the seafood was 27.78％.The detection rate of salmonella in meat was 4.28％.The pollution of coliform group in cooked meat and salads was serious,with the detection rate of 25.67％.The heavy metal lead and cadmium in meat,tea,sea fishes and freshwater fishes exceeded the standard,with the superstandard rate at 2.67％ and 5.43％,respectively.The formaldehyde pollution in waterishlogged food products was also serious.Conclusion There is security risk in the commercial food products in Haizhu district.To ensure the food safety,the monitoring managements to different kinds of food need to be strengthened. Key words: Food; Safety risk ; Monitoring; Analysis

STATISTICAL ANALYSIS OF DATA FROM THE “SCORE AND RANK” PROCEDURE IN PREFERENCE STUDIES WITH CHILDREN

ABSTRACTThe elicitation of preferences among children is a key to the successful development of products designed for children. Among the several hedonic methodologies adapted for children aged between 6 and 10, the “score and rank” procedure introduced by L. L. Birch et al. was selected and tested. This procedure comprises two steps: hedonic categorization followed by ranking within each hedonic category. A new strategy of data analysis generated from this procedure of evaluation is discussed and illustrated on the basis of case studies with primary school children with whom close variants of commercial food products were tested.PRACTICAL APPLICATIONSThe data processing strategy suggested for the “score and rank” procedure yields scores associated with the products being evaluated. In comparison with the usual procedure of data analysis that is based on ranks, the new strategy of analysis does not overestimate the differences in likings between the products and the number of consumers clusters.

Fast food and junk food: an encyclopedia of what we love to eat

This fascinating and revealing work examines the incredible power of junk food and fast food-how nostalgic we are about them, the influence of the companies that manufacture or sell them, and their alarming effect on our country's state of health. In the last half century, junk food and fast food have come to play an extremely important role in American economic, historical, cultural, and social life. Today, they have a major influence on what Americans eat-and how healthy we are (or aren't). Fast Food and Junk Food: An Encyclopedia of What We Love to Eat tells the intriguing, fun, and incredible stories behind the successes of these commercial food products and documents the numerous health-related, environmental, cultural, and politico-economic issues associated with them. With more than 700 alphabetically arranged entries, this two-volume encyclopedia contains enough listings to allow readers to research a wide range of fascinating topics. The author treats the massive amount of subject material within this reference title in a fair and balanced manner. A secondary focus of this encyclopedia is to chart the spread of some American fast food chains and commercially produced junk foods internationally. More than 700 A-Z entries on fast food, comfort food, and junk food, ranging from breakfast cereals to burgers and fries to snack chips and candy A chronology of the significant events in the history of junk food and fast food A bibliography containing more than 200 entries with citations to books, articles, and websites A glossary of important terms used in the encyclopedia A Resource Guide containing important DVDs, films and videos, and television series

Pathogenesis and Treatment of Hepatitis E Virus Infection

Hepatitis E has been considered to be a travel-associated, acute, self-limiting liver disease that causes fulminant hepatic failure in specific high-risk groups only. However, hepatitis E virus (HEV) infection can also be acquired in industrialized countries-HEV genotype 3 infection is a zoonosis, with pigs and rodents serving as animal reservoirs. In recent years, cases of chronic HEV infection that were associated with progressive liver disease have been described in several cohorts of immunocompromised individuals, including recipients of organ transplants. The topic of hepatitis E is therefore re-emerging and has raised the following important questions: what is the risk for HEV infection in Western countries (eg, from eating uncooked meat)? How frequently does chronic hepatitis E develop among human immunodeficiency virus-infected patients and recipients of organ transplants? What are the treatment options? What is the current status of vaccine development? What do we know about the pathogenesis of HEV infection, and why does it have a more severe course in pregnant women? This review summarizes the current knowledge on the pathogenesis and treatment of HEV infection.

Effects of sensory labels on taste acceptance of commercial food products

This study was performed to examine effects of sensory labels on taste acceptance of commercial food products. Specifically, the effects of two factors of sensory labels, expected sensory quality (ESQ) and similarity between ESQ and perceived sensory quality (PSQ), on taste acceptance were examined. The levels of ESQ, similarity between ESQ and PSQ, blind taste acceptability (BTA), and informed taste acceptability (ITA) of 12 commercial food products given two different items of information were analyzed. Most of the presented labels were comprised of product information related to sensory properties including taste, flavor, texture, and appearance. Twelve of the labels were selected from the front side of the 12 products’ packages, respectively, and the other 12 labels were made to provide more detailed sensory information of each product. There was a significant positive correlation between the ITA and the similarity of ESQ and PSQ. When the similarity of ESQ and PSQ was higher than the ESQ, the ITA was significantly higher than BTA. A quadratic equation explaining the relationship between the [similarity of ESQ and PSQ/ESQ] and [ITA/BTA] was suggested, with R2 of 0.993. The equation could be used for determining the level of similarity between ESQ and PSQ/ESQ to increase ITA over BTA by a certain level.

DNA Barcoding of Yeasts from Selected Bulgarian Food Products

ABSTRACTStudies on biodiversity of yeasts in Bulgarian food ecosystems are scarce. In present article 14 yeast strains were isolated from various commercial Bulgarian food products and characterized by DNA barcoding analysis. The analysis has shown occurrence in food products various yeasts from the following genera- Saccharomyces, Kazachstania, Kluyveromyces, Pichia, Isatchenkia, Candida and Rhodotorula.

Advances in Irrigation: Select Works From the 2010 Decennial Irrigation Symposium

This paper is an introduction to the Advances in Irrigation Special Collection in this issue of Transactions ASABE and the next issue of Applied Engineering in Agriculture of 14 papers selected from 88 papers and presentations at the ASABE 5th Decennial National Irrigation Symposium, December 2010, in Phoenix, Arizona. This symposium followed the objectives of the previous four decennial events to provide a forum to assess progress of research endeavors to advance the effectiveness of irrigation practices during the past 10 years, leading to further research priorities that respond to future challenges. The papers in this Collection address a wide range of topics grouped into broad categories: microirrigation, center pivot irrigation, crop water use for improved irrigation management, and smart irrigation controllers for landscape irrigation. While these papers are not inclusive of all irrigation work since the last decennial symposium, they do provide a snapshot of work considered important by researchers, funding agencies and other stakeholders. Many aspects of irrigation have changed since the first symposium in 1970. Although microirrigation is a small proportion of irrigated acreage, it will continue to increase in highly technical commercial food and fiber production as well as in subsistence farming. Center pivot irrigation systems have been an important tool to deliver water more efficiently in diverse settings. Advanced telemetry and control systems, developed during the past 10 years, are now common options for center pivots, but challenges remain to integrate those hardware developments into crop management practices. Possibilities are emerging for adding monitoring devices to center pivots to match crop water needs with water delivery. Energy balance models continue to be refined as tools to estimate crop water use from both ground and satellite based data. Evapotranspiration estimates are evolving from single location weather stations to whole-field or regional scopes. Finally, “smart” irrigation controllers have coupled evapotranspiration estimation or soil-water sensing with automated irrigation system water delivery. These controllers can increase the precision of irrigation to match crop or landscape water needs. Irrigation will continue to be an important practice for producing the world’s food. The irrigation research and education professions will need to respond to food production challenges with even more refined irrigation systems and water management in the next 10 years. However, research investment in irrigation continues to decline when important issues exist, such as: maintaining agricultural profitability with declining water supplies, integrating sensor-based information for real-time autonomous or semi-autonomous management, competition for limited water supplies between agriculture and other sectors, increasing energy cost, environmental impacts of irrigation, and use of alternative water sources (i.e., lower quality) for irrigation.

ASSESSING THE SHAPES AND SPEECH SOUNDS THAT CONSUMERS ASSOCIATE WITH DIFFERENT KINDS OF CHOCOLATE

ABSTRACTReliable crossmodal correspondences have been demonstrated between dark and mint chocolates with angular shapes and sharper‐sounding speech sounds on one hand, and between milk chocolate with organic shapes and rounder‐sounding speech sounds on the other. In the present study, a panel of consumers was presented with four different chocolates: two mints (solid and fondant), one dark and one milk. They either tasted (Experiment 1) or simply imagined tasting (Experiment 2) the chocolates and indicated whether the perceived flavor matched one or other of the items (nonsense words or simple outline shapes) anchoring various line scales by marking a point along each scale. Dark and solid mint chocolates were more angular‐shaped and associated with sharp meaningless speech sounds (e.g., “tuki” and “takete”). Mint fondant, by contrast, was considered less angular and more pleasant than dark or solid mints, while milk chocolate was more pleasant and strongly associated with organic shapes and rounded speech sounds (e.g., “lula” and “maluma”). These results corroborate and build upon recent findings concerning sound symbolism in the taste and flavor domain by highlighting the fact that oral‐somatosensory textural cues play an important role in determining the crossmodal correspondences that regular consumers have for foodstuffs such as chocolate.PRACTICAL APPLICATIONSWhether taste or texture, or some combination of the two sensory attributes, is responsible for the systematic associations between various chocolates and certain angular/sharp or organic shapes and speech sounds remains unclear. The results of the present study demonstrate that both attributes play an important role in determining consumers' crossmodal correspondences. Thus, when conducting research on various food qualities, these two factors should be carefully considered and/or systematically controlled. Additionally, the fact that these results held across different testing protocols (laboratory‐based vs. online) confirms the potential utility of internet‐based food testing for quantitatively and, importantly, qualitatively valuable/sound data collection (at least for foods that consumers are familiar with). The results of experiments such as those reported here can, in the future, be used to provide insights regarding the speech sounds and abstract imagery that should be associated with specific oral‐somatosensory and taste/flavor attributes in commercial food products. Such results may be used to develop abstract imagery for product packaging and/or brand names/logos that more effectively capture the shape/sound symbolic properties of the food concerned.

Detecting nanoparticulate silver using single‐particle inductively coupled plasma–mass spectrometry

The environmental prevalence of engineered nanomaterials, particularly nanoparticulate silver (AgNP), is expected to increase substantially. The ubiquitous use of commercial products containing AgNP may result in their release to the environment, and the potential for ecological effects is unknown. Detecting engineered nanomaterials is one of the greatest challenges in quantifying their risks. Thus, it is imperative to develop techniques capable of measuring and characterizing exposures, while dealing with the innate difficulties of nanomaterial detection in environmental samples, such as low-engineered nanomaterial concentrations, aggregation, and complex matrices. Here the authors demonstrate the use of inductively coupled plasma-mass spectrometry, operated in a single-particle counting mode (SP-ICP-MS), to detect and quantify AgNP. In the present study, two AgNP products were measured by SP-ICP-MS, including one of precisely manufactured size and shape, as well as a commercial AgNP-containing health food product. Serial dilutions, filtration, and acidification were applied to confirm that the method detected particles. Differentiation of dissolved and particulate silver (Ag) is a feature of the technique. Analysis of two wastewater samples demonstrated the applicability of SP-ICP-MS at nanograms per liter Ag concentrations. In this pilot study, AgNP was found at 100 to 200 ng/L in the presence of 50 to 500 ng/L dissolved Ag. The method provides the analytical capability to monitor Ag and other metal and metal oxide nanoparticles in fate, transport, stability, and toxicity studies using a commonly available laboratory instrument. Rapid throughput and element specificity are additional benefits of SP-ICP-MS as a measurement tool for metal and metal oxide engineered nanoparticles.

Consumer Acceptance of Ginseng Food Products

Ginseng has been utilized less in food products than in dietary supplements in the United States. Sensory acceptance of ginseng food products by U.S. consumers has not been reported. The objectives of this study were to: (1) determine the sensory acceptance of commercial ginseng food products and (2) assess influence of the addition of sweeteners to ginseng tea and ginseng extract to chocolate on consumer acceptance. Total of 126 consumers participated in 3 sessions for (1) 7 commercial red ginseng food products, (2) 10 ginseng teas varying in levels of sugar or honey, and (3) 10 ginseng milk or dark chocolates varying in levels of ginseng extract. Ginseng candy with vitamin C and ginseng crunchy white chocolate were the most highly accepted, while sliced ginseng root product was the least accepted among the seven commercial products. Sensory acceptance increased in proportion to the content of sugar and honey in ginseng tea, whereas acceptance decreased with increasing content of ginseng extract in milk and dark chocolates. Findings demonstrate that ginseng food product types with which consumers have been already familiar, such as candy and chocolate, will have potential for success in the U.S. market. Chocolate could be suggested as a food matrix into which ginseng can be incorporated, as containing more bioactive compounds than ginseng tea at a similar acceptance level. Future research may include a descriptive analysis with ginseng-based products to identify the key drivers of liking and disliking for successful new product development.

Influence of interfacial composition on oxidative stability of oil-in-water emulsions stabilized by biopolymer emulsifiers

The objective of this research was to evaluate the influence of storage pH (3 and 7) and biopolymer emulsifier type (Whey protein isolate (WPI), Modified starch (MS) and Gum arabic (GA)) on the physical and oxidative stability of rice bran oil-in-water emulsions. All three emulsifiers formed small emulsion droplets (d32<0.5μm) when used at sufficiently high levels: 0.45%, 1% and 10% for WPI, MS and GA, respectively. The droplets were relatively stable to droplet growth throughout storage (d32<0.6μm after 20days), although there was some evidence of droplet aggregation particularly in the MS-stabilized emulsions. The electrical charge on the biopolymer-coated lipid droplets depended on pH and biopolymer type: −13 and −27mV at pH 3 and 7 for GA; −2 and −3mV at pH 3 and 7 for MS; +37 and −38mV at pH 3 and 7 for WPI. The oxidative stability of the emulsions was monitored by measuring peroxide (primary products) and hexanal (secondary products) formation during storage at 37°C, for up to 20days, in the presence of a pro-oxidant (iron/EDTA). Rice bran oil emulsions containing MS- and WPI-coated lipid droplets were relatively stable to lipid oxidation, but those containing GA-coated droplets were highly unstable to oxidation at both pH 3 and 7. The results are interpreted in terms of the impact of the electrical characteristics of the biopolymers on the ability of cationic iron ions to interact with emulsified lipids. These results have important implications for utilizing rice bran oil, and other oxidatively unstable oils, in commercial food and beverage products.

Development and validation of a novel real-time PCR method for the detection of celery (Apium graveolens) in food

The paper presents a novel real-time PCR method allowing the detection of traces of celery (Apium graveolens) in complex food matrices. The method is based on the amplification of a sequence of the gene coding for the Apium graveolens NADPH-dependent mannose-6-phosphate reductase. It allows the detection of three commonly used celery varieties, celery roots (Apium graveolens var. rapaceum), celery stalks (Apium graveolens var. dulce) and leaf celery (Apium graveolens var. secalinum) and does not show any cross-reactivity with 64 biological species, including ten members of the Apiaceae family. The limit of detection, determined by analysing serially diluted celery extracts, is 10pg celery DNA for all three celery varieties. In spiked model sausages, the LOD is 0.005% celery. The real-time PCR method was applied to 26 commercial food products. Celery DNA was found in one out of ten samples without any information about the presence of celery.

Application of species-specific polymerase chain reaction assays to verify the labeling of quail ( Coturnix coturnix), pheasant ( Phasianus colchicus) and ostrich ( Struthio camelus) in pet foods

Species-specific polymerase chain reaction (PCR) assays have been applied to verify the labeling of pet foods containing quail, pheasant, and ostrich. The method combines the use of quail, pheasant, ostrich, chicken, duck, pig and fish specific primers that amplify small fragments (amplicons <200 base pairs) of the mitochondrial 12S rRNA gene and a positive control primer pair that amplifies a 141 bp fragment of the nuclear 18S rRNA gene from eukaryotic DNA. The applicability of the assay was tested through the analysis of 100 commercial dog and cat food products. The reported PCR technique successfully detected the presence of the target species in 88 of the analyzed samples. However, the target species was not detected in 12 samples indicating a possible fraud in the labeling of these products. The results obtained suggest that the reported PCR method may represent a suitable tool for the detection of pet food mislabeling.

Sensory quality index (SQI) for commercial food products

The level of potential deterioration in sensory qualities during distribution of processed commercial food products was measured. A method to set up a distribution sensory quality hurdle was suggested to determine the level of deterioration of sensory quality according to consumer responses. The sensory quality index (SQI), which is the ratio of the overall acceptability of a product at the end of its shelf life to that at the beginning of its shelf life, showed a strong positive correlation with consumer preference (%) across a broad range of products. The complexity caused by the “no preference” option in the preference test was decreased by using the SQI because it allows equal scores when comparing samples in acceptability tests. Also, a strong positive correlation between the SQI and the difference of acceptability scores from the beginning to the end of the shelf life support the reliability of the SQI, which is a ratio estimated by dividing the measured scores with an interval scale.

Adulterations in Basmati rice detected quantitatively by combined use of microsatellite and fragrance typing with High Resolution Melting (HRM) analysis

The aim of this work was to setup a DNA based method coupled with High Resolution Melting (HRM) analysis for rice products traceability using five different microsatellite markers to genotyping Basmati and non-Basmati varieties. We also exploit the obtained information to detect the presence of Basmati varieties in commercial rice products. Additionally we used the 8bp deletion in badh2 gene in combination with HRM to both DNA-typing of the Basmati and non-Basmati varieties and to quantitate accurately adulteration of Basmati rice products with non-Basmati rice products. HRM proved to be a very sensitive tool to genotype rice varieties and detect admixtures as well as able to detect a ratio of 1:100 of non-fragrance in fragrance rice. In conclusion HRM analysis can be a higher resolution, cost effective, alternative method compared to other techniques that could be extended to quantify adulterations in rice varieties and commercial rice food products.

Differential Detection of Shrimp and Crab for Food Labeling Using Polymerase Chain Reaction

Shrimp and crab are well-known as allergenic ingredients. According to Japanese food allergy labeling regulations, shrimp species (including prawns, crayfishes, and lobsters) and crab species must be differentially declared when ≥10 ppm (total protein) of an allergenic ingredient is present. However, the commercial ELISA tests for the detection of crustacean proteins cannot differentiate between shrimp and crab. Therefore, two methods were developed to discriminate shrimp and crab: a shrimp-PCR method with postamplification digestion and a crab-PCR method that specifically amplifies a fragment of the 16S rRNA gene. The sensitivity and specificity of both PCR methods were verified by experiments using DNA extracted from 15 shrimp species, 13 crab species, krill, mysid, mantis shrimp, other food samples (cephalopod, shellfish, and fish), incurred foods, and commercial food products. Both PCR methods could detect 5 pg of DNA extracted from target species and 50 ng of genomic DNA extracted from incurred foods containing 10 ppm (μg/g) total protein of shrimp or crab. The two PCR methods were considered to be specific enough to separately detect species belonging to shrimp and crab. Although false-positive and false-negative results were obtained from some nontarget crustacean species, the proposed PCR methods, when used in conjunction with ELISA tests, would be a useful tool for confirmation of the validity of food allergy labeling and management of processed food safety for allergic patients.

Results from raw milk microbiological tests do not predict the shelf-life performance of commercially pasteurized fluid milk

Analytical tools that accurately predict the performance of raw milk following its manufacture into commercial food products are of economic interest to the dairy industry. To evaluate the ability of currently applied raw milk microbiological tests to predict the quality of commercially pasteurized fluid milk products, samples of raw milk and 2% fat pasteurized milk were obtained from 4 New York State fluid milk processors for a 1-yr period. Raw milk samples were examined using a variety of tests commonly applied to raw milk, including somatic cell count, standard plate count, psychrotrophic bacteria count, ropy milk test, coliform count, preliminary incubation count, laboratory pasteurization count, and spore pasteurization count. Differential and selective media were used to identify groups of bacteria present in raw milk. Pasteurized milk samples were held at 6°C for 21 d and evaluated for standard plate count, coliform count, and sensory quality throughout shelf-life. Bacterial isolates from select raw and pasteurized milk tests were identified using 16S ribosomal DNA sequencing. Linear regression analysis of raw milk test results versus results reflecting pasteurized milk quality consistently showed low R2 values (<0.45); the majority of R2 values were <0.25, indicating small relationship between the results from the raw milk tests and results from tests used to evaluate pasteurized milk quality. Our findings suggest the need for new raw milk tests that measure the specific biological barriers that limit shelf-life and quality of fluid milk products.