Burnt Flavor Research Articles

The role of ultraviolet radiation in the flavor formation during drying processing of Pacific saury (Cololabis saira).

Traditional sun-drying aquatic products are popular and recognized by customers, owing to their unique flavor and long-term preservation. However, the product quality and production efficiency cannot be guaranteed. Cololabis saira is rich in unsaturated fatty acids, which are susceptible to hyperoxidation during the drying process. This study aimed to make clear the role of ultraviolet (UV) radiation in flavor formation during drying processes of Cololabis saira to develop a modern drying technology. Lipid oxidation analysis revealed that moderate hydrolytic oxidation occurred in the UV-assisted cold-air drying group due to the combined influence of UV and cold-air circulation, resulting in the thiobarbituric acid reactive substances value being higher than that of cold-air drying group but lower than the natural drying group. Hexanal, heptanal, cis-4-heptenal, octanal, nonanal, (trans,trans)-2,4-heptadienal, (trans,trans)-2,6-nonanedial, 1-octen-3-ol, heptanol, 2,3-pentanedione, 3,5-octadien-2-one and trimethylamine were identified as the characteristic flavor odor-active compounds present in all Cololabis saira samples. Yet, during the natural drying process, sunlight promoted the lipid oxidation, resulting in the highest degree of lipid oxidation among three drying methods. Light and heat promoted lipid oxidation in Cololabis saira prepared through natural drying process, leading to a large accumulation of volatile compounds, such as 3-methylbutyraldehyde, 2,3-pentanedione, 1-propanol, and 3-pentanone. Cold air circulation inhibited lipid oxidation to some extent, resulting in a blander flavor profile. More cis-4-heptenal, cis-2-heptenal, octanal and 2-ethylfuran accumulated during the UV-assisted cold-air drying process, enriching its greasy flavor and burnt flavor. UV-assisted cold-air drying could promote moderate lipid oxidation, which is beneficial for improving product flavor. To sum up, UV radiation played a crucial role in the flavor formation during the drying process of Cololabis saira. © 2024 Society of Chemical Industry.

Metabolite analysis and sensory evaluation reveal the effect of roasting on the characteristic flavor of large-leaf yellow tea.

Roasting is essential for processing large-leaf yellow tea (LYT). However, the effect of the roasting on the metabolic and sensory profiles of LYT remains unknown. Herein, the metabolomics and sensory quality of LYT at five roasting degrees were evaluated by liquid/gas chromatography mass spectrometry and quantitative descriptive analysis. A higher degree of roasting resulted in a significantly stronger crispy rice, fried rice, and smoky-burnt aroma (p<0.05), which is closely associated with heterocyclic compound accumulation (concentrations: 6.47±0.27 - 1065.00±5.58µg/g). Amino acids, catechins, flavonoid glycosides and N-ethyl-2-pyrrolidone-substituted flavan-3-ol varied with roasting degree. The enhancement of crispy-rice and burnt flavor coupled with the reduction of bitterness and astringency. Correlations analysis revealed the essential compounds responsible for roasting degree, including 2,3-diethyl-5-methylpyrazine, hexanal, isoleucine, N-ethyl-2-pyrrolidone-substituted flavan-3-ol (EPSF), and others. These findings provide a theoretical basis for improving the specific flavors of LYT.

Characterization of color, metabolites and microbial community dynamics of doubanjiang during constant temperature fermentation

This study aimed to elaborate the effect of temperature on doubanjiang fermentation. Two batches of constant-temperature groups were prepared and their physicochemical parameters, color formation, metabolites and microbial community dynamics during fermentation were determined and compared with those of natural temperature fermentation group. The results showed that fermentation at 40 °C could accelerate the accumulation of amino nitrogen, reducing sugar, amino acids, organic acids and various volatile metabolites while it was able to inhibit the growth of conditionally pathogenic bacteria, such as Klebsiella and Salmonella. However, high concentrations of total acids and biogenic amines, protrusive burnt flavor and darker color were observed in constant temperature fermentation, which were unfavorable for doubanjiang quality. Higher fermentation temperature lowered the diversity of bacterial community and favored the growth of Bacillus genus. The correlation between key microbial genera and doubanjiang quality indexes were significantly different among different temperatures. This study would deep our understanding of the roles of temperature ondoubanjiangfermentation.

Profiling the Major Aroma-Active Compounds of Microwave-Dried Jujube Slices through Molecular Sensory Science Approaches.

To discriminate the aroma-active compounds in dried jujube slices through microwave-dried treatments and understand their sensory attributes, odor activity value (OAV) and detection frequency analysis (DFA) combined with sensory analysis and analyzed through partial least squares regression analysis (PLSR) were used collaboratively. A total of 21 major aromatic active compounds were identified, among which 4-hexanolide, 4-cyclopentene-1,3-dione, 5-methyl-2(5H)-furanone, 4-hydroxy-2,5-dimethyl-3(2H)furanone, 3,5-dihydroxy-2-methyl-4-pyrone were first confirmed as aromatic compounds of jujube. Sensory evaluation revealed that the major characteristic aromas of dried jujube slices were caramel flavor, roasted sweet flavor, and bitter and burnt flavors. The PLSR results showed that certain compounds were related to specific taste attributes. 2,3-butanedione and acetoin had a significant positive correlation with the roasted sweet attribute. On the other hand, γ-butyrolactone, 4-cyclopentene-1,3-dione, and 4-hydroxy-2,5-dimethyl-3(2H)furanone had a significant positive impact on the caramel attributes. For the bitter attribute, 2-acetylfuran and 5-methyl-2(5H)-furanone were positively correlated. Regarding the burnt flavor, 5-methyl-2-furancarboxaldehyde and 3,5-dihydroxy-2-methyl-4-pyrone were the most influential odor-active compounds. Finally, 2-furanmethanol and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one were identified as the primary sources of the burnt and bitter flavors. Importantly, this work could provide a theoretical basis for aroma control during dried jujube slices processing.

Application of tea polyphenols as additives in brown fermented milk: Potential analysis of mitigating Maillard reaction products

Brown fermented milk (BFM) is favored by consumers in the dairy market for its unique burnt flavor and brown color. However, Maillard reaction products (MRP) from high-temperature baking are also noteworthy. In this study, tea polyphenols (TP) were initially developed as potential inhibitors of MRP formation in BFM. The results showed that the flavor profile of BFM did not change after adding 0.08% (wt/wt) of TP, and its inhibition rates on 5-hydroxymethyl-2-furaldehyde (5-HMF), glyoxal (GO), methylglyoxal (MGO), Nε-carboxymethyl lysine (CML), and Nε-carboxyethyl lysine (CEL) were 60.8%, 27.12%, 23.44%, 57.7%, and 31.28%, respectively. After 21 d of storage, the levels of 5-HMF, GO, MGO, CML, and CEL in BFM with TP were 46.3%, 9.7%, 20.6%, 5.2%, and 24.7% lower than the control group, respectively. Moreover, a smaller change occurred in their color and the browning index was lower than that of the control group. The significance of this study was to develop TP as additives to inhibit the production of MRP in brown fermented yogurt without changing color and flavors, thereby making dairy products safer for consumers.

Determination of hydroxymethylfurfural in Turkish honeys, pekmez (grape molasses), and jam samples byhigh‐performanceliquid chromatography with diode array detection

Hydroxymethylfurfural (HMF) is a chemical contaminant that is not naturally present in carbohydrate-containing food samples. The HMF amounts were changed between 4.8 and 214.1 mg/kg in honey; between 7.8 and 204.0 mg/kg in pekmez (grape molasses); between 5.9 and 22.4 mg/kg in strawberry jam; between 6.0 and 65.4 mg/kg in apricot jam; and between 9.2 and 55.9 mg/kg in cherry found by HPLC. The linear calibration plot of HMF was ranged from 0.05 to 10.0 μg/ml. The correlation coefficient was found to be 0.99997. LOD and LOQ values were found to be 12.0 and 40.0 ng/ml, respectively. According to the experimental results, HMF amounts of four honey samples, three pekmez (grape molasses) samples, one apricot jam, and one cherry jam for investigated samples were found to be higher than the permission amount of Turkish Food Codex. Novelty impact statement Based on experimental results in this study, if the honey is in a transparent package such as a glass, it should be stored in a dark environment. It would be healthier to prefer molasses produced by reliable brands at low temperatures under vacuum instead of molasses made with traditional methods in open boilers. Generally, since jams with high HMF amount have an overcooked or even burnt flavor, this is an extremely negative situation for consumers.

The effect of intense pulsed light on the sensory properties of nonfat dry milk.

Our objectives were to examine (1) how intense pulsed light (IPL) processing parameters (exposure time and initial temperature) affected aroma, flavor, and mouthfeel of nonfat dry milk, (2) which levels of each parameter produced aroma, flavor, and mouthfeel changes from an untreated control sample, and (3) whether minimal or intense processing conditions produced a noticeable appearance change from the control. Four exposure times(1, 2, 3, and 4 passes through the IPL chamber) and three initial temperatures (25, 30, and 35℃) were studied with untreated milk powder as the control. The samples were prepared as both milk powder and reconstituted milk for sensory evaluation. Using standard evaluating protocols, trained descriptive analysis panelists rated the aroma, flavor, and mouthfeel of these samples. Panelists compared the appearance of the IPL-treated samples that underwent a minimal or intense processing condition to the control by using a two-out-of-five difference test. Increasing the exposure time led to increased intensities of overall flavor, burnt flavor, and umami taste in both milk powder and reconstituted milk, while increasing temperature increased animal and sulfur aromas in reconstituted milk only. Compared to the control, all levels of exposure time at any initial temperature resulted in increased aroma and flavor including cardboard aroma, sulfur aroma, and brothy flavor in both milk powder and reconstituted milk. Only the 4-pass exposure at the initial temperature of 25℃ changed the appearance of milk powder. However, the appearance change was not noticeable in reconstituted milk. PRACTICAL APPLICATION: The standard evaluation protocols and lexicons provide useful tools for research on milk powder. Additionally, the understanding of critical factors impacting sensory properties will contribute to a better implementation of this decontamination technology.

Effect of the roasting degree on flavor quality of large-leaf yellow tea

Roasting is crucial for producing large-leaf yellow tea (LYT) as it substantially affects chemical composition and sensory quality. However, the effect of roasting degree on LYT flavor quality is not clear. To investigate the effect of roasting degree on LYT flavor, the odor profiles and sensory evaluations of LYTs produced with small fire, medium fire and old fire roasting (OF) were determined. The OF was essential for the formation of LYT flavor with strong roasted, nutty, woody odors and weak fatty, fruity odors, and retaining high levels of GCG, total volatiles and heterocyclic compounds. Furthermore, the characteristic crispy-rice-like odor was only found in LYT with OF treatment and burnt flavor was missing. 2,3-Diethyl-5-methylpyrazine, trans-β-ionone with odor activity value above 1600 and 39 respectively offered roasted, floral odors, respectively in LYT. The current results provide a scientific basis for understanding the reactions that occur during the conventional production of LYT.

Beef Flavor Evaluation on Top Loin Steaks, Sirloin Steaks, Chuck Roasts, and 80/20 Ground Beef Over The Retail Case

ObjectivesConsumer acceptability in meat flavor is one of the driving factors of acceptability. Many studies have found factors that affect beef flavor, but little is known about variability of major beef cuts in the retail meat case where meat is displayed, and customers can choose from.Materials and MethodsFour beef cuts (chuck roast, top sirloin steaks, top loin steaks, and 80/20 ground beef) were obtained from retail stores in Miami, Los Angeles, Portland, New York, and Denver within a 2-mo period. The study wanted a variety of samples that were from different production systems or contained certain claims that would be available to customers. The meat was shipped with dry ice and stored at –9°C. For evaluation steaks, roasts, and ground beef were thawed 24 h at 4°C. Prior to cooking, chuck roasts were cut 10.16 × 12.7cm from the center of the roast. Each ground beef sample was formulated into 3, approximately 150 g patties. Chuck roasts were placed in a roasting pan on a roasting rack and 2 cups of water. Beef steaks and ground beef patties were cooked on a stovetop grill and cooked to 71°C, steaks and patties were flipped when temperature reached 35°F. Chuck roasts were cut into 1.27cm cubes with no visible connective tissue, fat, or outside browning. Steaks were cut into 1.27cm cubes with no connective tissue or fat. Ground beef patties were cut into 6 wedges. Panelists were served either 2 wedges or 2 1.27 cm samples for evaluation. An expert trained descriptive flavor and texture sensory panel was conducted where panelists evaluated beef flavors and textures. Beef flavor and texture attributes were analyzed using SAS (version 9.4, SAS Institute, Inc., Cary, NC) and principal component (PCA) bi-plots were generated using XLSTAT (Addinsoft, Inc., Long Island City, NY) using P &lt; 0.05.ResultsChuck roasts were associated with bloody/serumy flavor aromatics. Ground beef patties were clustered with fat-like, overall sweet, green hay, and buttery flavor aromatics. Top sirloin steaks samples were more highly associated with off flavors such as liver, cardboardy, and sour flavor aromatics. Top loin steaks were clustered with positive attributes such as umami, beef flavor identity, and brown, roasted flavor aromatics. For the PCA biplot, factor 1 accounted for 60% and factor 2 accounted for 28% of variation. Ground beef was higher (P &lt; 0.0001) in brown, fat like, green hay, sour milk/sour dairy, flavor aromatics, and had more salty and sweet basic taste than the other cuts. Ground beef patties had the least amount (P &lt; 0.0001) of bloody/serumy, metallic, and liver like flavor aromatics. Chuck roasts had the least (P &lt; 0.0001) beef flavor id, brown, roasted flavor aromatics and salt and umami basic taste. Sirloin steaks had the lowest (P &lt; 0.0001) fat like flavor aromatic and the highest levels (P &lt; 0.0001) of burnt and cardboardy flavor aromatics and bitter and sour basic taste. Sirloin steaks and chuck roasts had more metallic and liver like (P &lt; 0.0001) flavor aromatics than other cuts. Top loin steaks were intermediate in flavor attributes.ConclusionFlavor descriptive attributes of four beef cuts differed. Results indicated that chuck roasts and top sirloin steaks were associated with negative flavor attributes. Ground beef contained sweeter, fat like attributes with exceptions of green hay, while top loin steaks were associated with more positive beef flavor attributes.

Steak Thickness, Cook Surface Temperature and Quality Grade Affected Top Loin Steak Consumer and Descriptive Sensory Attributes

Beef flavor attributes of USDA Top Choice and Select beef top loin steaks were evaluated that differed in thickness (1.3 or 3.8 cm) and grill surface temperature (177 or 232°C) when cooked on a commercial flat top grill. A trained descriptive attribute panel and consumer sensory panels were used to evaluate steak flavor and texture. As thickness and temperature increased, beef identity and brown/roasted flavor aromatics increased (P &lt; 0.05). Steaks cooked at 232°C and cut 3.8-cm thick had the highest (P &lt; 0.05) levels of burnt flavor and bitter basic tastes. Thicker steaks cooked at 177°C had more intense umami basic taste and beef identity (P &lt; 0.05). Steaks cut 1.3 cm had lower levels of beef identity and brown/roasted flavor aromatics and the thin cut steaks cooked at 177°C had more sour basic taste (P &lt; 0.05). Consumers rated 232°C, 3.8 cm steaks lowest (P &lt; 0.05) for overall, beef flavor, overall flavor, and grilled flavor liking; whereas, the 177°C, 3.8 cm steaks were highest (P &lt; 0.05) in beef flavor liking. Beef identity, brown/roasted, bloody/serumy, fat-like, umami, sweet, salty, overall sweet, overall tenderness, and muscle fiber tenderness were positive attributes, and metallic, bitter, and burnt were negative attributes in predicting consumer overall liking. Thick steaks cooked at low temperatures or thin steaks cooked at high temperatures resulted in more positive sensory panel traits and consumer liking scores.

Identification of 2-Hydroxymethyl-3,6-diethyl-5-methylpyrazine as a Key Retronasal Burnt Flavor Compound in Soy Sauce Aroma Type Baijiu Using Sensory-Guided Isolation Assisted by Multivariate Data Analysis.

The burnt flavor (overcooked rice flavor) is often retronasally perceived during the soy sauce aroma type Chinese Baijiu (Chinese distilled spirit) tasting and regarded as an important quality marker of the Baijiu. The sensory-guided isolation approach assisted by multivariate data analysis was applied to identify the compounds responsible for the retronasal burnt flavor in the Baijiu. Using two-dimensional offline high performance liquid chromatography separation and taste dilution analysis, a subfraction with the highest burnt flavor intensity was isolated from the Baijiu sample. In the subfraction, six potential flavor compounds were detected by ultra performance liquid chromatography-mass spectrometry. The most probable burnt flavor compound was screened by projection to latent structure regression analysis of the correlation between the potential compounds and their impact on burnt flavor. The target compound was identified as 2-hydroxymethyl-3,6-diethyl-5-methylpyrazine by means of high-resolution mass spectrometry and chemical synthesis. Sensory evaluation revealed a relatively low burnt flavor threshold of 2.89 μmol/L in 53% ethanol aqueous solution. On the basis of the dose-overthreshold factor and addition experiment, this compound was confirmed as the key contributor to the burnt flavor of soy sauce aroma type Baijiu.

Sensory Shelf Life of Dulce de Leche

The objectives of this research were to determine the sensory cutoff points for dulce de leche (DL) critical descriptors, both for defective off-flavors and for storage changes in desirable attributes, and to estimate the shelf life of DL as a function of storage temperature. The critical descriptors used to determine the cutoff points were plastic flavor, burnt flavor, dark color, and spreadability. Linear correlations between sensory acceptability and trained panel scores were used to determine the sensory failure cutoff point for each descriptor. To estimate shelf life, DL samples were stored at 25, 37, and 45°C. Plastic flavor was the first descriptor to reach its cutoff point at 25°C and was used for shelf-life calculations. Plastic flavor vs. storage time followed zero-order reaction rate. Shelf-life estimations at different temperatures were 109 d at 25°C, 53 d at 37°C, and 9 d at 45°C. The activation energy, necessary to calculate shelf lives at different temperatures, was 14,370±2080 cal/mol.

SENSORY AND PHYSICAL PROPERTIES OF EXTRUDED POTATO PUFFS1

ABSTRACTAlthough extrusion is widely used for snack foods, there are few descriptive sensory analysis studies of extrudates. This study investigated the effects of potato granule type (flour or flakes), feed moisture content (16%, 18% and 20%) and addition of oil (0%, 2% and 4%) on sensory attributes of extrudates. Generalized Procrustes analysis (GPA) and Principal Component analysis (PCA) were used to describe the relationship among the sensory attributes. Additionally, GPA described the relationship between selected sensory and physical variables. Feed moisture content, as a primary factor, and added oil, as the secondary, affected the puff characteristics. High feed moisture puffs were high in hardness and chewiness, whereas low moisture ones were high in brownness, burnt flavor and fracturability. Added oil changed sensory expansion with relation to low feed moisture. Using GPA, physical properties related to appearance, color and texture were matched with corresponding sensory attributes.

Enzymatic and Autoxidation of Defatted Peanuts

ABSTRACTGround, blanched, raw, and roasted peanuts with varying oil contents were analyzed for oxidation products. Peroxide values (PV) of blanched, ground raw (BRAW) peanuts, demonstrating enzymatic oxidation, and heat‐treated rancid roasted peanuts (RRST), demonstrating autoxidation, exhibited decreases (p ≦ 0.05) with decreasing oil content. The Oxidative Stability Index (OSI) time at 110 °C increased (p &lt; 0.05) with decrease in oil content of raw (BRAW) and roasted (BRST) ground peanuts. A higher OSI indicated more oxidative stability, thereby supporting the hypothesis of higher potential for autoxidation at higher oil contents. In addition, BRST exhibited a shorter OSI than BRAW, indicating slower autoxidation in BRAW. Roasted peanutty odor, burnt odor, and roasted peanutty flavor, rancid/oxidized flavor, and burnt flavor scores of rancid roasted peanuts decreased (p ≦ 0.05) with decreasing oil content.

Evaluation of compounds contributing characterizing fishy flavors in fish oils

AbstractsVacuum steam‐deodorized fish oils oxidized under flourescent light (950 lux) at 21°C initially developed green flavors which were caused principally by t,c‐2,6‐non‐adienal, but some green‐type flavor notes were contributed byt‐2‐hexenal and 1,c‐5‐octadien‐3‐one. Diminishment of green flavor notes resulted from the depletion of 2,6‐nonadienal and the formation ofc‐4‐heptenal (&gt;1 ppm) which contributed oxidized, burnt flavor notes. Concomitant formation oft,c,c‐ andt,t,c‐2,4,7‐decatrienal (&gt;1 ppm) yielded characterizing burnt/fishy or cod liver oil‐like flavors in fish oils. Two unidentified compounds exhibiting minnow‐bait‐bucket and trout‐like odor qualities, respectively, were encountered in oxidizing fish oils. Hexanal, 2,4‐heptadienals and 2,4‐decadienals contributed general oxidized, painty flavors to fish oils.

FLAVOR QUALITY IN EXPLOSION PUFFED DEHYDRATED POTATO. 2. Flavor Contribution of 2‐Methylpropanal, 2‐Methylbutanal and 3‐Methylbutanal

SUMMARY– Headspace vapor components previously associated with the intensity of an off‐flavor in explosion puffed dehydrated potatoes were added to potatoes lacking the off‐flavor to determine the flavor contribution of these compounds. 2‐Methylpropanal produced a characteristic wet fur flavor note while 2‐ and 3‐methylbutanal modified this flavor and contributed burnt flavor notes. While these flavor notes resembled some elements of the puffing off‐flavor, the total off‐flavor at its normal intensity could not be simulated by combinations of these compounds in potato at realistic concentrations. Acetone, which is also present in the headspace vapor of explosion puffed dehydrated potatoes, was found as a major headspace component of fresh boiled potatoes. This compound and smaller amounts of 2‐ and 3‐methylbutanal were produced in overcooked fresh potatoes which lacked the puffing off‐flavor.

Studies on the Source-Origin of Activated Flavor in Milk

Milk unduly exposed to radiation, either natural or artificial, will acquire a flavor defect called activated, sunshine, or burnt. This defect is to be differentiated from that referred to as oxidized fiavor. Homogenized milk is known to acquire the flavor more readily than unhomogenized milk. Excessive or improper exposure of milk to artificial radiation is a frequent cause for occurrence of the flavor. The ultimate prevention of the development of the flavor, however, necessitates further information concerning its origin and method of development. In the study presented here, milk or milk products, and other substances were exposed for prolonged periods to radiation so as to accentuate the intensity of the flavor, and permit its ready identification and isolation. Reviews of the literature on the activated flavor of milk have been included in previous reports (4, 8). I t was pointed out that the flavor originates with the protein fraction of milk, and it was indicated that the flavor which results from undue exposure to ultra-violet radiation is identical or very similar to the burnt or sunshine flavor caused by exposure of milk to sunlight. Radiation is known to cause destructive effects upon proteins in general and to produce disagreeable flavors and odors. Casein and lactalbumin have been shown to develop the typical activated flavor of milk. The present study is concerned with ascertaining the specific source of the flavor.

Studies on the Activated Flavor of Milk

Summary These studies indicate that heating milk to temperatures above 150° to 160° F. and cooling enhances the activated flavor of the subsequently unduly irradiated milk. When irradiation and homogenization are both used in processing milk better results are secured if irradiation precedes homogenization. Altering the “salt balance” of the milk by addition of various substances failed to increase or decrease the flavor intensity of the subsequently irradiated milk. Nitrogen and Avenex inhibited development of the flavor. It was found possible to remove the activated flavor from milk by oxidation. This was best accomplished by adding to the irradiated milk two to three parts per million of copper and then bubbling air through the milk at 140−145° F. The typical activated odor was produced by irradiation of aqueous solutions of egg white or of gelatin giving additional evidence that the protein fraction of milk is probably the parent substance of the flavor. The studies indicate that the activated flavor of milk unduly exposed to ultra-violet radiation is identical or practically identical with the burnt flavor which develops in milk exposed to sunlight. Evidence is given that if milk bottles can be devised which will eliminate all wave lengths of light less than 4600 A they will be effective in inhibiting development of the activated flavor caused by exposure of milk to sunlight.

The Relation of Certain Plant Processes to Flavor Development in Market Milk

Summary The relation between a number of plant processes and the quality of market milk as indicated by its flavor has been studied. In the absence of more suitable methods the flavor of the milk was determined organoleptically. One of the most important of the plant processes bearing upon the quality of market milk is the use of an effective grading system. Such a system should provide for bacterial, flavor, and temperature control in the raw milk up until the time of delivery. Pasteurization improves the flavor of most raw milk. Continued heating at 142°F. for over one hour, however, may result in a noticeable cooked flavor. Milk should not be brought into contact with either iron or copper surfaces. Benedict nickel also may have a detrimental effect upon milk flavor. The development of a tallowy flavor in milk is closely associated with metal contamination. Glass and Allegheny metal have practically no ill effects on milk flavor. Two kinds of flavor defects may occur in milk exposed to sunlight, one a tallowiness, and the other a burnt flavor. Diffuse light is an important factor in the development of tallowy flavor in milk, especially that containing an added copper salt. The use of chlorin sterilizers on farm and plant equipment should be confined to those of a non-corrosive. nature. In no case should the-disinfectant be added directly to the milk, and all utensils and equipment treated with chlorin sterilizers should be rinsed with uncontaminated water before adding the milk. Otherwise, puckery, unclean, or medicinal flavors may develop. The odor and flavor of phenol, when present in milk is greatly intensified by the presence of chlorin in the form of sodium hypochlorite.