Retail lighting and packaging influence consumer acceptance of fluid milk

Little is known about the effect of retail light-emitting diode (LED) exposure on consumer acceptance of milk. The study objective was to determine effects of fluorescent and LED lighting under retail storage conditions on consumer acceptance of milk. Consumer acceptance of milk stored under retail conditions was determined through sensory evaluation (2 studies; n = 150+ each) and analytical measures (dissolved oxygen, secondary oxidation products, riboflavin retention). Study 1 evaluated milk stored in high-density polyethylene (HDPE) packages for 4 h under LED light (960 lx). Commercially available HDPE package treatments included translucent HDPE (most commonly used), white HDPE [low concentration (1.3%) TiO₂], and yellow HDPE; in addition, HDPE with a higher TiO₂ concentration (high white; 4.9% TiO₂) and a foil-wrapped translucent HDPE (control) were tested. Translucent and control packages also were tested under fluorescent light. Study 2 evaluated polyethylene terephthalate (PET) packages for 4 h under fluorescent and LED light (1,460 lx). The PET packaging included 2 treatments (medium, 4.0% TiO₂; high, 6.6% TiO₂) as well as translucent HDPE (exposed to fluorescent), clear PET (fluorescent and LED), and light-protected control. Overall mean acceptability of milk ranged from “like slightly” to “like moderately” with significantly lower acceptability for milk exposed to fluorescent light. Milk in HDPE and PET packages had comparable overall acceptability scores when exposed to LED light. Only the fluorescent light condition (both PET and HDPE) diminished overall acceptability. Fluorescent light exposure negatively influenced flavor with significant penalty (2.0–2.5 integers) to overall acceptability of milk in translucent HDPE and clear PET. The LED also diminished aftertaste of milk packaged in translucent HDPE. Changes in dissolved oxygen content, as an indication of oxidation, supported the observed differences in consumer acceptance of milk stored under fluorescent and LED light. Consumers like the flavor of fresh milk, which can be protected by selecting appropriate packaging that blocks detrimental light wavelengths.     

Effectiveness of poly(ethylene terephthalate) and high-density polyethylene in protection of milk flavor.

The development of certain off-flavors in whole milk (3.25% milk fat) as related to packaging material [glass, high-density polyethylene (HDPE), amber poly(ethylene terephthalate) (PETE), clear PETE, and clear PETE-UV] were evaluated after exposure to fluorescent light (1100 to 1300 lx) for 18 d at 4 degrees C. Control samples packaged and stored under identical conditions were wrapped in foil to prevent light exposure. Selected flavor compounds in milk were measured analytically on d 0, 7, 14, and 18 of storage, while intensities of "oxidation," "acetaldehyde," and "lacks freshness" off-flavors were determined by sensory analysis at the same intervals. In light-exposed samples, oxidation off-flavor was significantly lower when packaged in amber PETE versus other containers. Milk packaged in HDPE containers showed a significantly higher level of oxidation off-flavor than milk packaged in PETE-UV containers but not higher than clear PETE or glass containers. No significant difference in acetaldehyde off-flavor was found between package material treatments (exposed or protected). Acetaldehyde concentration never exceeded flavor threshold levels, regardless of packaging material. Amber and PETE-UV materials proved to be a competitive packaging choice for milk in preserving fresh milk flavor.     

Effect of the addition of air-classified barley flours on the lipid stability of bakery products

Whole grains are a potential source of dietary antioxidants, and their phenolic compounds play a potential role in the prevention of lipid oxidation. In the present study, the barley coarse fraction was tested as a source of phenolic compounds to minimize lipid oxidation in bakery products (tarallini) during storage. The content of phenolic compounds in wheat and barley flours and in their mixtures was evaluated by capillary electrophoresis. Three recipes of tarallini were formulated containing different levels of barley coarse fraction (0, 20, 50%, w/w) and either extravirgin olive oil or sunflower oil. Samples were stored for 6 months and analysed every 3 months. The peroxide value was used to establish the primary oxidation state; secondary oxidation products were also evaluated (oxidized fatty acid and diene and triene conjugated by UV). All samples showed an increase in lipid oxidation during storage. The increase in peroxide values after 6 months was in the range of 183–574%. Tarallini prepared with sunflower oil showed the highest lipid oxidation. Antioxidant effects were not observed with the coarse fraction phenolic compounds.     

Oxidative stability of bovine milk determined by individual variability in herd irrespective of selenium status

The effect of supplementing dairy cows with organic selenium (25 mg day^?1) on oxidative stability of milk when exposed to Cu(II) ions or to fluorescent light was evaluated using solid-phase micro-extraction gas chromatography with flame ionisation detection. Neither formation of volatile lipid (hexanal) and protein (dimethyl disulfide) oxidation products nor radical scavenging activity was affected by selenium supplementation. We found that other factors must be determinant for the oxidative stability of milk, and that these factors vary considerably between individual cows. Milk from two cows that were either sensitive or resistant to oxidation was compared in an attempt to identify the molecular basis for these differences. It was found that oxidation of milk could not solely be explained on the basis of fatty acid composition, or content of low molecular weight antioxidants, such as uric acid, ascorbic acid, and tocopherol.     

Lipolysis and Oxidation in Ultra‐High Temperature Milk Depend on Sampling Month,Storage Duration,and Temperature

During storage, some factors (for example, storage duration and temperature) can affect milk stability and consumer acceptability. Thiobarbituric acid reactive substances (TBARSs), lipid classes, and fatty acid profiles in stored ultra‐high temperature (UHT) milk were analyzed to assess the effects of storage time and temperature on lipid oxidation and lipolysis. With storage duration up to 12 months, the milk fat phase was separated and showed high levels of oxidation and lipolysis, manifested as increased levels of TBARS and free fatty acids. High oxidation levels decreased the percentage of unsaturated fatty acids (UFAs) in triacylglycerol and phospholipids. Higher storage temperatures (20, 30, and 37 °C) resulted in a higher degree of fat aggregation, oxidation, and lipolysis compared with refrigerated storage (4 °C). Additionally, sampling month of raw milk (May, July, and November) affected the lipid profiles of UHT milk during storage, with more UFA oxidized in July than in the other 2 months.     

Lipid and fatty acid composition and lipid peroxidation of sublimated mare's milk after its long term preservation using antioxidants]

Sublimated mare's milk was stored with and without antioxidants during one year. The antioxidants quercetin and bisalcophen were introduced before drying in a dose of 0.02% relative to milk fat. Lipid, fatty acid composition and lipid peroxidation (LPO) parameters (diene and triene conjugates, total lipid oxidation) were studied immediately after drying and after 3, 6, 9 and 12 months of storage. No significant changes were detected in lipid, fatty-acid composition and LPO rate after 3 months of dried milk storage without additives. Significant deterioration of lipid, fatty-acid composition, increase of LPO and oxidation of milk were recorded after 6 months. Addition of quercetin and bisalcophen promoted stabilization of fatty-acid composition and prolonged the term of sublimated mare's milk storage.     

Production and oxidative stability of a human milk fat substitute produced from lard by enzyme technology in a pilot packed-bed reactor

Residence time and time of production were investigated during the enzymatic production of a specific structured lipid/human milk fat substitute (SL-HMFS), on a kg scale, made from lard and soybean oil fatty acids, using a packed-bed reactor and short path distillation. There were no effects of residence time or time of production on C18:2 and C18:3 incorporation or on acyl migration in the sn-2 position. In addition, the SL-HMFS was compared to commercial human milk fat substitute (HMFS) regarding fatty acid composition, content of antioxidants and oxidative stability. Fats were stored at 60 °C for four days and the oxidative stability evaluated by analysis of peroxide value (PV) and volatile secondary oxidation products. SL-HMFS had a lower oxidative stability than did commercial HMFS products or lard, probably due to a lower level of tocopherol in SL-HMFS.     

Evaluation of lipid oxidation in spaghetti pasta enriched with long chain n−3 polyunsaturated fatty acids under different storage conditions

This study investigated lipid oxidation in spaghetti enriched in long chain n−3 polyunsaturated fatty acids (LC n−3 PUFA) by the addition to semolina of an integrator containing eicosapentaenoic acid and docosahexaenoic acid. Two oxidative parameters were evaluated: peroxide value (PV), to assess primary oxidation and oxidised fatty acids to quantify secondary oxidation products. Functional spaghetti had a shelf life comparable to control pasta. LC n−3 PUFA were not significantly implicated in the onset of oxidation in spaghetti stored under daylight and accelerated oxidation in a laboratory heater. Storage decidedly affected shelf life: PV in functional spaghetti increased from 7.1 to 43.4 meq O₂/kg of fat under light exposure over 12 months, and from 7.1 to 16.2 meq O₂/kg under accelerated ageing at 55 °C for 27 days, reproducing about 18 months at room temperature. Oxidised fatty acids increased in fortified spaghetti from 4.8 to 13.8 g/100 g of fat under light exposure over 12 months and from 4.8 to 7.8 g/100 g of fat at 55 °C in 27 days. The high sensitivity of spectrophotometric and chromatographic analytical methods permitted the evaluation of primary and secondary oxidative derivatives in small amounts of fat.     

Chemical changes in almonds throughout storage: modeling the effects of common industry practices

Further investigations of almond degradation under typical industrial storage conditions from a quantitative perspective are warranted. This study modeled effects of packaging, temperature (TEMP), relative humidity (RH) and roasting on chemical attributes of almonds stored according to common industry practices throughout 16 months. Roasted samples were stored in high-barrier bags (HBB) or polypropylene bags (PPB) at multiple combinations of TEMP and RH. Raw samples were held in unlined cardboard cartons (UC) or PPB under the same conditions. Almonds were assessed bimonthly for oxidation products, free fatty acids, moisture content and water activity. Results indicated roasting almonds improved quality preservation. Models showed HBB (rather than PPB) to provide benefits to stability comparable to reductions in storage TEMP of ~15 to 30 °C. PPB (rather than UC) showed benefits to peroxide formation of similar magnitude. Our data shows HBB to be a superior packaging choice, and UC to associate with the greatest rates of degradation.     

Lipid and cholesterol oxidation in Chinese-style sausage using vacuum and modified atmosphere packaging

The oxidation of lipid and cholesterol in Chinese-style sausage in vacuum packaging (VP) and modified atmosphere packaging (MAP) stored at 4°C and 15°C, respectively, for 5 months was investigated. The 2-thiobarbitaric acid reactive substance (TBARS) and peroxide value (POV) of sausage were variable with packaging treatments during storage. TBARS and POV in sausage stored at 15°C were significantly greater (p < 0·05) than at 4°C, and the MAP treatment was more stable than the VP treatment. In addition, the polyunsaturated fatty acids (PUFA) in sausage decreased with storage for both treatments. The content of cholesterol decreased significantly after 3 months of storage. 7-β-hydroxycholesterol, 7-ketocholesterol and 22-ketocholesterol were the major cholesterol oxidation products (COPs), but there was no detectable (< 1 μg/100 g) 25-hydroxycholesterol or cholestanetriol with either treatment.     

Effect of oxygen absorber, nitrogen flushing, packaging material oxygen transmission rate and storage conditions on quality retention of raw whole unpeeled almond kernels (Prunus dulcis)

The present study investigated the effect of active packaging, nitrogen flushing, container oxygen barrier and storage conditions on quality retention of raw whole unpeeled almonds. Almond kernels were packaged in: a) polyethylene terephthalate//low-density polyethylene (PET//LDPE), and b) low-density polyethylene/ethylene vinyl alcohol/low-density polyethylene (LDPE/EVOH/LDPE) pouches under N_2, with or without an oxygen absorber, heat-sealed and stored for a period of 12 months. Quality parameters monitored were: peroxide value (PV), hexanal content, color, fatty acid composition and volatile compounds. PV ranged between 0.17 for fresh almonds and 9.22 meq O₂/kg oil for almonds packaged in PET//LDPE pouches under N₂ exposed to light at 20 °C after 12 months of storage. Respective values for hexanal were <28.5 μg/kg and 4.88 mg/kg. Polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) increased with a parallel decrease of monounsaturated fatty acids (MFA) after 12 months of storage in all treatments. Likewise, volatile compounds such as aldehydes, ketones, alcohols, alkanes and aromatic hydrocarbons increased indicating enhanced lipid oxidation. Color was the parameter least affected. Use of the oxygen absorber provided a shelf life of at least 12 months for all samples irrespective of container oxygen barrier, lighting conditions and storage temperature.     

Relation between types of packaging,frozen storage and grilling on cholesterol and fatty acids oxidation in Atlantic hake fillets (Merluccius hubbsi)

Two different commercial samples of frozen and packaged, in low and high-oxygen permeability packaging, Atlantic hake fillets were stored at −18 °C for 4 months and the intensity of lipid oxidation, as well as the formation of cholesterol oxidation products (COP), during storage and subsequent grilling were studied. Raw fillets at the initial time of storage showed low total COP levels, however, after 120 days of storage the concentrations were raised significantly, under both packed conditions. During freezing and subsequent grilling there was a significant decrease (p < 0.02) in the contents of the cholesterol and polyunsaturated fatty acids in all the hake samples. Correlations were found between the cholesterol and fatty acid parameters and cholesterol oxides formation during storage and heat treatment. The commercial frozen storage with a low-oxygen permeability packaging was more effective in preventing lipid oxidation than high-oxygen permeability packaging, with less accented cholesterol degradation as well as cholesterol oxides formation.     

Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at ?20 and ?30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of ?20 °C compared with samples stored at ?30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at ?20 than ?30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both ?20 and ?30 °C but was greater at ?20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at ?20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish. © 2002 Society of Chemical Industry     

Prevention of lipid oxidation in muscle foods by milk proteins and peptides: A review

Muscle foods (especially fresh meat, precooked, and restructured meat products) are highly prone to lipid oxidation, which ultimately leads to certain problems, viz. discoloration, off-flavor, drip losses, loss of essential fatty acids and vitamins, and generation of toxic products. These problems can be minimized with the help of various agents and or techniques such as use of natural/synthetic antioxidants, metal chelating agents, physical conditions, vacuum packaging, and encapsulation techniques. Among these, the role of synthetic antioxidants is quite debatable due to certain health risks to humans. Among the natural molecules, milk proteins and their bioactive peptides offer a promising potential for the meat industry. Various forms of milk proteins and peptides including caseinates, whey proteins, skim milk, and milk co-precipitates can be used to prevent lipid oxidation in meat products either in the form of added ingredients or as edible coatings. However, in addition to prevention of lipid oxidation, they also provide nutritional benefits and improve the technological processing and shelflife of meat and meat products. This review focuses on the utilization, mechanism of action, and efficacy of milk proteins and peptides to inhibit lipid oxidation in muscle food products.     

Effect of storage and packaging on fatty acid composition and oxidation in dry fermented sausages made with added olive oil and antioxidants

Dry fermented sausages produced by a partial substitution of pork backfat with pre-emulsified olive oil were manufactured and stored (2 and 5 months) using different packaging conditions (aerobic/vacuum piece/vacuum slices) in order to evaluate the intensity of the oxidation process. Also the effect of the addition of butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA) to one of the modified batches was studied. Addition of olive oil, especially with antioxidants, was more effective than using vacuum storing methods in avoiding lipid oxidation during storage. After 5 months of storage at 4 °C, the combination of the increase in oleic acid and the preservation of PUFA by the antioxidant activity of the olive oil emulsion and antioxidants (when added), lead to better MUFA+PUFA/SFA ratios in olive oil containing sausages (1.90-1.98 g/100 g fatty acids) and particularly in antioxidants containing sausages (2.02-2.16 g/100 g) than in control ones (1.72 g/100 g). Vacuum packaging of the piece was the best method to minimise formation of lipid oxidation volatile compounds.     

Flavor and stability of pasteurized milk with elevated levels of conjugated linoleic acid and vaccenic acid

The objectives of this study were to determine if flavor differences between 2% fat pasteurized milks with and without naturally enhanced vaccenic acid (VA) and cis-9, trans-11 conjugated linoleic acids (CLA) levels could be detected over the commercial shelf life of the product and to determine if milk with elevated VA and cis-9, trans-11 CLA levels was more susceptible to development of light-induced oxidative flavor defects. Cows were fed a control diet or the same ration supplemented with 2% soybean oil and 1% fish oil (CLA diet). The milk, standardized to 2% fat, was pasteurized, homogenized, and stored in plastic containers at 4 degrees C. Oxidation was induced by exposing half of the containers to light. Testing was conducted at 1, 7, and 14 d postpasteurization. Average cis-9, trans-11 CLA content of the milks from the control and CLA diet groups was 0.52 and 4.74 g/100 g of fatty acids, respectively (8-fold increase). Average VA content of the milk from the control and CLA diet groups was 1.43 and 12.06 g/100 g of fatty acids, respectively (7.5-fold increase). Together, VA plus CLA represented almost 17% of the total milk fatty acids. There was no effect of light exposure on fatty acid composition initially or over the 14-d storage period. Although VA, cis-9, trans-11 CLA, and degree of unsaturation were significantly elevated in the milk from the CLA diet group, untrained panelists were unable to detect flavor differences initially or over time in 15 of 16 triangle test evaluations. Similarly, sensory results indicated no difference in susceptibility to the development of oxidized off-flavors between the milk from the control and CLA diet groups, even when oxidation was induced by light exposure.     

Cholesterol photosensitised oxidation of horse meat slices stored under different packaging films

The effect of the type of packaging film (transparent vs. light-protecting red film) was evaluated on the formation of cholesterol oxidation products (COPs) in refrigerated horse meat slices stored in retail conditions under light exposure for 8 h. In meat wrapped with a transparent film, COPs increased from 233 (control) to 317 μg/g of fat, whereas the red film delayed cholesterol oxidation and offered protection against COPs formation, since COPs decreased from 173 (control) to 139 μg/g of fat after 8 h of light exposure. In addition, light opened the epoxy ring and led to the formation of triol, which was actually absent at T_0. A proper packaging film may represent a useful strategy to retard oxidative degradation in a light-sensitive, high pigment- and fat-containing food, such as horse meat.     

Impact of preservation and different packaging conditions on the microbial community and activity of Kefir grains

Kefir is a cultured milk product that is produced by a mixed acidic and alcoholic fermentation by microbes found within Kefir grains. The aim of this study was to evaluate three different packaging materials in their ability to retain the viability and activity of the grains over an extended storage period. The impact of the different packaging and storage conditions on the microbial community of the grains was also determined. Kefir grains were lyophilized, packaged in three different packaging materials, including low-density polyethylene film (LDPE), oriented polyester film (OPET), and methallized oriented polyester film (MOPET) and stored for 3 months at room temperature. Activity tests, including pH, titratable acidity (%TA), lactose and lactic acid content over a 10 and 18 h fermentation period were used to evaluate the acidification activity of the lyophilized grains. Selective media, morphology and physiological characteristics were used to obtain the enumeration values and to identify the microbes present in the packaged and stored grains. Overall, the best retention of the fermentation activity was found for the MOPET film. The OPET packaging film provided the best preservation of the microbial composition.     

Stability of linseed oil and antioxidants containing dry fermented sausages: A study of the lipid fraction during different storage conditions

Different packaging conditions (aerobic, vacuum and modified atmosphere) were evaluated in order to study the stability of the lipid fraction of dry fermented sausages manufactured with a partial substitution of pork backfat by linseed oil and antioxidants. After 5 months of storage, α-linolenic acid was better preserved by vacuum and MAP (7.32 and 7.74g/100g fatty acids, respectively) than in aerobic conditions (6.15g/100g fatty acids), without significant differences to values obtained after 2 months of storage for this acid. At the end of the storage, (n-6)/(n-3) fraction in sausages with linseed oil was in all cases lower than 3, in contrast to values obtained for control products that were all higher than 15. Better PUFA/SFA ratios were also observed in modified sausages (0.6-0.7g/100g fatty acids) than control ones (0.3-0.4g/100g fatty acids). No signs of lipid oxidation measured by TBARs and peroxides were detected for modified sausages regardless the packaging system used (TBARs values lower than 0.25ppm and peroxides lower than 4meq O(2)/kg), pointing at a high effectiveness of the antioxidants. Furthermore, vacuum and MAP prevented 2,4-decadienal formation. Nutritional benefits of linseed oil and antioxidants containing products were maintained after 5 months of storage.