Frozen Storage Performance of Cooked Cultivated Mussels (Mytilus edulis L.)—Influence of Ascorbic Acid and Chelating Agents

The usefulness of ascorbic acid and chelating agents in retarding sensory deterioration and progression of oxidative rancidity in frozencooked mussels was investigated. Ascorbic acid with and without chelating agents proved effective in arresting progression of oxidative rancidity, in samples held at – 12°C for 20 wk. However, these agents proved ineffective in preventing sensory deterioration of mussel meats under the same conditions. Mussels held at – 30°C showed an improved sensory stability throughout the study and demonstrated less progression of lipid oxidation compared with mussels held at – 12°C. Sensory deterioration at – 12°C storage is associated in part, with lipid oxidative changes. The ineffectiveness of antioxidant agents in preventing sensory deteriorative changes may indicate the presence of other, as yet undetermined, degradative pathways.     

The effect of salt concentration on rancidity in Gaziantep cheese

Gaziantep cheese is a non‐fermented and enzyme clotted type cheese. The changes in oxidative and hydrolytic rancidity in the cheese were analysed during its storage. Storage conditions were selected as 4, 10 and 20°C and 90, 170, 200 and 230 g kg⁻¹ salt solutions by considering the traditional storage conditions. Oxidative rancidity increased with increasing temperature and NaCl concentration in the brine. Hydrolytic rancidity increased with increasing temperature and decreasing salt content of the cheese. The extent of oxidative rancidity was found to be higher than hydrolytic rancidity. The results of this study showed that the storage temperature should not be higher than 10°C and brine concentration must be higher than 90 g kg⁻¹ and lower than 230 g kg⁻¹ to minimize lipid oxidation. Gaziantep cheese was organoleptically examined after 2 months of storage at 20°C and in 90, 170 and 230 g kg⁻¹ salt solutions, and it was found that even at a peroxide value around 1 meq kg⁻¹, acceptable levels of changes in flavour were observed. Sensory analysis results showed that textural properties of Gaziantep cheese changed with salt concentration of the brine. © 1999 Society of Chemical Industry     

Changes in Texture of Green Peas during Freezing and Frozen Storage

The effects of freezing (still-air, air-blast, and Freon immersion freezing) and frozen storage (?5°, ?10° and ?15°C for 0 to 48 wk) on texture of cooked frozen peas were examined. Peas frozen by a Freon-12 immersion method with no appreciable damage to cell structure had firmer and more chewy sensory textural quality compared to those peas frozen by a slower freezing method. Sensory tenderness decreased initially and then increased with storage time to the maximum storage times of 6 wk in ?5°C storage, 16 wk in ?10°C storage, and 48 wk in ?15°C storage. Sensory chewiness increased initially, then remained constant with storage time except in ?15°C storage. Generally, the lower storage temperature resulted in less sensory chewiness. The correlation coefficients (r) between sensory and objective measurements for tenderness and chewiness were 0.76 and 0.88 (P < 0.05), respectively.     

Protection of Menhaden Mince Lipids from Rancidity during Frozen Storage

Several antioxidants as well as vacuum packaging and changes in frozen storage temperatures (-7°C and -20°C) were tested for their effect on the peroxide values and free fatty acids (FFA) of frozen minces from Gulf menhaden, Brevoortia patronus and Atlantic men-haden, Brevoortia tyrannus. Vacuum packaging was the most effective in retarding oxidative rancidity. Storage at -20°C also reduced the oxidation versus -7°C. Ascorbic acid and crythorbic acid had the best antioxidant activity of the additives tested. Tocopherols, rosemary extracts, and tertiary butylhydroquinone (TBHQ) had limited antioxidant activity. Storage at -20°C inhibited hydrolytic rancidity. Neither vaccum packaging nor any of the additives prevented FFA development at -7°C.     

Inhibition of Oxidative Rancidity in Salted Ground Pork by Carnosine

Carnosine (0.5 and 1.5%) effectively inhibited formation of lipid peroxides and thiobarbituric acid reactive substances (TBARS) in frozen (? 15°C) salted ground pork during up to 6 mo storage. Inhibition of TBARS formation by carnosine (1.5%) was better than sodium tri-polyphosphate (0.5%), ot-tocopherol and butylated hydroxytoluene (0.02% of fat content). Carnosine was the most effective at preventing oxidative rancidity and color changes as determined by sensory panel, in salted ground pork after 1 mo frozen storage (?15°C). These data suggested that carnosine could be used as a “natural” antioxidant in muscle foods.     

Elevated concentrations of oxygen on the stability of live mussel stored refrigerated

The stability of bivalve molluscs was studied in live mussels (Mytilus galloprovincialis) packaged under modified atmospheres. Studies of physical, chemical, microbiological and sensory parameters have detailed these changes in the live packaged mussels. The highest survival was achieved at high oxygen concentrations, i.e. 75%, in the absence of carbon dioxide. The improved storage conditions promote shelf life in 80% of the packaged mussels, reaching a storage life of 6 days when held at 2–3 °C, whereas control molluscs packaged in air did not exceed 3–4 days when stored under the same conditions. Sensory analysis of cooked products from live mussels packaged under 75% oxygen:25% nitrogen were optimum throughout the period of storage. Secondly, the results for the most effective treatment were compared with those for an approximate 75–80% oxygen mixture achieved by applying partial vacuum to the packaging machine. This option employed only oxygen and decreased packaging time, which reduced mussel packaging stress by avoiding elevated vacuum conditions. It provided operational and economic advantage to commercial mussel packaging.     

The oxidative stability of lard at −20°C: Evidence for a synergistic prooxidant effect of copper and curing salts

In connection with an interest in the problem of rancidity development in cold-stored cured meat products (particularly bacon), the effect of certain trace components and permitted food additives on the oxidative stability of model systems containing lard was examined. Lard, to which additions of various single additives or combination of additives had been made, was stored for periods of up to 16 weeks at ?20°C. Samples were removed during this time to assess the extent of their oxidation by chemical analysis (peroxide value determination) and sensory evaluation (odour). The additives studied included water, sodium chloride, sodium nitrate, sodium nitrite and copper (as palmitate, acetate and sulphate). It was observed that there was progressive oxidative deterioration of the lard with noticeable rancidity developing after 8 to 16 weeks' storage at ?20°C when water, sodium chloride, sodium nitrate, sodium nitrite and copper were present in combination.     

Rancidity in Selected Sites of Frozen Catfish Fillets

Gas chromatographic volatiles and TBA values for three external fillet sites (lateral line, visceral-side and skin-side) and the fillet interior were compared with sensory evaluations of baked fillets to determine rancidity development. A sampling technique was developed that allowed procurement of the various fillet site tissues from whole fillets after storage at -20°C for up to 6 mo. The lateral line had the most rancidity while internal tissues had the least. Instrumental examination of the lateral line proved effective for predicting sensory detection of rancidity. Correlation coefficients for lateral line total volatiles and TBA values with flavor were 0.98 and 0.95, respectively.     

Color and Oxidative Rancidity of Gamma and Electron Beam-Irradiated Boneless Pork Chops

Color and oxidative rancidity were determined for chilled (3 ± 2°C) and frozen (?17 ± 3°C) boneless pork chops packaged in vacuum or air and irradiated to an absorbed dose of 0, 1.5 or 2.5 kGy (chilled) or 0, 2.5 or 3.85 kGy (frozen) of electron beam or cobalt⁶⁰ irradiation. Irradiation of vacuum-packaged chops produced redder, more stable (color and rancidity) product. More pronounced oxidative rancidity and less stable display color were noted for samples irradiated in aerobic packaging. Irradiation source had varying but limited effects on color and rancidity. Optimum packaging conditions can control color and rancidity changes in boneless chops, thereby enabling irradiation to be a useful intervention technology.     

Effect of Low Dose Irradiation of Pork Loins on the Microflora, Sensory Characteristics and Fat Stability

The effects of low dose (100 krad) irradiation on microflora, sensory characteristics, and development of oxidative rancidity of vacuum packaged pork loins was investigated after irradiation and during low temperature (4°C) storage up to 21 days. Irradiation reduced numbers of mesophiles, psychrotrophs, anaerobic bacteria (P<0.01), and staphylococci (P<0.05), with the effect on mesophiles and psychrotrophic spoilage organisms the greatest. Effect of irradiation on sensory characteristics of pork loin was minimal with no detectable differences between irradiated and nonirradiated pork after 14 days of storage. Irradiation of pork did not affect cooking loss or thiobarbituric acid values.     

Dried Pork as Influenced by Nitrate, Packaging Method and Storage

A new technique was developed to produce high quality, uniform and attractive thin sliced, cured dried pork. The effects of nitrate, packaging method and storage time on residual nitrite, TBA values, sensory properties and microbiological counts were determined. Residual nitrite decreased with increased storage time at 3 ± 1°C. The addition of nitrate plus vacuum packaging caused a greater residual nitrite level and a lower TBA value during storage. Nitrite and/or nitrate acted as an antioxidant to retard oxidative rancidity (TBA value). Dried pork manufactured by the technique described had no major rancidity problem and had an acceptable shelf life. Total aerobic plate counts, lactic acid producing microbial counts and total anaerobic counts were not affected by nitrate or packaging methods. Coliforms, molds and yeasts were not found in this dried pork.     

Natural Antioxidant Extract from Fenugreek (Trigonella foenumgraecum) for Ground Beef Patties

Ground beef patties (75% lean) containing synthetic antioxidants, or Fenugreek (Trigonella foenumgraecum) extracts were cooked to internal temperature 70°C, and evaluated for storage stability at 4°C. Thiobarbituric acid values of raw or cooked samples containing fenugreek extracts were lower than controls (P<0.05). Fenugreek extracts delayed the induction period of oxidative rancidity. No differences were observed in psychrotrophic bacterial counts, and samples containing fenugreek extracts had lower Hunterlab “a” and higher “b” values. Samples with Fenugreek extracts had better oxidative stability and Fenugreek may be a promising natural antioxidant source.     

Effect of Phosphate Blends on Stability of Cod Fillets in Frozen Storage

Atlantic cod fillets were dipped in commercial tripoly or metaphosphate solutions, frozen and stored at either –12 ° 0.5°C or –30°C (constant or with daily programmed fluctuations to ?26°C) for up to 26 wk. Phosphate treatments at both storage temperatures decreased thaw drip and cooked drip and yielded a product with higher raw and cooked moisture. Protein content of cooked drip from fillets stored at –12°C was reduced by phosphate treatment; no significant difference was found between treated and control samples at –30°C. Although salt extractable protein was lowered, phosphate treatment did not affect dimethylamine/formaldehyde formation. Sensory evaluation of treated fillets stored at –30°C (with daily fluctuation to –26°C) revealed phosphated fillets to be the most tender and, after 26 wk storage, the most highly acceptable. Tripolyphosphate treatment significantly retarded the increase of expressible fluid under abusive conditions of frozen storage.     

Color Stability and Microbial Growth Relationships in Beef as Affected by Endogenous α-Tocopherol

Longissimus muscle from Holstein steers supplemented with vitamin E at 500 or 2000 mg/head/day showed less surface metmyoglobin accumulation than controls during 12 days storage at 4°C. Temperature abuse at 25°C for 24 hr increased metmyoglobin formation; vitamin E supplementation diminished the adverse effect of temperature abuse. No differences (P > 0.05) in bacterial load were observed among the 3 vitamin E treatments during storage. Sensory panelists preferred vitamin E-supplemented beef steaks in visual acceptance. Panelist assessment of discoloration correlated highly with a value and hue angle. In general, elevated α-tocopherol concentrations in beef steaks did not affect panelist assessment of meat spoilage.     

Storage Stability of Intermediate Moisture Mullet Roe

A storage stability study was performed on intermediate moisture roe (a_w= 0.84, salt content = 4%). Samples were stored at various temperatures for up to 1 month. Microbial analyses indicated that bacteria could grow from 5–25°C. Fungi grew at 15° and 25°C while their growth was inhibited at 5°C; however, a lag phase was detected at 15°C. TBA values increased linearly during storage. Microbial analyses, chemical determination of rancidity and sensory evaluations showed that the product was still acceptable after 30 days storage at 5°, 15° or 25°C.     

Storage Life of Frozen Blocks of Patagonian Hake (Merluccius hubbsi) Filleted and Minced

Relevant parameters that reflect quality loss during frozen storage in filleted and minced Patagonian hake at two different temperatures were determined. Cooked sensory assessment, oxidative rancidity, dimethylamine, formaldehyde, salt soluble protein, free and expressive drip, refractive index, pH and total volatile bases, were evaluated over a lo-month period. Salt soluble protein decreased as formaldehyde and dimethylamine increased. Sensory evaluations and total volatile bases indicated that minced hake remains acceptable after 6 months at −20°C and 12 months at −30°C and fillets remain acceptable for over 12 months both at −20°C and −30°C.     

Quality changes and storage life of common carp (Cyprinus carpio) at various storage temperatures

The shelf life and freshness changes in pond-grown common carp (Cyprinus carpio L) during storage at 0–2°C, 5–6°C and room temperature (26–29°C) were investigated by sensory, microbiological, physical and chemical analyses. The effect of gutting on the shelf life during storage at 0–2°C was examined. Iodine/starch and potassium sorbate were examined for their effects on shelf life of whole fish stored at 0–2°C and 5–6°C. Sensory results indicated that the whole fish had a maximum shelf life of 24 to 25 days at 0– 2°C. The life of the fish to the point beyond which it would be unsuitable for sale (commercial shelf life) was 17 days at 0–2°C. Storage at 5–6°C shortened shelf life 2- to 2.5-fold. At room temperature (26–29°C), spoilage was evident after 13 h. Gutting the carp shortened its storage potential at 0–2°C. Iodine treatment of this species stored at 0–2°C and at 5–6°C did not extend shelf life. The maximum shelf life of sorbate-treated fish at 0–2°C and 5–6°C was extended by 1–2 days, commercial shelf life by 3–4 days. Total volatile basic nitrogen, pH and penetrometer analyses were not reliable indicators of changes in freshness during shelf life. Thiobarbituric acid values were not useful as rancid odours or flavours were not detected during storage.     

ENZYME ACTIVITY AND QUALITY OF FROZEN GREEN BEANS AS AFFECTED BY BLANCHING AND STORAGE

Effects of different blanching conditions on residual enzyme activities and quality changes in green beans during frozen storage were studied. Green beans were blanched at various temperature and time combinations at both pilot plant and commercial scales. After storage at —23°C for 3, 6, 9 and 12 months they were analyzed for residual activities of catalase, lipoxygenase, polyphenoloxidase and peroxidase; changes in sensory quality as evaluated by a taste panel; and color and firmness as measured with instruments. Most of enzymes were inactivated during normal blanching but the residual activities varied among enzymes. Beans blanched above 82°C for 3.5 min yielded higher sensory scores for the quality attributes tested than those blanched at the lower temperatures. However, there appears to be no direct relationship between the quality attributes measured and the residual enzyme activities during 12 months storage.     

Heat and storage effects on the flavour of peanuts

Two peanut varieties, Giza 4 and Giza 5 were subjected to different heat treatments such as drying in solar drier at air speed 0.5 and 2 m/sec with average temperature 45 and 60°C and heating in oven at 120 and 150°C. The sensory evaluation of the two varieties showed insignificant differences among varieties and heating processes. A correlation between the sensory and instrumental data was found. The high sensory scores of samples heated at 150°C were attributed to the presence of high concentration of pyrazines which were thought to contribute to flavour and aroma of fresh roasted peanut. A comparative study between the main chemical classes retained in peanut samples after storage for 3 months at room temperature showed that the aldehydes derived lipids increased significantly in the solar dried samples. The antioxidative components produced via Maillard reaction resulted in oxidative stability of the samples heated in oven     

Direct sampling gas-liquid chromatographic — mass spectrometric analysis of hexanal from non-nitrite and nitrite-cured bacon during storage

Direct sampling gas-liquid chromatography-mass spectrometry was used to quantitate hexanal levels in nitrite and non-nitrite cured loin bacon stored for two weeks at 4°C. The objective was to evaluate the effect of varying levels of sodium nitrite on the flavour of cured bacon. Non-nitrite cured bacon yielded greater amounts of hexanal than bacon cured with 40, 120 and 1000 ppm sodium nitrite. Initially the differences were not significant but became evident during storage. Hexanal produced by samples during storage paralleled subjective undesirable flavour estimates (r = ?0.88) and would undoubtedly be useful as an indicator of oxidative deterioration or rancidity for this product.