EFFECTS OF PROCESSING AND SQUALENE ON COMPOSITION AND OXIDATIVE STABILITY OF SEAL BLUBBER OIL

Effects of processing on constituents of seal blubber oil and that of squalene on oxidative stability of several oils were monitored. The content of α-tocopherol in oil decreased during processing, especially at the bleaching and deodorization steps. There was also a concurrent reduction in the contents of squalene and free fatty acids, especially during deodorization. Oils treated with squalene did not show any improved oxidative stability and in some cases were even less stable.     

EFFECT OF CHOCOLATE COATING ON OXIDATIVE STABILITY OF NORMAL AND HIGH OLEIC PEANUTS

Oxidative stability studies were performed on roasted high-oleic acid peanuts (HOP-SunOleic 95) and normal oleic acid peanuts (NOP-Florunner). Peanuts were dry-roasted to a Hunter Lab value of approximately 50. Chocolate-coated peanut bars (6"x4"×1/2") were prepared using milk chocolate, white chocolate, and reduced-fat chocolate (containing salatrim). Chocolate bars were stored at 25C and 0.60 water activity (a_w). Uncoated peanuts were stored at 0.60 and 0.19 a_w at 25C. Samples were removed from storage at 4-week intervals for peroxide value measurement. Oxidation of peanuts with chocolate coatings were higher than the peanuts that were stored uncoated at the same a_w. The peroxide values of NOP were similar for chocolate coated treatments and 0.60 a_w control but the 0.19 a_w control was 2–4 times higher than the others. Chocolate-coated peanuts had higher oxidation rates compared to uncoated peanuts.     

UNSAPONIFIABLE MATTER AND OXIDATIVE STABILITY OF COMMERCIALLY PRODUCED INDIAN RICE BRAN OILS

Chemically and physically refined rice bran oils (RBO) were investigated for their content and composition of unsaponifiable matter and oxidative stability. The chemically and physically refined rice bran oils contained 2.6 and 4.5% unsaponifiable matter, respectively. The content and composition of unsaponifiable matter for chemically and physically refined RBO were phytosterols, 0.96%and 1.40%; 4-methyl sterols, 0.51%and 1.12%; triterpene alcohols, 0.52% and 0.86%; and nonpolar components, 0.61% and 1.13%, respectively. The corresponding oxidative stability for the two oils were 2.80 h and 4.37 h, respectively. The content of unsaponifiable matter was influenced by residual amounts of wax and oryzanol in the refined oil as shown by the model experiments. Thus physical refining of rice bran oil requires a thorough dewaxing step to obtain a refined oil without haziness and with a lower amount of unsaponifiable matter.     

EFFECT OF PROCESSING ON SOME CHEMICAL CONSTITUENTS OF PISTACHIO NUTS

The effect of processing on changes in fatty acids, sugars and amino acids in pistaschio nuts during blanching, drying and roasting was monitored. Blanching in hot water led to some loss in fatty acids, sugars and amino acids. Roasting further decreased the availability of the constituents. The magnitude of loss of the constituents was in the following order: blanching > roasting > drying. The composition profile of each of the constituents was analyzed. There was variation in the distribution of fatty acids among the raw and processed nuts. Unsaturated fatty acids were more susceptible to changes during processing. The combined loss of oleic and linoleic acids amounted to 22.29% of that present in the raw nuts. Fructose, glucose, sucrose and raffinose were shown to be present in the nuts. The loss of sucrose was higher than the monosaccharides during processing. Glutamic acid, leucine, proline 56.50% of the amino acids present, and blanching, drying and roasting successively caused losses in the availability of these amino acids. The effect of processing on nutritional values has been a subject of concern to consumers and food processors. The present investigation reveals that the loss in various components in the nuts deserves more attention.     

EFFECT OF VARIOUS ANTIOXIDANTS ON THE OXIDATIVE STABILITY OF ACID AND ALKALI SOLUBILIZED MUSCLE PROTEIN ISOLATES

Protein isolates prepared from cod ( Gadus morhua ) myofibrillar proteins using acid or alkali solubilization are susceptible to oxidative rancidity. Oxidation could be delayed by the exogenous addition of antioxidants. The objective of this research was to compare the efficacy of antioxidants such as δ-tocopherol, butylated hydroxyanisole (BHA) and propyl gallate, to inhibit oxidation in acid- and alkali- solubilized cod protein isolates. Oxidation was catalyzed using cod hemolysate. Oxidation of lipids was monitored by the measurement of thiobarbituric acid reactive substances and painty odor. Results showed that protein isolates prepared using the acid process was significantly ( P <  0.05) more susceptible to lipid oxidation than alkali-solubilized protein isolates. Regardless of pH treatments, the efficacy of various antioxidants decreased in the order propyl gallate  >  BHA  >  δ-tocopherol.

PRACTICAL APPLICATIONS

Research has shown that seafood available for human consumption is rapidly getting depleted and that many fish species may become extinct in the next half-century or so. Acid and alkali solubilization methods are recent but well-known techniques used for preparing protein isolates from under-utilized aquatic species and the by-products of seafood industry. Although numerous researchers have studied the use of acid and alkali processes on several sources of seafood, almost no research has been done on the use of antioxidants to protect protein isolates from lipid oxidation. In our research, we have studied the effect of various antioxidants on the oxidative stability of acid- and alkali-solubilized fish myofibrillar proteins. The results from this work will enable the seafood industry to properly identify the process and the type of antioxidants required for making muscle food products with increased oxidative stability.     

THE EFFECT OF PROCESSING METHOD AND STORAGE TIME ON CONSTITUENTS OF TURKISH SAUSAGES (SUCUK)

Turkish sausages ( sucuk ) were produced by two methods (heat processing and traditional). Their moisture, pH and water activity and lipid stability were studied during refrigerated storage (4  ±  2C/90 days). Heat-processed (Therm) sausages had higher moisture content, water activity and pH values, and low thiobarbituric acid (TBA) values, free fatty acids (FFA) and peroxide values. FFA content of Therm sausages increased from 2.5 to 5.5% during storage and was significantly ( P <  0.05) affected by storage time. In the case of traditionally produced (Trad) sausages, there was no significant impact of storage time, but their TBA value increased from 0.38 to 0.48 mg MA/kg, while only a slight increase was observed in Therm sausages, from 0.41 to 0.43 mg MA/kg. Storage time significantly ( P <  0.05) increased the TBA value of Trad sausages.

PRACTICAL APPLICATIONS

In the current study, the effect of processing methods (heat processing and traditional) and storage time on some constituents of Turkish sausages was studied. Processing method significantly affected proximate composition of the sausages. On the other hand, lipolytic and oxidative changes were observed in both heat-processed and traditional sausages during storage. This could be attributed to hydrolytic enzymes and residual oxygen in vacuum packs. In practical applications, low oxygen permeability packing materials or modified gas atmosphere packing are recommended for both processing methods.     

SUPERIOR OXIDATIVE STABILITY OF DOCOSAHEXAENOIC ACID-ENRICHED OILS IN THE FORM OF PHOSPHOLIPIDS

Oxidative stabilities of docosahexaenoic acid (DHA, 22:6 n-3)-enriched oils (7.0 – 7.1 mol% of total fatty acids), in the form of phospholipids (PL), triacylglycerols (TG) and ethyl esters (EE), were comparatively investigated with those of control oil (palm oil supplemented with 20% soybean oil; containing no DHA). Autoxidation of sample oil (50 mg) was performed in a 10 mL glass vial at 25C for 42 days in the dark. During the oxidation, headspace oxygen absorption was significantly lower in oil in the form of PL than TG and EE, and was almost equivalent to that of control oil. At day 42 of oxidation, peroxide value and carbonyl value of PL were lower than those of TG and EE. The change of constituent fatty acids during the oxidation was larger in TG and EE than PL. The results indicated that DHA-enriched oils in the form of PL are more stable to autoxidation than those in the form of TG and EE.     

72—THE EFFECT OF PROCESSING OILS ON THE SHRINKAGE OF HERCOSETT-TREATED KNITTED WOOL FABRIC

An account is given of an investigation of the shrinkage on washing of knitted wool fabrics produced from chlorine–Hercosett-treated tops to which a range of additives had been applied. It is shown that the range of effects of the various additives is very wide and that about half of those tested had no effect on the shrinkage rate. Four increased the shrinkage rate by a factor of more than ten and thus would be clearly unsuitable for industrial use. Additives of all the types studied (mineral-oil-based, synthetic lubricants, and softeners) were capable of causing a marked increase in the shrinkage rate, but other additives of each general type had no significant effect, so that it was not possible to make a clear distinction on the basis of a general classification. It is suggested that one component, or group of components, in the additives had affected the Hercosett resin, but no firm conclusions could be drawn about the exact mechanisms.     

加工条件对芹菜汁和黄酮类化合物稳定性的影响

采用微波浸提芹菜中的黄酮类物质,微波功率450W,料水比1：4,浸提时间2min时,黄酮提取液为60.3%.果胶酶和PVPP结合处理条件为：果胶酶用量0.10%,PVPP使用量0.15%,处理4 h,芹菜汁澄清效果好,澄清汁中黄酮类物质的保留率高.处理后的芹菜汁在低pH值和高温作用下其透光率和黄酮保留率变化不大,可在高温和低pH值下处理.