Refined bleached deodorised palm oil (RBDPO) was blended with 4–25 wt‐% hydrogenated palm oil (HPO). The physical, chemical and rheological properties of these samples were studied during 4 wk of storage at 15 °C. During storage, it was observed that there was an increase in solid fat content, compression force, hardness index (HI), melting temperatures, and storage modulus (G') with increasing concentration of HPO in the blends and with storage time. X‐ray diffraction results showed that the crystal networks of the blends were stabilised in the β' polymorphic form. However, in pure RBDPO, a very weak β form was observed. An increase in storage modulus (G'), compression force and HI indicated that the crystal networks of the blends became more highly structured with increasing storage time and concentration of HPO, which implies that post‐hardening had occurred without transformation of the polymorphic form from β’ to β.
The palm stearin and palm kernel olein (PSPKOo) blend (at 31%) was incorporated into chitosan of different degree of deacetylation (DD) (85 and 95%) and molecular weight (MW) (100,000 and 300,000 Da) to form films, and the films were evaluated in terms of particle size, diameter and stability of emulsion, as well as thickness and tensile strength. The chitosan with 85% DD (MW 300,000 Da) and 31% PSPKOo blend resulted in the strongest film, while this chitosan varied with 15.5 and 31% of PSPKOo blends compared to physical properties of film. Emulsion blend containing 85% DD (MW 300,000 Da) and 31% PSPKOo blend of chitosan gave the biggest particle size, highest viscosity and the most stable emulsion, resulting in the thickest film with the highest tensile strength (TS) and elastic modulus (EM). The film was applied on cherry tomato and stored at 20C for 9 days. The chitosan film with 85% DD (MW 300,000 Da) and 31% PSPKOo blend was the most effective in reducing weight loss and maintaining firmness and redness of cherry tomato compared to the other two films. Hence, palm stearin (PS) showed potential to be used as a moisture barrier in fruit coating.
This study was carried out to evaluate the chemical changes in short-bodied mackerel during chilled (4 °C) and frozen (-18 °C) storage for 18 days. The chemical changes were monitored at three days interval using Peroxide Value (PV), Thiobarbituric Acid (TBA), Total Volatile Base Nitrogen (TVBN) and Trimethylamine (TMA) tests. The PV of both chilled and frozen mackerel significantly increased (p < 0.05) with storage time and the rate was significantly higher in chilled than frozen mackerel. Based on the results, the chilled and frozen mackerel started to become rancid at day 15 and day 18, respectively. Similar trend was observed for TBA value, where the malonaldehyde content significantly increased (p < 0.05) for both chilled and frozen mackerel with storage time, and the rate of increase was higher in chilled than frozen mackerel. The TVBN and TMA of chilled mackerel increased significantly during storage time, but the values declined in frozen mackerel which might be due to inhibitory effects of freezing on the bacterial activities and hence avoid accumulation of TMA. Based on the chemical analyses, chilled mackerel spoiled rapidly compared to frozen mackerel.Keywords: short-bodied mackerel, thiobarbituric acid, peroxide value, total volatile base nitrogen, trimethylamine Abstrak Kajian ini telah dijalankan untuk menilai perubahan kimia dalam tisu otot ikan kembung bertubuh pendek semasa penyimpanan pada suhu dingin (4 °C) dan suhu sejuk beku (-18 °C) selama 18 hari. Perubahan kimia telah dipantau selang tiga hari menggunakan ujian Nilai Peroksida (PV), Asid Tiobarbiturik (TBA), Jumlah Bes Nitrogen Meruap (TVBN) dan Trimetilamina (TMA). Nilai Peroksida ikan kembung pada kedua-dua suhu dingin dan sejuk beku meningkat dengan ketara (p < 0.05) semasa penyimpanan dan kadar peningkatan PV lebih ketara bagi ikan kembung yang disimpan pada suhu dingin berbanding suhu sejuk beku. Berdasarkan keputusan yang diperolehi, ikan kembung pada suhu dingin dan sejuk beku masing -masing menjadi tengik pada hari ke 15 dan ke 18 penyimpanan. Pola yang sama diperolehi bagi nilai TBA, di mana kandungan malonaldehid meningkat dengan ketara (p < 0.05) bagi kedua-dua ikan kembung pada suhu dingin dan suhu sejuk beku semasa penyimpanan, dan kadar kenaikan malonaldehid adalah lebih tinggi terhadap ikan kembung pada suhu dingin. Nilai TVBN dan TMA ikan kembung pada suhu dingin meningkat dengan ketara semasa penyimpanan. Walau bagaimanapun kedua-dua nilai ini menurun bagi ikan kembung sejuk beku disebabkan kesan perencatan sejuk beku terhadap aktiviti bakteria dan seterusnya mengelakkan pengumpulan TMA. Berdasarkan analisis kimia ini, ikan kembung dingin rosak lebih cepat berbanding dengan ikan kembung sejuk beku.Kata kunci: Ikan kembung bertubuh pendek, asid tiobarbiturik, nilai peroksida, jumlah bes nitrogen meruap, trimetilamina
The aim of this study was to determine the chemical changes in muscle tissue of shortfin scad during storage at chilled (4 °C) and frozen (-18 °C) conditions for 18 days. The chemical changes were monitored every three days for Thiobarbituric acid (TBA), Peroxide value (PV), Total Volatile Base Nitrogen (TVBN) and Trimethylamine (TMA) content. Results show that there was a significant difference (p<0.05) in peroxide and TBA values between chilled and frozen shortfin scad starting from day 3. The highest PV values occured in chilled and frozen shortfin scad at day 12 (1.57 mEq/kg and 1.13 mEq/kg, respectively), and then decreased due to decomposition of hydroperoxides to secondary products such as aldehydes, alcohols and ketones. In contrast, TBA reached the highest values at day 15 for both chilled and frozen shortfin scad. For TVBN content, only the chilled sample shows significant increased (p<0.05) with storage time. The TVBN values declined significantly (p<0.05) for frozen shortfin scad. The TMA values for both chilled and frozen shortfin scad increased during storage. However, the TMA values increased at a faster rate in chilled compared to frozen shortfin scad. Based on the PV, TBA, TVBN and TMA values, chilled shortfin scad undergoes spoilage at a faster rate compared to the frozen shortfin scad.Keywords: shortfin scad, thiobarbituric acid, peroxide value, total volatile base nitrogen, trimethylamine AbstrakMatlamat kajian ini adalah untuk menentukan perubahan kimia dalam tisu otot ikan selayang semasa penyimpanan pada suhu dingin (4 °C) dan sejuk beku (-18 °C) selama 18 hari. Perubahan kimia dipantau setiap tiga hari melalui ujian Asid Tiobarbiturik (TBA), Nilai Peroksida (PV), Jumlah Bes Nitrogen Meruap (TVBN) dan Trimetilamina (TMA). Hasil kajian menunjukkan terdapat perbezaan ketara (p<0.05) nilai peroksida dan nilai TBA antara ikan selayang yang disimpan pada suhu dingin dan sejuk beku bermula dari hari ketiga. Nilai PV tertinggi bagi ikan selayang berlaku pada hari ke 12 (masing-masing 1.57 mEq/kg dan 1.13 mEq/kg) bagi penyimpanan suhu dingin dan sejuk beku, dan kemudian menurun disebabkan penguraian hidroperoksida kepada produk sekunder seperti aldehid, alkohol dan keton. Sebaliknya, TBA mencapai nilai tertinggi pada hari ke 15 untuk ikan selayang yang disimpan pada kedua-dua suhu. Bagi nilai TVBN, hanya sampel dingin menunjukkan peningkatan ketara (p <0.05) bagi masa penyimpanan. Nilai TVBN menurun dengan ketara (p<0.05) bagi ikan selayang yang disejukbekukan. Nilai TMA untuk ikan selayang yang didingin dan disejukbeku meningkat semasa penyimpanan. Walau bagaimanapun, nilai TMA ikan selayang meningkat pada kadar yang lebih cepat dalam suhu dingin berbanding suhu sejuk beku. Berdasarkan nilai PV, TBA, TVBN dan TMA, ikan selayang yang disimpan pada suhu dingin mengalami kerosakan pada kadar yang lebih cepat berbanding dengan ikan selayang yang disimpan pada suhu sejuk beku.Kata kunci: ikan selayang, asid tiobarbiturik, nilai peroksida, jumlah bes nitrogen meruap dan trimetilamina
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