New application of microbial l-glutaminase as a flavor enhancing agent in beef burgers

L‑glutaminase (L‑glutamine amidohydrolase EC3.5.1.2) is the key enzyme in enhancing the taste and aroma of oriental fermented foods by increasing their glutamic acid content and as a result imparting a palatable taste. Beef burgers were prepared using different levels of the partially purified L- glutaminase (2.0 to10.0 U/100 g) prepared from Aspergillus oryzae NRRL 32567. Beef burgers treated with 6.0 U/100g and the others treated with monosodium glutamate (5000 ppm) were chemically, sensory and microbiologically evaluated and compared to untreated control during frozen storage at –18 ºC for 3 months. Treatment with L‑glutaminase (6 U/100g) resulted in an increase of 443% in glutamic acid and a reduction of 63% in glutamine contents resulting in an enhanced preferable taste and odor of the prepared beef burgers. Burgers treated with 6.0 U/100g exhibited the best odor, texture, taste and overall quality scores when compared to the untreated control and samples treated with monosodium glutamate (5000 ppm). During the frozen storage of all samples, an expected slight, but significant (p≤0.05), increase in the total mesophilic bacterial count was evident and such increase was quite acceptable since numbers did not exceed the limit of 5.7x103 cfu/g. Similarly, the total psychrotrophs did not exceed 3.7x102 cfu/g.

Physicochemical and Microbiological Appearance of Sapera Goat's Milk on Frozen Storage

This study aims to examine the effect of the storage time of milk at a temperature of -18? on the chemical, physical and microbiological content due to different storage times. The goat's milk studied was the milk of the Sannen Crossbreed of the Sapera goat. Twenty samples were taken from the milking results on the same day. The design used in this study was a completely randomized design (CRD) with five treatments and four replications. Samples were grouped according to treatment, namely 0d (control) and 10d, 20d, 30d, 40d; stored for 10, 20, 30 and 40 days, respectively. The milk storage process is carried out using a freezer at a temperature of -18?. The physicochemical and microbiological parameters observed were protein, fat, lactose, solid-non-fat (SNF), total solid (TS), specific gravity, pH, total plate count (TPC), and coliform. Evaluation of milk quality is based on the Indonesian National Standard (SNI) and Thai Agricultural Standard (TAS). The results showed that storage time did not significantly affect the components of fat, protein, lactose, total plate count, and coliform (p> 0.05). In milk stored for 40 days, there were differences in the values of SNF, TS, specific gravity, and pH compared to control (p<0.05). In terms of chemical, physical and microbiological quality, Sapera goat's milk stored at -18? for 40 days still complies with SNI and TAS. The process of storing and freezing milk can be an alternative for preservation to ensure the physical and chemical quality of Sapera goat's milk.

Comparative Effect of Frying and Baking on Chemical, Physical, and Microbiological Characteristics of Frozen Fish Nuggets

The effects of deep-frying and oven-baking on chemical, physical, and microbiological, properties of cassava croaker (Pseudotolithus senegalensis) nuggets during frozen storage were investigated. The moisture, protein, fat, ash, and carbohydrate contents varied among the cooking methods and frozen storage times. The deep-fried nugget had a higher fat content, which resulted in a higher energy value (p < 0.05). The free fatty acid content and peroxide value (PV) of the oven-baked nuggets were higher than the deep-fried ones (p < 0.05). The PV tended to increase with increasing storage time, but it was still within the recommended range for consumption. The deep-fried nugget showed a vivid orange–yellow color, with higher L*, a*, and b* values, while oven-baked nuggets showed a pale-yellow color. The baked nuggets had relatively lower total expressible fluid than the deep-fried nuggets at all time points (p < 0.05). The hardness, springiness, and chewiness of deep-fried nuggets were higher than baked nuggets throughout the storage period (p < 0.05). The total plate count and yeast and mold counts produced by the two cooking methods were within the acceptable range throughout the storage.

Pengaruh Penyimpanan Beku terhadap Karakteristik Kimia dan Fisik Caulerpa racemosa, Drip, dan Filtratnya

Caulerpa racemosa merupakan rumput laut hijau dengan kandungan air yang tinggi sehingga mudah mengalami kerusakan. Penyimpanan dalam suhu beku merupakan salah satu cara untuk memperpanjang masa simpan suatu produk. Namun, pembekuan produk juga dapat menyebabkan terjadinya berbagai perubahan yang tidak dikehendaki. Penelitian ini bertujuan untuk menganalisis pengaruh penyimpanan pada suhu beku terhadap karakteristik kimia dan fisik C. racemosa, drip, dan filtrat yang dihasilkan. Sampel berupa C. rasemosa disimpan dalam ruangan penyimpan beku (cold storage) dan diamati setiap minggunya hingga minggu ke-4. Parameter uji yang diamati meliputi rendemen, komposisi proksimat, kadar garam, uji warna (L*, a*, b*), dan viskositas, masing-masing pada C. racemosa yang ditiriskan, drip, dan filtrat C. racemosa. Hasil penelitian menunjukkan bahwa penyimpanan beku C. racemosa dapat mengurangi berat pada sampel akhir karena sebagian besar drip keluar setelah pelelehan/thawing, yaitu sekitar 77,88-84,81%. Karakteristik fisik maupun kimia C. racemosa yang disimpan selama 1 hingga 4 minggu tidak berbeda nyata antar waktu penyimpanan, namun berbeda nyata pada C. racemosa tanpa disimpan beku, yaitu pada kadar air, abu, dan garam.ABSTRACTCaulerpa racemosa is a green seaweed that has a high moisture content, so it is easily damaged. Frozen storage is one way to extend the shelf life of a product. However, freezing the product can cause various undesirable changes to occur. This study was aimed to analyze the effect of storage at freezing temperature on the chemical and physical characteristics of C. racemosa, drip, and the resulting filtrate. C. racemosa samples were stored in cold storage and observed every week until the 4th week. The test parameters observed were yield, proximate composition, salt content, color (L*, a*, b*), and viscosity on drained C. racemosa, drip, and C. racemosa filtrate. The results showed that frozen storage of C. racemosa could cause weight loss in the final sample because most of the drip came out after thawing, which was around 77.88 - 84.81%. Physical and chemical characteristics of C. racemosa stored for 1 to 4 weeks were not significantly different from unfrozen C. racemosa, i.e. water, ash, and salt content.