The Effect of Adding Thyme Extracts on Microbiological, Chemical and Sensory Characteristics of Yogurt

Abstract

This study evaluated the effects of adding alcoholic and aqueous extracts of thyme on microbiological, chemical and sensory characteristics of yogurt. Supplementation of yogurt with thyme extracts during storage time were found to influence on yogurt composition compared to plain yogurt. So, plain yogurt (PY), thyme alcoholic extract yogurt (TCEY) and thyme aqueous extract yogurt (TAEY) moisture content decreased in all yogurt treatments to reach 88.21%, 88.39% and 88.23%, respectively after 28 days of storage. Protein content increased after 28 days of storage and reached to 4.82%, 4.83% and 4.81%, respectively. Fat content tended to increase at the end of study period to reach 0.32%, 0.36 and 0.326% respectively. The ash percentage after 28 days of storage increased to reach 0.71%, 0.72% and 0.71%, respectively. Titratable acidity increased after 28 day to 1.28, 1.17 and 1.2 while the pH decreased to 4.24, 4.31 and 4.29 respectively. For sensory evaluation, (TCEY) was more acceptable followed by (TAEY) and (PY) respectively. Microbial content revealed that all yogurt treatments were close at zero time for lactic acid bacteria (LAB) content and increased gradually to (7.38, 7.31 and 7.32) log (cfu/ml) respectively, there wasn't any grow during all study periods in (TCEY) and (TAEY) for coliform and yeast & mold content, while there was a grow in (PY) after 14 day for coliform and after 21 day for yeast & mold.

Bioactivity, Physicochemical and Sensory Properties of Probiotic Yoghurt Made from Whole Milk Powder Reconstituted in Aqueous Fennel Extract

“…The present results revealed that using fennel extract in yoghurt milk did not influence significantly (p < 0.05) on the protein content of the manufactured yoghurt. Similar results were obtained by Caleja et al [4] and Al-Shawi et al [9], who reported that adding fennel or thyme extracts to yoghurt milk did not have an effect on the protein content compared to the control sample. The fat content of (PY), (FEY 2 ), (FEY 4 ) and (FEY 6 ) treatments was 3.14%, 3.18%, 3.20% and 3.24%, respectively (Table 1).…”

“…The sensory properties of yoghurt samples were assessed following the methods described by Nelson and Trout [26] and modified by Al-Shawi et al [9] by a team of 10 professional panelists from the Faculty of Agriculture, Zagazig University. The following scoring points were used for different properties: taste and flavor (45), textures (30), acidity (15) and general appearance (10).…”

“…In this respect, some additives have been used in food industry to improve the characteristics and properties of processed foods. These substances include nutritional and preservatives additives besides flavoring, coloring, and miscellaneous agents [1,[7][8][9]. However, several previous studies have indicated that excessive consumption of industrial food additives results in problems related to the respiratory system, nervous system and skin diseases, causing alarm about random and excessive use [8,10].…”

“…Furthermore, several natural extracts such as herbs and fruits, which have health-promoting properties such as antioxidant and antimicrobial effects, have been used as natural additives during yogurt manufacture to improve the functional and nutritional value of the final product [11,12]. An increased demand for natural antimicrobial substances as alternatives to replace the additives, and replacing additives with herbal extracts in food products, has attracted remarkable attention [9].…”

Ca and Mg Concentrations in Spices and Growth of Commonly Sporulated and Non-Sporulated Food-Borne Microorganisms According to Marketing Systems

“…In this sense, consumers are asking for less processed, safer and more stable foods, preferring to use natural ingredients [ 11 , 12 ], such as certain spices like cloves [ 3 ], especially to control the growth of non-sporulated anaerobic microorganisms such as Listeria monocytogenes , and of sporulated microorganisms such as Bacillus cereus and Clostridium perfringens . Other authors [ 13 ] have indicated that the addition of aqueous or alcoholic thyme extracts to yoghurt inhibited the development of moulds and yeasts.…”