EFFECT OF EVAPORATIVE COOLING STORAGE ON RIPENING AND QUALITY OF TOMATO

Tomatoes (Lycopersicon esculentum Mill cv. Rupali) ripened in evaporative cooling (EC) storage conditions (20°C–25°C, 92–95% RH) were compared with control fruits stored under room conditions (28°C–33°C, 45–65% RH) during summer in Mysore. EC ripened tomatoes on the 15th day reached 100% ripening index (RI) with a value of 2.48 for the ratio of redness to yellowishness (a/b) and hue angle (θ) of 22.1° whereas the control tomatoes on the same day reached a maximum 83.3% RI with a/b ratio of 1.59 and a hue angle of 32.9°. Higher development of chroma and total color difference were exhibited by EC stored tomatoes than control samples. The lycopene content of EC ripened fruits double that of the control. EC stored fruits showed lower values for rupture and shear stresses. The rate of moisture loss for control fruits was 6.5 times as great as for EC stored tomatoes.     

EFFECT OF TEMPERATURE ON THE QUALITY OF MUSCLE FOODS

Heating/cooking alters a food's flavor precursors yielding a product with a new pleasing taste. While heating to a high temperature destroys most pathogens thereby enhancing safety, it also alters the food's flavor by changing the precursors and final flavor components of the food. For example, heating meat to above 77C not only destroys many foodborne pathogens but also causes major changes in level of desirable flavor precursors. Many of these changes are due to alteration in activity of endogenous hydrolytic enzymes as well as heatinduced structural and functional changes. Heating induces differential production and distribution of flavor principles and flavor precursors. A secondary effect of temperature on food-flavor is its direct affect on analysis of flavor volatiles, i.e., high purge temperatures bias analysis of flavor components by production of new and destruction of existing components. This paper focuses on the structure/function relationship of meat proteins and their proteolytic products as they relate to meat flavor and end-point cooking temperature. The paper also will address the effect of analytical temperature on meat flavor analysis.     

低温贮存对刺儿菜品质的影响

研究了剌儿菜在0～4℃的低温贮存条件下，不同贮存时间对其氨基态氮、总酸性物质、可溶性糖、Vc、硝酸盐、亚硝酸盐含量的影响。结果表明：刺儿菜中总酸性物质含量在贮存的第1d下降很快，贮存的1～3天没有明显变化，贮存3d以后有缓慢增加的趋势。可溶性糖含量在贮存的第1天达到高峰，以后逐渐下降。维生素C含量随贮存天数的增加而降低；氨基态氮和硝酸盐含量随贮存天数的增加而增加；亚硝酸盐含量在贮存的第1d时达高峰，贮存到第3d时达到低峰，以后又逐渐增加。     

EFFECT OF ULTIMATE pH ON THE QUALITY CHARACTERISTICS OF PORK

A study was conducted to characterize the relationship between Longissimus thoracis ultimate pH(LTpH) and pork quality. Animals (n = 47) were selected based on LTpH measured at 24 h postmortem. Data were analyzed using regression procedures with ultimate pH as the independent variable, and relationships were determined to be linear (L), quadratic (Ql or cubic (C). Ultimate pH explained 79% (C) of the variation in subjective color, which increased as pH increased. Drip loss, purge loss and L* value decreased as LTpH increased (R²= 0.57C, 0.77 Q and 0.68 Q, respectively). Shear force decreased and sensory juiciness increased as LTpH increased (R²= 0.26Q and 0.46C, respectively). However, of flavor intensity increased as LTpH fell below pH 5.2 or exceeded 6.1(R²=0.52C). Increasing LTpH, up to a point, will improve fresh pork quality and processed meat properties, whereas, above approximately 6.1, of-flavor may increase.     

不同加热温度和时间对食用调和油品质的影响

研究了在130℃、150℃和170℃下,加热0～12h对食用调和油的酸价（AV）、过氧化值（POV）及丙二醛（MAD）含量的影响.结果表明：食用调和油的AV、POV随加热温度和时间的增加而增加,MAD含量随加热温度的增加而增加,随时间的延长开始增加,达到一最大值后又下降.     

CHANGES IN FLAVOR ATTRIBUTES DURING RIPENING OF FERMENTED SAUSAGES

Production of flavor-related compounds (amines and short-chain fatty acids) was followed throughout the ripening of a fermented sausage, and related to populations of two spoilage microorganisms (pseudomonds and Brochothrix thermosphacta) and lactic acid bacteria (LAB). Changes in pH, acidity, degree of oxidation and water activity were observed. Although spoilage microorganisms were present through ripening to 30 days, no off-odor was detected. The antibacterial activity of LAB, including Lactobacillus plantarum, was caused by a lower pH, as well as lactic acid, bacteriophage, and bacteriocin-like compounds synthesized by the strain. The concentration of short-chain fatty acids, mainly acetic acid, increased toward the end of the study time as a consequence of microbial metabolism. Putrescine and cadaverine, produced by Bacillaceae, increased during the first six days of storage, remaining constant through 30 days of ripening. Tyramine, a metabolic product of lactic acid baceria decreased after 24 days of storage.     

EFFECT OF CARRAGEENAN ON PROCESSING AND QUALITY CHARACTERISTICS OF LOW-FAT FRANKFURTERS

Three types of carrageenan (K, I, K+I) × 4 levels (0, 0.25, 0.5 and 1.0%) were evaluated with a complete factorial design to characterize the effect of carrageenans on processing and quality characteristics of low-fat frankfurters (9% fat, 13% protein). l-Carrageenan at 0.5–1.0% level appeared to be more beneficial for the production of low-fat frankfurters. It reduced (P<0.05) the hardness of the skin and contributed to a softer (P<0.05) product and higher overall acceptability. Low-fat frankfurters (9% fat) manufactured with I-carrageenan (IC) or in combination with finely ground toasted bread (TB), isolated soy protein (ISP) and pork skin (PSK), were compared to high-fat (27% fat, 11% protein) and to low-fat (9% fat, 13% protein) control frankfurters prepared with 3.5% potato starch (PS), as well as with commercial frankfurters (25% fat, 11.6% protein, 4.5% starch). Frankfurters with IC had higher (P<0.05) moisture, softer (P<0.05) skin and the highest (P<0.05) separation of gelatin. However, textural properties and overall acceptability were similar (P>0.05) to commercial and high-fat control frankfurters. Addition of TB had no significant effect. Use of ISP and PSK improved (P<0.05) the water-binding capacity but negatively affected the overall acceptability of frankfurters.     

不同种类的糖对中式香肠发酵的影响

葡萄糖、蔗糖、乳糖和麦芽糖对中式香肠发酵的影响进行了研究.结果表明,糖的添加有助于降低制品的pH值、增加乳酸量、减少亚硝酸盐残留量、促进良好风味的形成.37℃发酵36 h后,其pH值、乳酸量和亚硝酸盐残留量均与对照组有显著差异（P＜0.05）.发酵速率以葡萄糖组和蔗糖组较快,但这两者之间无显著差异（P＞0.05）.不同蔗糖添加量（1,2,4%）时,经36 h发酵,其PH值和乳酸量无明显差异（P＞0.05）.蔗糖用量为6%～8%时制品风味最佳.     

STUDIES ON THE EFFECT OF TEMPERATURE ON THE MOISTURE SORPTION CHARACTERISTICS OF POTATOES

An understanding of the moisture sorption characteristics of food systems is an important objective in food engineering, in particular with respect to the mass transport phenomena during drying. A standard gravimetric technique was employed to examine the influence of temperature on the adsorption and desorption behavior for potatoes. The type II sorption isotherms were analysed using the Guggenheim-Anderson-de Boer model, with the observed hysteresis phenomena displaying a temperature dependence. The moisture dependent net isosteric heats of sorption were determined using the Clausius-Clapeyron equation.     

EFFECT OF TEMPERATURE AND WATER CONCENTRATION DURING PROCESSING ON FOOD QUALITY

Water content and temperature during food processing have a pronounced influence on the rates of those changes in food properties which are the object of the process such as reduction in water content or sterilization. However, they also strongly influence adverse side effects such as browning, loss of nutrients or shrinking. When the effects of temperature and water concentration on the process rates of the desired and adverse processes are known, the processes can be optimized. An example of the optimization procedure is given for the spray drying of heat-labile aroma containing liquid foods. Both temperature and moisture content of the droplets change with time in spray-drying. In a second example a new and simple calculation method is introduced for the optimization of quality retention in the sterilization of packed foods.     

EFFECT OF ADDITIVES ON RHEOLOGICAL CHARACTERISTICS AND QUALITY OF WHEAT FLOUR PAROTTA

Effects of oxidizing agents (potassium bromate [20 and 40 ppm], ascorbic acid [100 and 200 ppm] and potassium iodate [20 and 40 ppm]), reducing agents (potassium metabisulphite [100 and 200 ppm] and cysteine hydrochloride [50 and 100 ppm]), enzymes (fungalα‐amylase [10 and 20 ppm] and protease [10 and 20 ppm]) and dry gluten powder (1, 2 and 3%) on rheological characteristics of dough and quality of parotta were studied. Addition of oxidizing agents and dry glutenincreased values for farinograph stability, extensograph and mixograph areas, apparent biaxial extensional viscosity, compressive stress, hardness and cohesiveness, while reducing agents and enzymes decreased the aforementioned characteristics and increased force decay parameter and adhesiveness of the dough. Among the different additives studied, incorporation of 100‐ppm potassium metabisulphite, 50‐ppm cysteine hydrochloride and 10‐ppm protease increased the overall quality score of parotta.     

EFFECT OF FISH PROTEIN PREPARATIONS ON RHEOLOGICAL PROPERTIES OF MEAT SAUSAGES

The properties of sausage emulsions, containing up to 30% fish proteins in respect to total N × 6.25, were characterized by viscosity and water holding capacity and after heating by yield, quantity of expressible fluid, water holding capacity, yield limit, creep curve, and sensory quality. Substitution of 15% meat protein by fish protein does not decrease the sausage yield nor impair the rheological properties of the formulation or of the cooked product. Sensory differences were detectable between the controls and sausages containing up to 10% of fish isolate or 20% concentrate.     

EFFECT OF CHEMICAL INHIBITORS AND STORAGE TEMPERATURE ON THE QUALITY OF FRESH-CUT POTATOES1

Fresh‐cut potato strips were dipped in 1% N‐acetyl‐L‐cysteine (NALC), 1% diethylenetriamine pentaacetic acid (DTPA) and 5% erythorbic acid ‐ 1% citric acid (EACA) prior to storage under modified atmosphere at 1 and 6C. Color changes over a 21 day storage period were assessed by tristimulus colorimetry; microbial changes (total aerobic populations, lactic acid bacteria, yeast and mold) by standard microbiological methods; and color, texture, exudation, off odor and integrated quality assessment by a six‐member sensory panel. All chemical treatments delayed color changes, microbial growth and sensory alterations in the stored potatoes. However, dipping in EACA was the only treatment that yielded product that compared favorably with freshly prepared potatoes after 14 days at 1C or 7 days at 6C. The effectiveness of all the treatments was strongly affected by storage temperature.