南瓜全粉生产工艺及设备

介绍了经过烘干，粉碎等工艺生产南瓜全粉的设备，工艺流程和操作要点，并制定了产品质量标准。     

Effect of selected antioxidants on the stability of dehydrated mashed potatoes

The antioxidants TBHQ, alpha-tocopherol, Prolong P (rosemary, thyme, marjoram mixture) or ascorbyl palmitate were not found able to replace the antioxidant BHA in potato flakes production if stored for up to 24 months. Ascorbyl palmitate gave good antioxidative protection up to 16 months of storage, and also protected against carotenoid degradation better than the other antioxidants. The ascorbyl palmitate lost its antioxidative effect after longer storage.     

Digestibility in vitro of dry mashed potato products

The in vitro digestibilities of potato granules and flakes were compared. The digestibility of flakes was superior to that of granules. By drum-drying mashed potatoes, as is customary in the manufacture of flakes, the digestibility was improved, whereas by repeatedly drying and wetting mashed potatoes, as in the manufacture of potato granules, digestibility was diminished. The dry matter content of mashed potatoes obtained by rehydrating potato granules was higher than that of rehydrated flakes. The influence of digestibility and dry matter content of rehydrated potato granules and flakes on digestion in humans is discussed.     

马铃薯熟泥添加量对挂面品质的影响

为简化马铃薯挂面生产工艺,研究利用马铃薯熟泥代替水制作马铃薯小麦挂面,添加马铃薯熟泥(水分含量81.11%)从65 g到85 g至200 g小麦粉中,探讨马铃薯熟泥添加量对挂面品质的影响。结果表明:随着混合面团中熟泥的增加,马铃薯面条的煮熟增重率和烹调损失率均呈上升趋势;L*值降低,a*值、b*值升高;马铃薯小麦挂面的断裂距离先升高后降低,断裂强度、坚实度和剪切功均呈下降趋势。     

Pleasantness in relation to difference threshold of NaCl in mashed potato

Difference threshold values for sodium chloride were determined to investigate to what extent just noticeable differences (jnd) affect preferences. Samples were unflavored, garlic-flavored and pepper-flavored mashed potato. At the reference concentration of 0.60% NaCl, the jnd value for unflavored and garlic-flavored samples was 0.07% NaCl, and for the pepper-flavored sample, 0.08% NaCl. The pleasantness of seven samples between ±9 jnds from the reference (0.60% NaCl), was rated on a graphic scale ranging from less pleasant to more pleasant (reference at the midpoint). Forty-one subjects participated in the test. For unflavored and garlic-flavored mashed potato, concentrations below 0.36% NaCl and above 0.82% NaCl, and for pepper-flavored, below 0.31% NaCl and above 0.83% NaCl, were required to obtain statistically significant differences in hedonic responses compared to the reference concentration.     

Rheological properties of mashed potatoes made from dehydrated flakes: effect of ingredients and freezing

 The rheological behaviour of mashed potatoes made from dehydrated potato flakes was studied using helical ribbon geometry, which enabled changes in the dynamic mechanical properties, as a function of ingredients concentration, to be followed. Mashed potatoes were also frozen in order to determine the changes that occurred in the cell structure. Response surface analysis was used to establish the empirical models for expressing the effects of significant ingredients on rheological properties. Results showed that both dynamic moduli (G′, and G") were significantly influenced by potato flake concentration (α<0.01) and the butter concentration (α<0.05 for G′ and a<0.10 for G″), while the salt concentration had a significant quadratic effect (α<0.05) on the storage modulus (G′). Significant interactions occurred between potato flakes and milk concentrations, and potato flakes and salt concentrations, and these were detected by the dynamic moduli. Breakdown of the cell wall by freezing decreased G′, G″ and η* values, showing that the frozen/thawed mashed potatoes consisted of dilute dispersions of swollen and disrupted intracellular starch granules. Received: 11 January 1999     

4D printing of mashed potato/purple sweet potato puree with spontaneous color change

In this study, the effects of pH (2.5, 6.5 and 7.8) and potato flake content (15%, 19%, 23% and 27%) on the properties of mashed potatoes (MP) were studied in terms of moisture distribution, rheological properties, texture properties and 3D printing performances. Results showed that the potato flake content was positively correlated with apparent viscosity, storage modulus (G′), and loss modulus (G″), while negatively correlated with tanδ and relaxation time (T₂). As the content of potato chips increased, the shape fidelity of MP increased after printing. The addition of citric acid increased MP's apparent viscosity, G′, hardness and gumminess, thus increasing its capacity to be self-supportable performance after deposition, while an opposite trend was observed when sodium bicarbonate was added. A dual-extrusion printer was furtherly used to manufacture a colorful 4D ready-to-eat food in terms of spontaneous color change by using anthocyanin-rich purple sweet potato puree and MP. Results indicated that the color change of MP was significantly correlated with the pH value and the potato flake content.Industrial relevanceThis work extends the conventional 3D printing of single material to multi-material, and potentially provides a new view on how to produce colorful food products by 4D printing in terms of spontaneous color change of 3D printed multi-material products.     

Sterilization of dehydrated potato granules with propylene oxide

Summary Results were provided for propylene oxide cold sterilization of dehydrated mashed potato granules that contained 7% moisture and 0.044% chloride. Treatment with an optimum concentration of 0.1% w/w sterilant for 6 days at 22° C gave a bacterial count reduction from 3.4 × 10⁵ to less than 5 × 10³, a low glycol residue of 29 ppm, and 12 ppm of chlorohydrin, with the 1-chloro-2-propanol isomer constituting 94% of the total. This indicated that, in spite of the granule pH of 5.62, nucleophilic attack in dehydrated granules involves nonprotonated propylene oxide. Based on NMR analysis, evidence was given that such sterilization does not result in detectable etherification of starch, even though its content of 83% on a dry basis places it as the major potentially reactive constituent.

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Sterilisation von getrocknetem Kartoffelpulver mit Propylenoxyd

Zusammenfassung Propylenoxyd wurde zur Kaltsterilisation von Kartoffelpulver mit 7% Feuchtigkeit und einen Chloridgehalt von 0,044% verwendet. Bei einem optimalen Gehalt des Sterilisationsmittels von 0,1% wurde die Behandlung während 6 Tagen bei 22° C durchgeführt, was eine Reduktion des Keimgehaltes von 3,4 × 10⁵ auf weniger als 5 × 10³ bewirkte. Der Glykolrückstand war mit 29 ppm niedrig, ebenfalls das Chlorohydrin mit 12 ppm, wobei das 1-Chlor-2-propanol 94% der beiden Isomere ausmachte. Dies ergab einen Hinweis, daß im Pulver trotz des pH-Wertes 5,62 nicht protoniertes Propylenoxyd als Acceptor nucleophiler Übergänge dient. Aufgrund von NMR-Untersuchungen wurde gefunden, daß die obengenannte Behandlung keine nachweisbare Ätherbildung der Stärke bewirkte, obwohl ihr Gehalt 83% des Trockengewichtes beträgt und damit als potentieller Hauptreaktionspartner anzusehen wäre.

     

Presence and significance of Bacillus cereus in dehydrated potato products

Dehydrated potato contains Bacillus cereus at a prevalences of 10 to 40% and at numbers usually less than 10(3) CFU g(-1). B. cereus in dehydrated potato is likely to be present as spores that are able to survive drying of the raw vegetable and may represent a significant inoculum in the reconstituted (rehydrated) product where conditions favor germination of, and outgrowth from, spores. Holding rehydrated mashed potato alone, or as part of another product (e.g., potato-topped pie), at temperatures above 10 degrees C and below 60 degrees C may allow growth of vegetative B. cereus. Levels exceeding 10(4) CFU g(-1) are considered hazardous to human health and may be reached within a few hours if stored inappropriately between these temperatures. Foods incorporating mashed potato prepared from dehydrated potato flakes have been implicated in B. cereus foodborne illness. This review is a summary of the information available concerning the prevalence and numbers of B. cereus in dehydrated potato flakes and the rate at which growth might occur in the rehydrated product.     

Comparison of the consistencies of cooked mashed potato prepared from seven varieties of potatoes

Potato protein concentrates (PPC) were isolated from potato juice of seven studied varieties by thermal coagulation of 6.0–6.2 pH juices at 90–95 °C, followed by freeze-drying. Three levels of PPC were added to cooked mashed potato to raise the protein contents to 3, 4 and 5%, along with three levels of dry potato to obtain similar dry matter contents in mashed potatoes after the additions. The consistency of cooked mashed potato was measured objectively by a “back extrusion cell” connected to an Instron 1140 texturometer. Studied varieties differed in their consistencies of cooked mashed potato which increased with the dry matter content and increased after applying additives: (PPC and dry cooked potato). In spite of the similar dry matter contents the hardness of cooked mashed potato was higher when the PPC was used as an additive than with the dry potato addition.     

重组牛肉生产牛肉干的研究

谷氨酰胺转胺酶是一种催化酰基转移反应的转移酶,它可使用酪蛋白、肌球蛋白、谷蛋白和乳球蛋白等分子之间产生交联,改变蛋白质的功能性质。采用碎牛肉为主要原料,配以各种辅料,添加谷氨酰胺转胺酶,经过多次试验,优化工艺配方,研制出一种色泽、口感、风味均被人们接受的重组牛肉干。      

Pectin lyase is a key enzyme in the maceration of potato tuber

The maceration of potato tuber (Solanum tuberosum cv Bintje) by technical enzyme preparations was examined with the aid of fluorescence microscopy using fluorescein diacetate as a dye. Treatment with Pectinex Ultra-SP-L from Aspergillus aculeatus resulted in a higher release of single viable cells and smaller clumps of cells than treatment with Rohament P from Aspergillus niger. Fractions with high pectin lyase and low polygalacturonase activity obtained by anion exchange chromatography of Pectinex Ultra SP-L showed the highest degree of maceration. When two different cloned polygalacturonases (PG1 and PG2) and a cloned pectin lyase (PL1) from A aculeatus were examined, the highest degree of maceration was observed with PL1. In conclusion, pectin lyase is probably the main enzyme in Pectinex Ultra-SP-L responsible for the maceration of potato tuber. © 1997 SCI.     

The influence of dehydrated potatoes processing on the glycoalkaloids content in coloured-fleshed potato

The aim of this study was to determine the effect of different temperatures of blanching and pre-drying used in the laboratory production of dried potato dice on the content of glycoalkaloids in red and blue fleshed potato varieties.     

脱水马铃薯粉对面包品质的影响

研究了不同添加量的脱水马铃薯粉对吐司方面包特性的影响,包括面包的松软度、弹性、体积以及产量等方面.结果表明,添加马铃薯粉对面包产量、柔软度以及体积具有比较明显的改善效果,但是对弹性效果不太明显;随着添加量的增加,各方面的改善效果程度减小,弹性指标甚至出现了减小.     

Some chemical and histological changes in dehydrated apple

The effects of several dehydration processes on chemical compounds which may contribute to apple flavours and histological changes were investigated. It was shown that the effects on chemical compounds and histological changes were minimal by freeze dehydration as compared with other dehydration processes studied. Cryogenic freezing and osmotic dehydration treatments prior to freeze dehydration prevented cellular damage during the freezing step and had little adverse effect on the tissue of freeze dehydrated apple slices.     

The effect of sample temperature on instrumental and sensory properties of mashed potato products

The effect of sample temperature on texture, firmness and the sensory attributes of fresh and frozen/thawed natural and commercial mashed potatoes was studied. Scanning electron microscopy was used to obtain information on the structure of potato cells and how this is affected by processing. Various parameters were measured and were found to increase at 55 °C, these changes could be related to gelatinisation of the starch remaining in the products. In natural mashed potato, texture profile analysis (TPA) and firmness parameters were lower in the processed than in the fresh samples, indicating a weakening of the structure; this was confirmed by photomicrographs. In commercial mashed potato, TPA parameters measured at 55 and 65 °C and firmness parameters measured at 25 °C were higher in the processed samples, indicating enhanced structural strength; this was confirmed by photomicrographs. Firmness per gram of product was the best instrumental parameter for measuring texture in these products. The results of the different analyses indicated that 55 °C was the preferred temperature for consumption of mashed potatoes.     

Quality changes during the storage of dehydrated chicken kebab mix

The level of binders (starch, refined wheat flour and milk powder) was optimised with respect to sensory quality of ready‐to‐eat kebab made from a dehydrated mix using the experiment based on the Box–Behnken design. The optimised levels (as % of cooked meat) were 4.5% starch, 9.5% refined wheat flour and 2% milk powder. Dehydrated chicken kebab mix prepared with optimised quantities of binders and spices was packed in metalised polyester pouches, stored at ambient temperature (27 ± 2 °C) for 6 months and sampled periodically for quality evaluation. A gradual decrease (P ≤ 0.05) in pH from 5.8 to 5.5, increases (P ≤ 0.05) in a_w from 0.31% to 0.42%, in moisture from 5.4% to 6.2%, in free fatty acid values from 0.99 to 1.74 as per cent oleic acid and in thiobarbituric acid numbers from 2.9 to 5.3 mg malonaldehyde kg^?1 were observed during storage. Hunter colour a values increased (P ≤ 0.05) from 0.30 to 1.29, whereas changes in Hunter L (51.8–53.4) and in Hunter b (19.0–19.5) values were marginal (P ≥ 0.05) during storage. The chicken kebab mix was microbiologically safe as indicated by low bacterial counts and absence of coliforms throughout the storage period of 6 months. Fried chicken kebabs prepared from mix stored for up to 6 months were acceptable.     

Rheological,thermal and sensory properties of whey protein concentrate/pectin‐fortified mashed potatoes made from dehydrated flakes

The effect of different amounts of whey protein concentrate (50–150 g kg^?1), low and high methoxyl pectin (5–15 g kg^?1) on the rheological, thermal, structural properties and sensory quality of mashed potatoes prepared from dried mashed potatoes flakes was investigated. The response surface technique was used to analyse the effects of whey protein concentrate and pectin simultaneously on the consistency index, flow behaviour index, apparent viscosity and Casson plastic viscosity. Both whey protein concentrate and pectin decreased the consistency of the mashed potatoes weakening its structure in all concentrations assayed. Results suggest that whey protein concentrate interacts with high methoxyl pectin through non‐covalent interactions. Based on the sensory evaluation results, up to 100 g kg^?1 whey protein concentrate with 15 g kg^?1 of low methoxyl pectin and 15 g kg^?1 of high methxyl pectin could be incorporated to dried mashed potatoes flakes without losing significantly the sensory quality of the product.     

Presence and growth of Bacillus cereus in dehydrated potato flakes and hot-held, ready-to-eat potato products purchased in New Zealand

Potato products prepared from dehydrated potato flakes have been implicated in foodborne illness incidents involving Bacillus cereus intoxications. B. cereus can survive as spores in potato flakes and can germinate and multiply in the rehydrated product. This study assessed the frequency and concentration of B. cereus in dehydrated potato flakes and hot-held, ready-to-eat mashed potato products. Of 50 packets of potato flakes tested, eight contained greater than 100 CFU/g B. cereus (maximum 370 CFU/g). The temperature of the potato portion of 44 hot-held food products was measured immediately after purchase, and 86% were below the safe hot-holding temperature of 60 degrees C. The potato portions were subsequently tested for B. cereus. Only two of the potato portions contained B. cereus at greater than 100 CFU/g, a potato-topped pastry (1000 CFU/g) and a container of potato and gravy (120 CFU/g). To assess multiplication of B. cereus in this food, we held rehydrated potato flakes with naturally occurring B. cereus at 37, 42, and 50 degrees C and tested them over 6 h. By 6 h, the number of B. cereus in potato stored at 37 degrees C had exceeded 10(3) CFU/g, was greater than 10(4) CFU/g at 50 degrees C, and was close to 10(6) CFU/g at 42 degrees C. Growth data were compared to predictions from the U.S. Department of Agriculture Pathogen Modeling Program (PMP 7.0). The PMP predictions were found to simulate the measured growth better at 42 degrees C than at 37 degrees C. Hot-held potato products should be safe for consumption if held at 60 degrees C or above or discarded within 2 h.